forked from Minki/linux
e202d55b05
756 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Tejun Heo
|
703c270887 |
writeback: implement and use inode_congested()
In several places, bdi_congested() and its wrappers are used to
determine whether more IOs should be issued. With cgroup writeback
support, this question can't be answered solely based on the bdi
(backing_dev_info). It's dependent on whether the filesystem and bdi
support cgroup writeback and the blkcg the inode is associated with.
This patch implements inode_congested() and its wrappers which take
@inode and determines the congestion state considering cgroup
writeback. The new functions replace bdi_*congested() calls in places
where the query is about specific inode and task.
There are several filesystem users which also fit this criteria but
they should be updated when each filesystem implements cgroup
writeback support.
v2: Now that a given inode is associated with only one wb, congestion
state can be determined independent from the asking task. Drop
@task. Spotted by Vivek. Also, converted to take @inode instead
of @mapping and renamed to inode_congested().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Greg Thelen
|
c4843a7593 |
memcg: add per cgroup dirty page accounting
When modifying PG_Dirty on cached file pages, update the new
MEM_CGROUP_STAT_DIRTY counter. This is done in the same places where
global NR_FILE_DIRTY is managed. The new memcg stat is visible in the
per memcg memory.stat cgroupfs file. The most recent past attempt at
this was http://thread.gmane.org/gmane.linux.kernel.cgroups/8632
The new accounting supports future efforts to add per cgroup dirty
page throttling and writeback. It also helps an administrator break
down a container's memory usage and provides evidence to understand
memcg oom kills (the new dirty count is included in memcg oom kill
messages).
The ability to move page accounting between memcg
(memory.move_charge_at_immigrate) makes this accounting more
complicated than the global counter. The existing
mem_cgroup_{begin,end}_page_stat() lock is used to serialize move
accounting with stat updates.
Typical update operation:
memcg = mem_cgroup_begin_page_stat(page)
if (TestSetPageDirty()) {
[...]
mem_cgroup_update_page_stat(memcg)
}
mem_cgroup_end_page_stat(memcg)
Summary of mem_cgroup_end_page_stat() overhead:
- Without CONFIG_MEMCG it's a no-op
- With CONFIG_MEMCG and no inter memcg task movement, it's just
rcu_read_lock()
- With CONFIG_MEMCG and inter memcg task movement, it's
rcu_read_lock() + spin_lock_irqsave()
A memcg parameter is added to several routines because their callers
now grab mem_cgroup_begin_page_stat() which returns the memcg later
needed by for mem_cgroup_update_page_stat().
Because mem_cgroup_begin_page_stat() may disable interrupts, some
adjustments are needed:
- move __mark_inode_dirty() from __set_page_dirty() to its caller.
__mark_inode_dirty() locking does not want interrupts disabled.
- use spin_lock_irqsave(tree_lock) rather than spin_lock_irq() in
__delete_from_page_cache(), replace_page_cache_page(),
invalidate_complete_page2(), and __remove_mapping().
text data bss dec hex filename
8925147 1774832 1785856 12485835 be84cb vmlinux-!CONFIG_MEMCG-before
8925339 1774832 1785856 12486027 be858b vmlinux-!CONFIG_MEMCG-after
+192 text bytes
8965977 1784992 1785856 12536825 bf4bf9 vmlinux-CONFIG_MEMCG-before
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Linus Torvalds
|
818099574b |
Merge branch 'akpm' (patches from Andrew)
Merge third set of updates from Andrew Morton:
- the rest of MM
[ This includes getting rid of the numa hinting bits, in favor of
just generic protnone logic. Yay. - Linus ]
- core kernel
- procfs
- some of lib/ (lots of lib/ material this time)
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (104 commits)
lib/lcm.c: replace include
lib/percpu_ida.c: remove redundant includes
lib/strncpy_from_user.c: replace module.h include
lib/stmp_device.c: replace module.h include
lib/sort.c: move include inside #if 0
lib/show_mem.c: remove redundant include
lib/radix-tree.c: change to simpler include
lib/plist.c: remove redundant include
lib/nlattr.c: remove redundant include
lib/kobject_uevent.c: remove redundant include
lib/llist.c: remove redundant include
lib/md5.c: simplify include
lib/list_sort.c: rearrange includes
lib/genalloc.c: remove redundant include
lib/idr.c: remove redundant include
lib/halfmd4.c: simplify includes
lib/dynamic_queue_limits.c: simplify includes
lib/sort.c: use simpler includes
lib/interval_tree.c: simplify includes
hexdump: make it return number of bytes placed in buffer
...
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Vladimir Davydov
|
cb731d6c62 |
vmscan: per memory cgroup slab shrinkers
This patch adds SHRINKER_MEMCG_AWARE flag. If a shrinker has this flag set, it will be called per memory cgroup. The memory cgroup to scan objects from is passed in shrink_control->memcg. If the memory cgroup is NULL, a memcg aware shrinker is supposed to scan objects from the global list. Unaware shrinkers are only called on global pressure with memcg=NULL. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Greg Thelen <gthelen@google.com> Cc: Glauber Costa <glommer@gmail.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
|
6bec003528 |
Merge branch 'for-3.20/bdi' of git://git.kernel.dk/linux-block
Pull backing device changes from Jens Axboe: "This contains a cleanup of how the backing device is handled, in preparation for a rework of the life time rules. In this part, the most important change is to split the unrelated nommu mmap flags from it, but also removing a backing_dev_info pointer from the address_space (and inode), and a cleanup of other various minor bits. Christoph did all the work here, I just fixed an oops with pages that have a swap backing. Arnd fixed a missing export, and Oleg killed the lustre backing_dev_info from staging. Last patch was from Al, unexporting parts that are now no longer needed outside" * 'for-3.20/bdi' of git://git.kernel.dk/linux-block: Make super_blocks and sb_lock static mtd: export new mtd_mmap_capabilities fs: make inode_to_bdi() handle NULL inode staging/lustre/llite: get rid of backing_dev_info fs: remove default_backing_dev_info fs: don't reassign dirty inodes to default_backing_dev_info nfs: don't call bdi_unregister ceph: remove call to bdi_unregister fs: remove mapping->backing_dev_info fs: export inode_to_bdi and use it in favor of mapping->backing_dev_info nilfs2: set up s_bdi like the generic mount_bdev code block_dev: get bdev inode bdi directly from the block device block_dev: only write bdev inode on close fs: introduce f_op->mmap_capabilities for nommu mmap support fs: kill BDI_CAP_SWAP_BACKED fs: deduplicate noop_backing_dev_info |
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Johannes Weiner
|
241994ed86 |
mm: memcontrol: default hierarchy interface for memory
Introduce the basic control files to account, partition, and limit
memory using cgroups in default hierarchy mode.
This interface versioning allows us to address fundamental design
issues in the existing memory cgroup interface, further explained
below. The old interface will be maintained indefinitely, but a
clearer model and improved workload performance should encourage
existing users to switch over to the new one eventually.
The control files are thus:
- memory.current shows the current consumption of the cgroup and its
descendants, in bytes.
- memory.low configures the lower end of the cgroup's expected
memory consumption range. The kernel considers memory below that
boundary to be a reserve - the minimum that the workload needs in
order to make forward progress - and generally avoids reclaiming
it, unless there is an imminent risk of entering an OOM situation.
- memory.high configures the upper end of the cgroup's expected
memory consumption range. A cgroup whose consumption grows beyond
this threshold is forced into direct reclaim, to work off the
excess and to throttle new allocations heavily, but is generally
allowed to continue and the OOM killer is not invoked.
- memory.max configures the hard maximum amount of memory that the
cgroup is allowed to consume before the OOM killer is invoked.
- memory.events shows event counters that indicate how often the
cgroup was reclaimed while below memory.low, how often it was
forced to reclaim excess beyond memory.high, how often it hit
memory.max, and how often it entered OOM due to memory.max. This
allows users to identify configuration problems when observing a
degradation in workload performance. An overcommitted system will
have an increased rate of low boundary breaches, whereas increased
rates of high limit breaches, maximum hits, or even OOM situations
will indicate internally overcommitted cgroups.
For existing users of memory cgroups, the following deviations from
the current interface are worth pointing out and explaining:
- The original lower boundary, the soft limit, is defined as a limit
that is per default unset. As a result, the set of cgroups that
global reclaim prefers is opt-in, rather than opt-out. The costs
for optimizing these mostly negative lookups are so high that the
implementation, despite its enormous size, does not even provide
the basic desirable behavior. First off, the soft limit has no
hierarchical meaning. All configured groups are organized in a
global rbtree and treated like equal peers, regardless where they
are located in the hierarchy. This makes subtree delegation
impossible. Second, the soft limit reclaim pass is so aggressive
that it not just introduces high allocation latencies into the
system, but also impacts system performance due to overreclaim, to
the point where the feature becomes self-defeating.
The memory.low boundary on the other hand is a top-down allocated
reserve. A cgroup enjoys reclaim protection when it and all its
ancestors are below their low boundaries, which makes delegation
of subtrees possible. Secondly, new cgroups have no reserve per
default and in the common case most cgroups are eligible for the
preferred reclaim pass. This allows the new low boundary to be
efficiently implemented with just a minor addition to the generic
reclaim code, without the need for out-of-band data structures and
reclaim passes. Because the generic reclaim code considers all
cgroups except for the ones running low in the preferred first
reclaim pass, overreclaim of individual groups is eliminated as
well, resulting in much better overall workload performance.
- The original high boundary, the hard limit, is defined as a strict
limit that can not budge, even if the OOM killer has to be called.
But this generally goes against the goal of making the most out of
the available memory. The memory consumption of workloads varies
during runtime, and that requires users to overcommit. But doing
that with a strict upper limit requires either a fairly accurate
prediction of the working set size or adding slack to the limit.
Since working set size estimation is hard and error prone, and
getting it wrong results in OOM kills, most users tend to err on
the side of a looser limit and end up wasting precious resources.
The memory.high boundary on the other hand can be set much more
conservatively. When hit, it throttles allocations by forcing
them into direct reclaim to work off the excess, but it never
invokes the OOM killer. As a result, a high boundary that is
chosen too aggressively will not terminate the processes, but
instead it will lead to gradual performance degradation. The user
can monitor this and make corrections until the minimal memory
footprint that still gives acceptable performance is found.
In extreme cases, with many concurrent allocations and a complete
breakdown of reclaim progress within the group, the high boundary
can be exceeded. But even then it's mostly better to satisfy the
allocation from the slack available in other groups or the rest of
the system than killing the group. Otherwise, memory.max is there
to limit this type of spillover and ultimately contain buggy or
even malicious applications.
- The original control file names are unwieldy and inconsistent in
many different ways. For example, the upper boundary hit count is
exported in the memory.failcnt file, but an OOM event count has to
be manually counted by listening to memory.oom_control events, and
lower boundary / soft limit events have to be counted by first
setting a threshold for that value and then counting those events.
Also, usage and limit files encode their units in the filename.
That makes the filenames very long, even though this is not
information that a user needs to be reminded of every time they
type out those names.
To address these naming issues, as well as to signal clearly that
the new interface carries a new configuration model, the naming
conventions in it necessarily differ from the old interface.
- The original limit files indicate the state of an unset limit with
a very high number, and a configured limit can be unset by echoing
-1 into those files. But that very high number is implementation
and architecture dependent and not very descriptive. And while -1
can be understood as an underflow into the highest possible value,
-2 or -10M etc. do not work, so it's not inconsistent.
memory.low, memory.high, and memory.max will use the string
"infinity" to indicate and set the highest possible value.
[akpm@linux-foundation.org: use seq_puts() for basic strings]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Vladimir Davydov
|
90cbc25088 |
vmscan: force scan offline memory cgroups
Since commit
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Vlastimil Babka
|
cfc5115579 |
mm, vmscan: wake up all pfmemalloc-throttled processes at once
Kswapd in balance_pgdate() currently uses wake_up() on processes waiting in throttle_direct_reclaim(), which only wakes up a single process. This might leave processes waiting for longer than necessary, until the check is reached in the next loop iteration. Processes might also be left waiting if zone was fully balanced in single iteration. Note that the comment in balance_pgdat() also says "Wake them", so waking up a single process does not seem intentional. Thus, replace wake_up() with wake_up_all(). Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michael S. Tsirkin
|
17636faada |
mm/vmscan: fix highidx argument type
for_each_zone_zonelist_nodemask wants an enum zone_type argument, but is passed gfp_t: mm/vmscan.c:2658:9: expected int enum zone_type [signed] highest_zoneidx mm/vmscan.c:2658:9: got restricted gfp_t [usertype] gfp_mask mm/vmscan.c:2658:9: warning: incorrect type in argument 2 (different base types) mm/vmscan.c:2658:9: expected int enum zone_type [signed] highest_zoneidx mm/vmscan.c:2658:9: got restricted gfp_t [usertype] gfp_mask convert argument to the correct type. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Rik van Riel <riel@redhat.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Suleiman Souhlal <suleiman@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Christoph Hellwig
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de1414a654 |
fs: export inode_to_bdi and use it in favor of mapping->backing_dev_info
Now that we got rid of the bdi abuse on character devices we can always use sb->s_bdi to get at the backing_dev_info for a file, except for the block device special case. Export inode_to_bdi and replace uses of mapping->backing_dev_info with it to prepare for the removal of mapping->backing_dev_info. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com> |
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Vlastimil Babka
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9e5e366172 |
mm, vmscan: prevent kswapd livelock due to pfmemalloc-throttled process being killed
Charles Shirron and Paul Cassella from Cray Inc have reported kswapd
stuck in a busy loop with nothing left to balance, but
kswapd_try_to_sleep() failing to sleep. Their analysis found the cause
to be a combination of several factors:
1. A process is waiting in throttle_direct_reclaim() on pgdat->pfmemalloc_wait
2. The process has been killed (by OOM in this case), but has not yet been
scheduled to remove itself from the waitqueue and die.
3. kswapd checks for throttled processes in prepare_kswapd_sleep():
if (waitqueue_active(&pgdat->pfmemalloc_wait)) {
wake_up(&pgdat->pfmemalloc_wait);
return false; // kswapd will not go to sleep
}
However, for a process that was already killed, wake_up() does not remove
the process from the waitqueue, since try_to_wake_up() checks its state
first and returns false when the process is no longer waiting.
4. kswapd is running on the same CPU as the only CPU that the process is
allowed to run on (through cpus_allowed, or possibly single-cpu system).
5. CONFIG_PREEMPT_NONE=y kernel is used. If there's nothing to balance, kswapd
encounters no voluntary preemption points and repeatedly fails
prepare_kswapd_sleep(), blocking the process from running and removing
itself from the waitqueue, which would let kswapd sleep.
So, the source of the problem is that we prevent kswapd from going to
sleep until there are processes waiting on the pfmemalloc_wait queue,
and a process waiting on a queue is guaranteed to be removed from the
queue only when it gets scheduled. This was done to make sure that no
process is left sleeping on pfmemalloc_wait when kswapd itself goes to
sleep.
However, it isn't necessary to postpone kswapd sleep until the
pfmemalloc_wait queue actually empties. To prevent processes from being
left sleeping, it's actually enough to guarantee that all processes
waiting on pfmemalloc_wait queue have been woken up by the time we put
kswapd to sleep.
This patch therefore fixes this issue by substituting 'wake_up' with
'wake_up_all' and removing 'return false' in the code snippet from
prepare_kswapd_sleep() above. Note that if any process puts itself in
the queue after this waitqueue_active() check, or after the wake up
itself, it means that the process will also wake up kswapd - and since
we are under prepare_to_wait(), the wake up won't be missed. Also we
update the comment prepare_kswapd_sleep() to hopefully more clearly
describe the races it is preventing.
Fixes:
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Johannes Weiner
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6b4f7799c6 |
mm: vmscan: invoke slab shrinkers from shrink_zone()
The slab shrinkers are currently invoked from the zonelist walkers in kswapd, direct reclaim, and zone reclaim, all of which roughly gauge the eligible LRU pages and assemble a nodemask to pass to NUMA-aware shrinkers, which then again have to walk over the nodemask. This is redundant code, extra runtime work, and fairly inaccurate when it comes to the estimation of actually scannable LRU pages. The code duplication will only get worse when making the shrinkers cgroup-aware and requiring them to have out-of-band cgroup hierarchy walks as well. Instead, invoke the shrinkers from shrink_zone(), which is where all reclaimers end up, to avoid this duplication. Take the count for eligible LRU pages out of get_scan_count(), which considers many more factors than just the availability of swap space, like zone_reclaimable_pages() currently does. Accumulate the number over all visited lruvecs to get the per-zone value. Some nodes have multiple zones due to memory addressing restrictions. To avoid putting too much pressure on the shrinkers, only invoke them once for each such node, using the class zone of the allocation as the pivot zone. For now, this integrates the slab shrinking better into the reclaim logic and gets rid of duplicative invocations from kswapd, direct reclaim, and zone reclaim. It also prepares for cgroup-awareness, allowing memcg-capable shrinkers to be added at the lruvec level without much duplication of both code and runtime work. This changes kswapd behavior, which used to invoke the shrinkers for each zone, but with scan ratios gathered from the entire node, resulting in meaningless pressure quantities on multi-zone nodes. Zone reclaim behavior also changes. It used to shrink slabs until the same amount of pages were shrunk as were reclaimed from the LRUs. Now it merely invokes the shrinkers once with the zone's scan ratio, which makes the shrinkers go easier on caches that implement aging and would prefer feeding back pressure from recently used slab objects to unused LRU pages. [vdavydov@parallels.com: assure class zone is populated] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
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2756d373a3 |
Merge branch 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup update from Tejun Heo: "cpuset got simplified a bit. cgroup core got a fix on unified hierarchy and grew some effective css related interfaces which will be used for blkio support for writeback IO traffic which is currently being worked on" * 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: implement cgroup_get_e_css() cgroup: add cgroup_subsys->css_e_css_changed() cgroup: add cgroup_subsys->css_released() cgroup: fix the async css offline wait logic in cgroup_subtree_control_write() cgroup: restructure child_subsys_mask handling in cgroup_subtree_control_write() cgroup: separate out cgroup_calc_child_subsys_mask() from cgroup_refresh_child_subsys_mask() cpuset: lock vs unlock typo cpuset: simplify cpuset_node_allowed API cpuset: convert callback_mutex to a spinlock |
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Vlastimil Babka
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ebff398017 |
mm, compaction: pass classzone_idx and alloc_flags to watermark checking
Compaction relies on zone watermark checks for decisions such as if it's worth to start compacting in compaction_suitable() or whether compaction should stop in compact_finished(). The watermark checks take classzone_idx and alloc_flags parameters, which are related to the memory allocation request. But from the context of compaction they are currently passed as 0, including the direct compaction which is invoked to satisfy the allocation request, and could therefore know the proper values. The lack of proper values can lead to mismatch between decisions taken during compaction and decisions related to the allocation request. Lack of proper classzone_idx value means that lowmem_reserve is not taken into account. This has manifested (during recent changes to deferred compaction) when DMA zone was used as fallback for preferred Normal zone. compaction_suitable() without proper classzone_idx would think that the watermarks are already satisfied, but watermark check in get_page_from_freelist() would fail. Because of this problem, deferring compaction has extra complexity that can be removed in the following patch. The issue (not confirmed in practice) with missing alloc_flags is opposite in nature. For allocations that include ALLOC_HIGH, ALLOC_HIGHER or ALLOC_CMA in alloc_flags (the last includes all MOVABLE allocations on CMA-enabled systems) the watermark checking in compaction with 0 passed will be stricter than in get_page_from_freelist(). In these cases compaction might be running for a longer time than is really needed. Another issue compaction_suitable() is that the check for "does the zone need compaction at all?" comes only after the check "does the zone have enough free free pages to succeed compaction". The latter considers extra pages for migration and can therefore in some situations fail and return COMPACT_SKIPPED, although the high-order allocation would succeed and we should return COMPACT_PARTIAL. This patch fixes these problems by adding alloc_flags and classzone_idx to struct compact_control and related functions involved in direct compaction and watermark checking. Where possible, all other callers of compaction_suitable() pass proper values where those are known. This is currently limited to classzone_idx, which is sometimes known in kswapd context. However, the direct reclaim callers should_continue_reclaim() and compaction_ready() do not currently know the proper values, so the coordination between reclaim and compaction may still not be as accurate as it could. This can be fixed later, if it's shown to be an issue. Additionaly the checks in compact_suitable() are reordered to address the second issue described above. The effect of this patch should be slightly better high-order allocation success rates and/or less compaction overhead, depending on the type of allocations and presence of CMA. It allows simplifying deferred compaction code in a followup patch. When testing with stress-highalloc, there was some slight improvement (which might be just due to variance) in success rates of non-THP-like allocations. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Christoph Lameter <cl@linux.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jamie Liu
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1da58ee2a0 |
mm: vmscan: count only dirty pages as congested
shrink_page_list() counts all pages with a mapping, including clean pages, toward nr_congested if they're on a write-congested BDI. shrink_inactive_list() then sets ZONE_CONGESTED if nr_dirty == nr_congested. Fix this apples-to-oranges comparison by only counting pages for nr_congested if they count for nr_dirty. Signed-off-by: Jamie Liu <jamieliu@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Pintu Kumar
|
8612c6639b |
mm/vmscan.c: replace printk with pr_err
This patch replaces printk(KERN_ERR..) with pr_err found under shrink_slab. Thus it also reduces one line extra because of formatting. Signed-off-by: Pintu Kumar <pintu.k@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov
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344736f29b |
cpuset: simplify cpuset_node_allowed API
Current cpuset API for checking if a zone/node is allowed to allocate
from looks rather awkward. We have hardwall and softwall versions of
cpuset_node_allowed with the softwall version doing literally the same
as the hardwall version if __GFP_HARDWALL is passed to it in gfp flags.
If it isn't, the softwall version may check the given node against the
enclosing hardwall cpuset, which it needs to take the callback lock to
do.
Such a distinction was introduced by commit
|
||
|
Johannes Weiner
|
b70a2a21dc |
mm: memcontrol: fix transparent huge page allocations under pressure
In a memcg with even just moderate cache pressure, success rates for
transparent huge page allocations drop to zero, wasting a lot of effort
that the allocator puts into assembling these pages.
The reason for this is that the memcg reclaim code was never designed for
higher-order charges. It reclaims in small batches until there is room
for at least one page. Huge page charges only succeed when these batches
add up over a series of huge faults, which is unlikely under any
significant load involving order-0 allocations in the group.
Remove that loop on the memcg side in favor of passing the actual reclaim
goal to direct reclaim, which is already set up and optimized to meet
higher-order goals efficiently.
This brings memcg's THP policy in line with the system policy: if the
allocator painstakingly assembles a hugepage, memcg will at least make an
honest effort to charge it. As a result, transparent hugepage allocation
rates amid cache activity are drastically improved:
vanilla patched
pgalloc 4717530.80 ( +0.00%) 4451376.40 ( -5.64%)
pgfault 491370.60 ( +0.00%) 225477.40 ( -54.11%)
pgmajfault 2.00 ( +0.00%) 1.80 ( -6.67%)
thp_fault_alloc 0.00 ( +0.00%) 531.60 (+100.00%)
thp_fault_fallback 749.00 ( +0.00%) 217.40 ( -70.88%)
[ Note: this may in turn increase memory consumption from internal
fragmentation, which is an inherent risk of transparent hugepages.
Some setups may have to adjust the memcg limits accordingly to
accomodate this - or, if the machine is already packed to capacity,
disable the transparent huge page feature. ]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Dave Hansen <dave@sr71.net>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
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Johannes Weiner
|
5705465174 |
mm: clean up zone flags
Page reclaim tests zone_is_reclaim_dirty(), but the site that actually sets this state does zone_set_flag(zone, ZONE_TAIL_LRU_DIRTY), sending the reader through layers indirection just to track down a simple bit. Remove all zone flag wrappers and just use bitops against zone->flags directly. It's just as readable and the lines are barely any longer. Also rename ZONE_TAIL_LRU_DIRTY to ZONE_DIRTY to match ZONE_WRITEBACK, and remove the zone_flags_t typedef. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
1f13ae399c |
mm: remove noisy remainder of the scan_unevictable interface
The deprecation warnings for the scan_unevictable interface triggers by
scripts doing `sysctl -a | grep something else'. This is annoying and not
helpful.
The interface has been defunct since
|
||
|
Vlastimil Babka
|
53853e2d2b |
mm, compaction: defer each zone individually instead of preferred zone
When direct sync compaction is often unsuccessful, it may become deferred
for some time to avoid further useless attempts, both sync and async.
Successful high-order allocations un-defer compaction, while further
unsuccessful compaction attempts prolong the compaction deferred period.
Currently the checking and setting deferred status is performed only on
the preferred zone of the allocation that invoked direct compaction. But
compaction itself is attempted on all eligible zones in the zonelist, so
the behavior is suboptimal and may lead both to scenarios where 1)
compaction is attempted uselessly, or 2) where it's not attempted despite
good chances of succeeding, as shown on the examples below:
1) A direct compaction with Normal preferred zone failed and set
deferred compaction for the Normal zone. Another unrelated direct
compaction with DMA32 as preferred zone will attempt to compact DMA32
zone even though the first compaction attempt also included DMA32 zone.
In another scenario, compaction with Normal preferred zone failed to
compact Normal zone, but succeeded in the DMA32 zone, so it will not
defer compaction. In the next attempt, it will try Normal zone which
will fail again, instead of skipping Normal zone and trying DMA32
directly.
2) Kswapd will balance DMA32 zone and reset defer status based on
watermarks looking good. A direct compaction with preferred Normal
zone will skip compaction of all zones including DMA32 because Normal
was still deferred. The allocation might have succeeded in DMA32, but
won't.
This patch makes compaction deferring work on individual zone basis
instead of preferred zone. For each zone, it checks compaction_deferred()
to decide if the zone should be skipped. If watermarks fail after
compacting the zone, defer_compaction() is called. The zone where
watermarks passed can still be deferred when the allocation attempt is
unsuccessful. When allocation is successful, compaction_defer_reset() is
called for the zone containing the allocated page. This approach should
approximate calling defer_compaction() only on zones where compaction was
attempted and did not yield allocated page. There might be corner cases
but that is inevitable as long as the decision to stop compacting dues not
guarantee that a page will be allocated.
Due to a new COMPACT_DEFERRED return value, some functions relying
implicitly on COMPACT_SKIPPED = 0 had to be updated, with comments made
more accurate. The did_some_progress output parameter of
__alloc_pages_direct_compact() is removed completely, as the caller
actually does not use it after compaction sets it - it is only considered
when direct reclaim sets it.
During testing on a two-node machine with a single very small Normal zone
on node 1, this patch has improved success rates in stress-highalloc
mmtests benchmark. The success here were previously made worse by commit
|
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Johannes Weiner
|
747db954ca |
mm: memcontrol: use page lists for uncharge batching
Pages are now uncharged at release time, and all sources of batched uncharges operate on lists of pages. Directly use those lists, and get rid of the per-task batching state. This also batches statistics accounting, in addition to the res counter charges, to reduce IRQ-disabling and re-enabling. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
0a31bc97c8 |
mm: memcontrol: rewrite uncharge API
The memcg uncharging code that is involved towards the end of a page's lifetime - truncation, reclaim, swapout, migration - is impressively complicated and fragile. Because anonymous and file pages were always charged before they had their page->mapping established, uncharges had to happen when the page type could still be known from the context; as in unmap for anonymous, page cache removal for file and shmem pages, and swap cache truncation for swap pages. However, these operations happen well before the page is actually freed, and so a lot of synchronization is necessary: - Charging, uncharging, page migration, and charge migration all need to take a per-page bit spinlock as they could race with uncharging. - Swap cache truncation happens during both swap-in and swap-out, and possibly repeatedly before the page is actually freed. This means that the memcg swapout code is called from many contexts that make no sense and it has to figure out the direction from page state to make sure memory and memory+swap are always correctly charged. - On page migration, the old page might be unmapped but then reused, so memcg code has to prevent untimely uncharging in that case. Because this code - which should be a simple charge transfer - is so special-cased, it is not reusable for replace_page_cache(). But now that charged pages always have a page->mapping, introduce mem_cgroup_uncharge(), which is called after the final put_page(), when we know for sure that nobody is looking at the page anymore. For page migration, introduce mem_cgroup_migrate(), which is called after the migration is successful and the new page is fully rmapped. Because the old page is no longer uncharged after migration, prevent double charges by decoupling the page's memcg association (PCG_USED and pc->mem_cgroup) from the page holding an actual charge. The new bits PCG_MEM and PCG_MEMSW represent the respective charges and are transferred to the new page during migration. mem_cgroup_migrate() is suitable for replace_page_cache() as well, which gets rid of mem_cgroup_replace_page_cache(). However, care needs to be taken because both the source and the target page can already be charged and on the LRU when fuse is splicing: grab the page lock on the charge moving side to prevent changing pc->mem_cgroup of a page under migration. Also, the lruvecs of both pages change as we uncharge the old and charge the new during migration, and putback may race with us, so grab the lru lock and isolate the pages iff on LRU to prevent races and ensure the pages are on the right lruvec afterward. Swap accounting is massively simplified: because the page is no longer uncharged as early as swap cache deletion, a new mem_cgroup_swapout() can transfer the page's memory+swap charge (PCG_MEMSW) to the swap entry before the final put_page() in page reclaim. Finally, page_cgroup changes are now protected by whatever protection the page itself offers: anonymous pages are charged under the page table lock, whereas page cache insertions, swapin, and migration hold the page lock. Uncharging happens under full exclusion with no outstanding references. Charging and uncharging also ensure that the page is off-LRU, which serializes against charge migration. Remove the very costly page_cgroup lock and set pc->flags non-atomically. [mhocko@suse.cz: mem_cgroup_charge_statistics needs preempt_disable] [vdavydov@parallels.com: fix flags definition] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vladimir Davydov <vdavydov@parallels.com> Tested-by: Jet Chen <jet.chen@intel.com> Acked-by: Michal Hocko <mhocko@suse.cz> Tested-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jerome Marchand
|
2ab051e11b |
memcg, vmscan: Fix forced scan of anonymous pages
When memory cgoups are enabled, the code that decides to force to scan anonymous pages in get_scan_count() compares global values (free, high_watermark) to a value that is restricted to a memory cgroup (file). It make the code over-eager to force anon scan. For instance, it will force anon scan when scanning a memcg that is mainly populated by anonymous page, even when there is plenty of file pages to get rid of in others memcgs, even when swappiness == 0. It breaks user's expectation about swappiness and hurts performance. This patch makes sure that forced anon scan only happens when there not enough file pages for the all zone, not just in one random memcg. [hannes@cmpxchg.org: cleanups] Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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|
Jerome Marchand
|
7c0db9e917 |
mm, vmscan: fix an outdated comment still mentioning get_scan_ratio
Quite a while ago, get_scan_ratio() has been renamed get_scan_count(), however a comment in shrink_active_list() still mention it. This patch fixes the outdated comment. Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
0d5d823ab4 |
mm: move zone->pages_scanned into a vmstat counter
zone->pages_scanned is a write-intensive cache line during page reclaim
and it's also updated during page free. Move the counter into vmstat to
take advantage of the per-cpu updates and do not update it in the free
paths unless necessary.
On a small UMA machine running tiobench the difference is marginal. On
a 4-node machine the overhead is more noticable. Note that automatic
NUMA balancing was disabled for this test as otherwise the system CPU
overhead is unpredictable.
3.16.0-rc3 3.16.0-rc3 3.16.0-rc3
vanillarearrange-v5 vmstat-v5
User 746.94 759.78 774.56
System 65336.22 58350.98 32847.27
Elapsed 27553.52 27282.02 27415.04
Note that the overhead reduction will vary depending on where exactly
pages are allocated and freed.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
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Wang Sheng-Hui
|
d0480be44a |
mm: update the description for vm_total_pages
vm_total_pages is calculated by nr_free_pagecache_pages(), which counts the number of pages which are beyond the high watermark within all zones. So vm_total_pages is not equal to total number of pages which the VM controls. Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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|
Johannes Weiner
|
ee814fe23d |
mm: vmscan: clean up struct scan_control
Reorder the members by input and output, then turn the individual integers for may_writepage, may_unmap, may_swap, compaction_ready, hibernation_mode into bit fields to save stack space: +72/-296 -224 kswapd 104 176 +72 try_to_free_pages 80 56 -24 try_to_free_mem_cgroup_pages 80 56 -24 shrink_all_memory 88 64 -24 reclaim_clean_pages_from_list 168 144 -24 mem_cgroup_shrink_node_zone 104 80 -24 __zone_reclaim 176 152 -24 balance_pgdat 152 - -152 Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Mel Gorman <mgorman@suse.de> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Johannes Weiner
|
02695175c7 |
mm: vmscan: move swappiness out of scan_control
Swappiness is determined for each scanned memcg individually in shrink_zone() and is not a parameter that applies throughout the reclaim scan. Move it out of struct scan_control to prevent accidental use of a stale value. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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|
Johannes Weiner
|
2344d7e44b |
mm: vmscan: remove all_unreclaimable()
Direct reclaim currently calls shrink_zones() to reclaim all members of a zonelist, and if that wasn't successful it does another pass through the same zonelist to check overall reclaimability. Just check reclaimability in shrink_zones() directly and propagate the result through the return value. Then remove all_unreclaimable(). Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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|
Johannes Weiner
|
0b06496a33 |
mm: vmscan: rework compaction-ready signaling in direct reclaim
Page reclaim for a higher-order page runs until compaction is ready, then aborts and signals this situation through the return value of shrink_zones(). This is an oddly specific signal to encode in the return value of shrink_zones(), though, and can be quite confusing. Introduce sc->compaction_ready and signal the compactability of the zones out-of-band to free up the return value of shrink_zones() for actual zone reclaimability. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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|
Johannes Weiner
|
8d07429319 |
mm: vmscan: remove remains of kswapd-managed zone->all_unreclaimable
shrink_zones() has a special branch to skip the all_unreclaimable()
check during hibernation, because a frozen kswapd can't mark a zone
unreclaimable.
But ever since commit
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|
Linus Torvalds
|
16b9057804 |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs updates from Al Viro:
"This the bunch that sat in -next + lock_parent() fix. This is the
minimal set; there's more pending stuff.
In particular, I really hope to get acct.c fixes merged this cycle -
we need that to deal sanely with delayed-mntput stuff. In the next
pile, hopefully - that series is fairly short and localized
(kernel/acct.c, fs/super.c and fs/namespace.c). In this pile: more
iov_iter work. Most of prereqs for ->splice_write with sane locking
order are there and Kent's dio rewrite would also fit nicely on top of
this pile"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (70 commits)
lock_parent: don't step on stale ->d_parent of all-but-freed one
kill generic_file_splice_write()
ceph: switch to iter_file_splice_write()
shmem: switch to iter_file_splice_write()
nfs: switch to iter_splice_write_file()
fs/splice.c: remove unneeded exports
ocfs2: switch to iter_file_splice_write()
->splice_write() via ->write_iter()
bio_vec-backed iov_iter
optimize copy_page_{to,from}_iter()
bury generic_file_aio_{read,write}
lustre: get rid of messing with iovecs
ceph: switch to ->write_iter()
ceph_sync_direct_write: stop poking into iov_iter guts
ceph_sync_read: stop poking into iov_iter guts
new helper: copy_page_from_iter()
fuse: switch to ->write_iter()
btrfs: switch to ->write_iter()
ocfs2: switch to ->write_iter()
xfs: switch to ->write_iter()
...
|
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|
Linus Torvalds
|
b738d76465 |
Don't trigger congestion wait on dirty-but-not-writeout pages
shrink_inactive_list() used to wait 0.1s to avoid congestion when all
the pages that were isolated from the inactive list were dirty but not
under active writeback. That makes no real sense, and apparently causes
major interactivity issues under some loads since 3.11.
The ostensible reason for it was to wait for kswapd to start writing
pages, but that seems questionable as well, since the congestion wait
code seems to trigger for kswapd itself as well. Also, the logic behind
delaying anything when we haven't actually started writeback is not
clear - it only delays actually starting that writeback.
We'll still trigger the congestion waiting if
(a) the process is kswapd, and we hit pages flagged for immediate
reclaim
(b) the process is not kswapd, and the zone backing dev writeback is
actually congested.
This probably needs to be revisited, but as it is this fixes a reported
regression.
Reported-by: Felipe Contreras <felipe.contreras@gmail.com>
Pinpointed-by: Hillf Danton <dhillf@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
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Mitchel Humpherys
|
b1de0d139c |
mm: convert some level-less printks to pr_*
printk is meant to be used with an associated log level. There are some instances of printk scattered around the mm code where the log level is missing. Add a log level and adhere to suggestions by scripts/checkpatch.pl by moving to the pr_* macros. Also add the typical pr_fmt definition so that print statements can be easily traced back to the modules where they occur, correlated one with another, etc. This will require the removal of some (now redundant) prefixes on a few print statements. Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
Michal Hocko
|
688eb988d1 |
vmscan: memcg: always use swappiness of the reclaimed memcg
Memory reclaim always uses swappiness of the reclaim target memcg (origin of the memory pressure) or vm_swappiness for global memory reclaim. This behavior was consistent (except for difference between global and hard limit reclaim) because swappiness was enforced to be consistent within each memcg hierarchy. After "mm: memcontrol: remove hierarchy restrictions for swappiness and oom_control" each memcg can have its own swappiness independent of hierarchical parents, though, so the consistency guarantee is gone. This can lead to an unexpected behavior. Say that a group is explicitly configured to not swapout by memory.swappiness=0 but its memory gets swapped out anyway when the memory pressure comes from its parent with a It is also unexpected that the knob is meaningless without setting the hard limit which would trigger the reclaim and enforce the swappiness. There are setups where the hard limit is configured higher in the hierarchy by an administrator and children groups are under control of somebody else who is interested in the swapout behavior but not necessarily about the memory limit. From a semantic point of view swappiness is an attribute defining anon vs. file proportional scanning of LRU which is memcg specific (unlike charges which are propagated up the hierarchy) so it should be applied to the particular memcg's LRU regardless where the memory pressure comes from. This patch removes vmscan_swappiness() and stores the swappiness into the scan_control structure. mem_cgroup_swappiness is then used to provide the correct value before shrink_lruvec is called. The global vm_swappiness is used for the root memcg. [hughd@google.com: oopses immediately when booted with cgroup_disable=memory] Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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|
Johannes Weiner
|
71abdc15ad |
mm: vmscan: clear kswapd's special reclaim powers before exiting
When kswapd exits, it can end up taking locks that were previously held
by allocating tasks while they waited for reclaim. Lockdep currently
warns about this:
On Wed, May 28, 2014 at 06:06:34PM +0800, Gu Zheng wrote:
> inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-R} usage.
> kswapd2/1151 [HC0[0]:SC0[0]:HE1:SE1] takes:
> (&sig->group_rwsem){+++++?}, at: exit_signals+0x24/0x130
> {RECLAIM_FS-ON-W} state was registered at:
> mark_held_locks+0xb9/0x140
> lockdep_trace_alloc+0x7a/0xe0
> kmem_cache_alloc_trace+0x37/0x240
> flex_array_alloc+0x99/0x1a0
> cgroup_attach_task+0x63/0x430
> attach_task_by_pid+0x210/0x280
> cgroup_procs_write+0x16/0x20
> cgroup_file_write+0x120/0x2c0
> vfs_write+0xc0/0x1f0
> SyS_write+0x4c/0xa0
> tracesys+0xdd/0xe2
> irq event stamp: 49
> hardirqs last enabled at (49): _raw_spin_unlock_irqrestore+0x36/0x70
> hardirqs last disabled at (48): _raw_spin_lock_irqsave+0x2b/0xa0
> softirqs last enabled at (0): copy_process.part.24+0x627/0x15f0
> softirqs last disabled at (0): (null)
>
> other info that might help us debug this:
> Possible unsafe locking scenario:
>
> CPU0
> ----
> lock(&sig->group_rwsem);
> <Interrupt>
> lock(&sig->group_rwsem);
>
> *** DEADLOCK ***
>
> no locks held by kswapd2/1151.
>
> stack backtrace:
> CPU: 30 PID: 1151 Comm: kswapd2 Not tainted 3.10.39+ #4
> Call Trace:
> dump_stack+0x19/0x1b
> print_usage_bug+0x1f7/0x208
> mark_lock+0x21d/0x2a0
> __lock_acquire+0x52a/0xb60
> lock_acquire+0xa2/0x140
> down_read+0x51/0xa0
> exit_signals+0x24/0x130
> do_exit+0xb5/0xa50
> kthread+0xdb/0x100
> ret_from_fork+0x7c/0xb0
This is because the kswapd thread is still marked as a reclaimer at the
time of exit. But because it is exiting, nobody is actually waiting on
it to make reclaim progress anymore, and it's nothing but a regular
thread at this point. Be tidy and strip it of all its powers
(PF_MEMALLOC, PF_SWAPWRITE, PF_KSWAPD, and the lockdep reclaim state)
before returning from the thread function.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Mel Gorman
|
1a501907bb |
mm: vmscan: use proportional scanning during direct reclaim and full scan at DEF_PRIORITY
Commit "mm: vmscan: obey proportional scanning requirements for kswapd"
ensured that file/anon lists were scanned proportionally for reclaim from
kswapd but ignored it for direct reclaim. The intent was to minimse
direct reclaim latency but Yuanhan Liu pointer out that it substitutes one
long stall for many small stalls and distorts aging for normal workloads
like streaming readers/writers. Hugh Dickins pointed out that a
side-effect of the same commit was that when one LRU list dropped to zero
that the entirety of the other list was shrunk leading to excessive
reclaim in memcgs. This patch scans the file/anon lists proportionally
for direct reclaim to similarly age page whether reclaimed by kswapd or
direct reclaim but takes care to abort reclaim if one LRU drops to zero
after reclaiming the requested number of pages.
Based on ext4 and using the Intel VM scalability test
3.15.0-rc5 3.15.0-rc5
shrinker proportion
Unit lru-file-readonce elapsed 5.3500 ( 0.00%) 5.4200 ( -1.31%)
Unit lru-file-readonce time_range 0.2700 ( 0.00%) 0.1400 ( 48.15%)
Unit lru-file-readonce time_stddv 0.1148 ( 0.00%) 0.0536 ( 53.33%)
Unit lru-file-readtwice elapsed 8.1700 ( 0.00%) 8.1700 ( 0.00%)
Unit lru-file-readtwice time_range 0.4300 ( 0.00%) 0.2300 ( 46.51%)
Unit lru-file-readtwice time_stddv 0.1650 ( 0.00%) 0.0971 ( 41.16%)
The test cases are running multiple dd instances reading sparse files. The results are within
the noise for the small test machine. The impact of the patch is more noticable from the vmstats
3.15.0-rc5 3.15.0-rc5
shrinker proportion
Minor Faults 35154 36784
Major Faults 611 1305
Swap Ins 394 1651
Swap Outs 4394 5891
Allocation stalls 118616 44781
Direct pages scanned 4935171 4602313
Kswapd pages scanned 15921292 16258483
Kswapd pages reclaimed 15913301 16248305
Direct pages reclaimed 4933368 4601133
Kswapd efficiency 99% 99%
Kswapd velocity 670088.047 682555.961
Direct efficiency 99% 99%
Direct velocity 207709.217 193212.133
Percentage direct scans 23% 22%
Page writes by reclaim 4858.000 6232.000
Page writes file 464 341
Page writes anon 4394 5891
Note that there are fewer allocation stalls even though the amount
of direct reclaim scanning is very approximately the same.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Tested-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
Jianyu Zhan
|
4be89a3460 |
mm/vmscan.c: use DIV_ROUND_UP for calculation of zone's balance_gap and correct comments.
Currently, we use (zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) / KSWAPD_ZONE_BALANCE_GAP_RATIO to avoid a zero gap value. It's better to use DIV_ROUND_UP macro for neater code and clear meaning. Besides, the gap value is calculated against the per-zone "managed pages", not "present pages". This patch also corrects the comment and do some rephrasing. Signed-off-by: Jianyu Zhan <nasa4836@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
b745bc85f2 |
mm: page_alloc: convert hot/cold parameter and immediate callers to bool
cold is a bool, make it one. Make the likely case the "if" part of the block instead of the else as according to the optimisation manual this is preferred. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jan Kara <jack@suse.cz> Cc: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
Dave Hansen
|
df9024a8c5 |
mm: shrinker: add nid to tracepoint output
Now that we are doing NUMA-aware shrinking, and can have shrinkers running in parallel, or working on individual nodes, it seems like we should also be sticking the node in the output. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Dave Chinner <david@fromorbit.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Dave Hansen
|
7fe7047597 |
mm: shrinker trace points: fix negatives
I was looking at a trace of the slab shrinkers (attachment in this comment): https://bugs.freedesktop.org/show_bug.cgi?id=72742#c67 and noticed that "total_scan" can go negative in some cases. We used to dump out the "total_scan" variable directly, but some of the shrinker modifications along the way changed that. This patch just dumps it out directly, again. It doesn't make any sense to derive it from new_nr and nr any more since there are now other shrinkers that can be running in parallel and mucking with those values. Here's an example of the negative numbers in the output: > kswapd0-840 [000] 160.869398: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 10 new scan count 39 total_scan 29 last shrinker return val 256 > kswapd0-840 [000] 160.869618: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 39 new scan count 102 total_scan 63 last shrinker return val 256 > kswapd0-840 [000] 160.870031: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 102 new scan count 47 total_scan -55 last shrinker return val 768 > kswapd0-840 [000] 160.870464: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 47 new scan count 45 total_scan -2 last shrinker return val 768 > kswapd0-840 [000] 163.384144: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 45 new scan count 56 total_scan 11 last shrinker return val 0 > kswapd0-840 [000] 163.384297: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 56 new scan count 15 total_scan -41 last shrinker return val 256 > kswapd0-840 [000] 163.384414: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 15 new scan count 117 total_scan 102 last shrinker return val 0 > kswapd0-840 [000] 163.384657: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 117 new scan count 36 total_scan -81 last shrinker return val 512 > kswapd0-840 [000] 163.384880: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 36 new scan count 111 total_scan 75 last shrinker return val 256 > kswapd0-840 [000] 163.385256: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 111 new scan count 34 total_scan -77 last shrinker return val 768 > kswapd0-840 [000] 163.385598: mm_shrink_slab_end: i915_gem_inactive_scan+0x0 0xffff8800037cbc68: unused scan count 34 new scan count 122 total_scan 88 last shrinker return val 512 Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Dave Chinner <david@fromorbit.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
NeilBrown
|
399ba0b956 |
mm/vmscan.c: avoid throttling reclaim for loop-back nfsd threads
When a loopback NFS mount is active and the backing device for the NFS mount becomes congested, that can impose throttling delays on the nfsd threads. These delays significantly reduce throughput and so the NFS mount remains congested. This results in a livelock and the reduced throughput persists. This livelock has been found in testing with the 'wait_iff_congested' call, and could possibly be caused by the 'congestion_wait' call. This livelock is similar to the deadlock which justified the introduction of PF_LESS_THROTTLE, and the same flag can be used to remove this livelock. To minimise the impact of the change, we still throttle nfsd when the filesystem it is writing to is congested, but not when some separate filesystem (e.g. the NFS filesystem) is congested. Signed-off-by: NeilBrown <neilb@suse.de> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Mel Gorman
|
675becce15 |
mm: vmscan: do not throttle based on pfmemalloc reserves if node has no ZONE_NORMAL
throttle_direct_reclaim() is meant to trigger during swap-over-network during which the min watermark is treated as a pfmemalloc reserve. It throttes on the first node in the zonelist but this is flawed. The user-visible impact is that a process running on CPU whose local memory node has no ZONE_NORMAL will stall for prolonged periods of time, possibly indefintely. This is due to throttle_direct_reclaim thinking the pfmemalloc reserves are depleted when in fact they don't exist on that node. On a NUMA machine running a 32-bit kernel (I know) allocation requests from CPUs on node 1 would detect no pfmemalloc reserves and the process gets throttled. This patch adjusts throttling of direct reclaim to throttle based on the first node in the zonelist that has a usable ZONE_NORMAL or lower zone. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Vladimir Davydov
|
bfc8c90139 |
mem-hotplug: implement get/put_online_mems
kmem_cache_{create,destroy,shrink} need to get a stable value of
cpu/node online mask, because they init/destroy/access per-cpu/node
kmem_cache parts, which can be allocated or destroyed on cpu/mem
hotplug. To protect against cpu hotplug, these functions use
{get,put}_online_cpus. However, they do nothing to synchronize with
memory hotplug - taking the slab_mutex does not eliminate the
possibility of race as described in patch 2.
What we need there is something like get_online_cpus, but for memory.
We already have lock_memory_hotplug, which serves for the purpose, but
it's a bit of a hammer right now, because it's backed by a mutex. As a
result, it imposes some limitations to locking order, which are not
desirable, and can't be used just like get_online_cpus. That's why in
patch 1 I substitute it with get/put_online_mems, which work exactly
like get/put_online_cpus except they block not cpu, but memory hotplug.
[ v1 can be found at https://lkml.org/lkml/2014/4/6/68. I NAK'ed it by
myself, because it used an rw semaphore for get/put_online_mems,
making them dead lock prune. ]
This patch (of 2):
{un}lock_memory_hotplug, which is used to synchronize against memory
hotplug, is currently backed by a mutex, which makes it a bit of a
hammer - threads that only want to get a stable value of online nodes
mask won't be able to proceed concurrently. Also, it imposes some
strong locking ordering rules on it, which narrows down the set of its
usage scenarios.
This patch introduces get/put_online_mems, which are the same as
get/put_online_cpus, but for memory hotplug, i.e. executing a code
inside a get/put_online_mems section will guarantee a stable value of
online nodes, present pages, etc.
lock_memory_hotplug()/unlock_memory_hotplug() are removed altogether.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
Suleiman Souhlal
|
6f04f48dc9 |
mm: only force scan in reclaim when none of the LRUs are big enough.
Prior to this change, we would decide whether to force scan a LRU during
reclaim if that LRU itself was too small for the current priority.
However, this can lead to the file LRU getting force scanned even if
there are a lot of anonymous pages we can reclaim, leading to hot file
pages getting needlessly reclaimed.
To address this, we instead only force scan when none of the reclaimable
LRUs are big enough.
Gives huge improvements with zswap. For example, when doing -j20 kernel
build in a 500MB container with zswap enabled, runtime (in seconds) is
greatly reduced:
x without this change
+ with this change
N Min Max Median Avg Stddev
x 5 700.997 790.076 763.928 754.05 39.59493
+ 5 141.634 197.899 155.706 161.9 21.270224
Difference at 95.0% confidence
-592.15 +/- 46.3521
-78.5293% +/- 6.14709%
(Student's t, pooled s = 31.7819)
Should also give some improvements in regular (non-zswap) swap cases.
Yes, hughd found significant speedup using regular swap, with several
memcgs under pressure; and it should also be effective in the non-memcg
case, whenever one or another zone LRU is forced too small.
Signed-off-by: Suleiman Souhlal <suleiman@google.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Luigi Semenzato <semenzato@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
Al Viro
|
8174202b34 |
write_iter variants of {__,}generic_file_aio_write()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
||
|
Johannes Weiner
|
623762517e |
revert "mm: vmscan: do not swap anon pages just because free+file is low"
This reverts commit
|
||
Christoph Lameter
|
83da751005 |
vmscan: reclaim_clean_pages_from_list() must use mod_zone_page_state()
Seems to be called with preemption enabled. Therefore it must use mod_zone_page_state instead. Signed-off-by: Christoph Lameter <cl@linux.com> Reported-by: Grygorii Strashko <grygorii.strashko@ti.com> Tested-by: Grygorii Strashko <grygorii.strashko@ti.com> Cc: Tejun Heo <tj@kernel.org> Cc: Santosh Shilimkar <santosh.shilimkar@ti.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
0bf1457f0c |
mm: vmscan: do not swap anon pages just because free+file is low
Page reclaim force-scans / swaps anonymous pages when file cache drops
below the high watermark of a zone in order to prevent what little cache
remains from thrashing.
However, on bigger machines the high watermark value can be quite large
and when the workload is dominated by a static anonymous/shmem set, the
file set might just be a small window of used-once cache. In such
situations, the VM starts swapping heavily when instead it should be
recycling the no longer used cache.
This is a longer-standing problem, but it's more likely to trigger after
commit
|
||
Weijie Yang
|
9bbc04eeb0 |
mm/vmscan: do not check compaction_ready on promoted zones
We abort direct reclaim if we find the zone is ready for compaction. Sometimes the zone is just a promoted highmem zone to force a scan of highmem, which is not the intended zone the caller want to allocate a page from. In this situation, setting aborted_reclaim to indicate the caller turned back to retry the allocation is waste of time and could cause a loop in __alloc_pages_slowpath(). This patch does not check compaction_ready() on promoted zones to avoid the above situation. Only set aborted_reclaim if the caller intended zone is ready for compaction. Signed-off-by: Weijie Yang <weijie.yang@samsung.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Weijie Yang
|
619d0d76c1 |
mm/vmscan: restore sc->gfp_mask after promoting it to __GFP_HIGHMEM
We promote sc->gfp_mask to __GFP_HIGHMEM to forcibly scan highmem if
there are too many buffer_heads pinning highmem. See
|
||
|
Johannes Weiner
|
a528910e12 |
mm: thrash detection-based file cache sizing
The VM maintains cached filesystem pages on two types of lists. One list holds the pages recently faulted into the cache, the other list holds pages that have been referenced repeatedly on that first list. The idea is to prefer reclaiming young pages over those that have shown to benefit from caching in the past. We call the recently usedbut ultimately was not significantly better than a FIFO policy and still thrashed cache based on eviction speed, rather than actual demand for cache. This patch solves one half of the problem by decoupling the ability to detect working set changes from the inactive list size. By maintaining a history of recently evicted file pages it can detect frequently used pages with an arbitrarily small inactive list size, and subsequently apply pressure on the active list based on actual demand for cache, not just overall eviction speed. Every zone maintains a counter that tracks inactive list aging speed. When a page is evicted, a snapshot of this counter is stored in the now-empty page cache radix tree slot. On refault, the minimum access distance of the page can be assessed, to evaluate whether the page should be part of the active list or not. This fixes the VM's blindness towards working set changes in excess of the inactive list. And it's the foundation to further improve the protection ability and reduce the minimum inactive list size of 50%. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Reviewed-by: Bob Liu <bob.liu@oracle.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Luigi Semenzato <semenzato@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Metin Doslu <metin@citusdata.com> Cc: Michel Lespinasse <walken@google.com> Cc: Ozgun Erdogan <ozgun@citusdata.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <klamm@yandex-team.ru> Cc: Ryan Mallon <rmallon@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Johannes Weiner
|
91b0abe36a |
mm + fs: store shadow entries in page cache
Reclaim will be leaving shadow entries in the page cache radix tree upon evicting the real page. As those pages are found from the LRU, an iput() can lead to the inode being freed concurrently. At this point, reclaim must no longer install shadow pages because the inode freeing code needs to ensure the page tree is really empty. Add an address_space flag, AS_EXITING, that the inode freeing code sets under the tree lock before doing the final truncate. Reclaim will check for this flag before installing shadow pages. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Bob Liu <bob.liu@oracle.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Luigi Semenzato <semenzato@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Metin Doslu <metin@citusdata.com> Cc: Michel Lespinasse <walken@google.com> Cc: Ozgun Erdogan <ozgun@citusdata.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <klamm@yandex-team.ru> Cc: Ryan Mallon <rmallon@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Vladimir Davydov
|
d5bc5fd3fc |
mm: vmscan: shrink_slab: rename max_pass -> freeable
The name `max_pass' is misleading, because this variable actually keeps the estimate number of freeable objects, not the maximal number of objects we can scan in this pass, which can be twice that. Rename it to reflect its actual meaning. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Vladimir Davydov
|
3115cd9145 |
mm: vmscan: remove shrink_control arg from do_try_to_free_pages()
There is no need passing on a shrink_control struct from try_to_free_pages() and friends to do_try_to_free_pages() and then to shrink_zones(), because it is only used in shrink_zones() and the only field initialized on the top level is gfp_mask, which is always equal to scan_control.gfp_mask. So let's move shrink_control initialization to shrink_zones(). Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <dchinner@redhat.com> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Vladimir Davydov
|
65ec02cb9a |
mm: vmscan: move call to shrink_slab() to shrink_zones()
This reduces the indentation level of do_try_to_free_pages() and removes extra loop over all eligible zones counting the number of on-LRU pages. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Reviewed-by: Glauber Costa <glommer@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <dchinner@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov
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99120b772b |
mm: vmscan: respect NUMA policy mask when shrinking slab on direct reclaim
When direct reclaim is executed by a process bound to a set of NUMA nodes, we should scan only those nodes when possible, but currently we will scan kmem from all online nodes even if the kmem shrinker is NUMA aware. That said, binding a process to a particular NUMA node won't prevent it from shrinking inode/dentry caches from other nodes, which is not good. Fix this. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Dave Chinner <dchinner@redhat.com> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Johannes Weiner
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a1c3bfb2f6 |
mm/page-writeback.c: do not count anon pages as dirtyable memory
The VM is currently heavily tuned to avoid swapping. Whether that is good or bad is a separate discussion, but as long as the VM won't swap to make room for dirty cache, we can not consider anonymous pages when calculating the amount of dirtyable memory, the baseline to which dirty_background_ratio and dirty_ratio are applied. A simple workload that occupies a significant size (40+%, depending on memory layout, storage speeds etc.) of memory with anon/tmpfs pages and uses the remainder for a streaming writer demonstrates this problem. In that case, the actual cache pages are a small fraction of what is considered dirtyable overall, which results in an relatively large portion of the cache pages to be dirtied. As kswapd starts rotating these, random tasks enter direct reclaim and stall on IO. Only consider free pages and file pages dirtyable. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Tejun Heo <tj@kernel.org> Tested-by: Tejun Heo <tj@kernel.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov
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ec97097bca |
mm: vmscan: call NUMA-unaware shrinkers irrespective of nodemask
If a shrinker is not NUMA-aware, shrink_slab() should call it exactly once with nid=0, but currently it is not true: if node 0 is not set in the nodemask or if it is not online, we will not call such shrinkers at all. As a result some slabs will be left untouched under some circumstances. Let us fix it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Reported-by: Dave Chinner <dchinner@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vladimir Davydov
|
0b1fb40a3b |
mm: vmscan: shrink all slab objects if tight on memory
When reclaiming kmem, we currently don't scan slabs that have less than
batch_size objects (see shrink_slab_node()):
while (total_scan >= batch_size) {
shrinkctl->nr_to_scan = batch_size;
shrinker->scan_objects(shrinker, shrinkctl);
total_scan -= batch_size;
}
If there are only a few shrinkers available, such a behavior won't cause
any problems, because the batch_size is usually small, but if we have a
lot of slab shrinkers, which is perfectly possible since FS shrinkers
are now per-superblock, we can end up with hundreds of megabytes of
practically unreclaimable kmem objects. For instance, mounting a
thousand of ext2 FS images with a hundred of files in each and iterating
over all the files using du(1) will result in about 200 Mb of FS caches
that cannot be dropped even with the aid of the vm.drop_caches sysctl!
This problem was initially pointed out by Glauber Costa [*]. Glauber
proposed to fix it by making the shrink_slab() always take at least one
pass, to put it simply, turning the scan loop above to a do{}while()
loop. However, this proposal was rejected, because it could result in
more aggressive and frequent slab shrinking even under low memory
pressure when total_scan is naturally very small.
This patch is a slightly modified version of Glauber's approach.
Similarly to Glauber's patch, it makes shrink_slab() scan less than
batch_size objects, but only if the total number of objects we want to
scan (total_scan) is greater than the total number of objects available
(max_pass). Since total_scan is biased as half max_pass if the current
delta change is small:
if (delta < max_pass / 4)
total_scan = min(total_scan, max_pass / 2);
this is only possible if we are scanning at high prio. That said, this
patch shouldn't change the vmscan behaviour if the memory pressure is
low, but if we are tight on memory, we will do our best by trying to
reclaim all available objects, which sounds reasonable.
[*] http://www.spinics.net/lists/cgroups/msg06913.html
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Glauber Costa <glommer@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Sasha Levin
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309381feae |
mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE
Most of the VM_BUG_ON assertions are performed on a page. Usually, when one of these assertions fails we'll get a BUG_ON with a call stack and the registers. I've recently noticed based on the requests to add a small piece of code that dumps the page to various VM_BUG_ON sites that the page dump is quite useful to people debugging issues in mm. This patch adds a VM_BUG_ON_PAGE(cond, page) which beyond doing what VM_BUG_ON() does, also dumps the page before executing the actual BUG_ON. [akpm@linux-foundation.org: fix up includes] Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrew Vagin
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ae39332162 |
mm/vmscan.c: don't forget to free shrinker->nr_deferred
This leak was added by commit
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Rafael Aquini
|
117aad1e9e |
mm: avoid reinserting isolated balloon pages into LRU lists
Isolated balloon pages can wrongly end up in LRU lists when migrate_pages() finishes its round without draining all the isolated page list. The same issue can happen when reclaim_clean_pages_from_list() tries to reclaim pages from an isolated page list, before migration, in the CMA path. Such balloon page leak opens a race window against LRU lists shrinkers that leads us to the following kernel panic: BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 IP: [<ffffffff810c2625>] shrink_page_list+0x24e/0x897 PGD 3cda2067 PUD 3d713067 PMD 0 Oops: 0000 [#1] SMP CPU: 0 PID: 340 Comm: kswapd0 Not tainted 3.12.0-rc1-22626-g4367597 #87 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 RIP: shrink_page_list+0x24e/0x897 RSP: 0000:ffff88003da499b8 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff88003e82bd60 RCX: 00000000000657d5 RDX: 0000000000000000 RSI: 000000000000031f RDI: ffff88003e82bd40 RBP: ffff88003da49ab0 R08: 0000000000000001 R09: 0000000081121a45 R10: ffffffff81121a45 R11: ffff88003c4a9a28 R12: ffff88003e82bd40 R13: ffff88003da0e800 R14: 0000000000000001 R15: ffff88003da49d58 FS: 0000000000000000(0000) GS:ffff88003fc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000067d9000 CR3: 000000003ace5000 CR4: 00000000000407b0 Call Trace: shrink_inactive_list+0x240/0x3de shrink_lruvec+0x3e0/0x566 __shrink_zone+0x94/0x178 shrink_zone+0x3a/0x82 balance_pgdat+0x32a/0x4c2 kswapd+0x2f0/0x372 kthread+0xa2/0xaa ret_from_fork+0x7c/0xb0 Code: 80 7d 8f 01 48 83 95 68 ff ff ff 00 4c 89 e7 e8 5a 7b 00 00 48 85 c0 49 89 c5 75 08 80 7d 8f 00 74 3e eb 31 48 8b 80 18 01 00 00 <48> 8b 74 0d 48 8b 78 30 be 02 00 00 00 ff d2 eb RIP [<ffffffff810c2625>] shrink_page_list+0x24e/0x897 RSP <ffff88003da499b8> CR2: 0000000000000028 ---[ end trace 703d2451af6ffbfd ]--- Kernel panic - not syncing: Fatal exception This patch fixes the issue, by assuring the proper tests are made at putback_movable_pages() & reclaim_clean_pages_from_list() to avoid isolated balloon pages being wrongly reinserted in LRU lists. [akpm@linux-foundation.org: clarify awkward comment text] Signed-off-by: Rafael Aquini <aquini@redhat.com> Reported-by: Luiz Capitulino <lcapitulino@redhat.com> Tested-by: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrew Morton
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0608f43da6 |
revert "memcg, vmscan: integrate soft reclaim tighter with zone shrinking code"
Revert commit
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Andrew Morton
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b1aff7fcf8 |
revert "vmscan, memcg: do softlimit reclaim also for targeted reclaim"
Revert commit
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Andrew Morton
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694fbc0fe7 |
revert "memcg: enhance memcg iterator to support predicates"
Revert commit
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Andrew Morton
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3120055e86 |
revert "memcg, vmscan: do not attempt soft limit reclaim if it would not scan anything"
Revert commit
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Andrew Morton
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20ba27f52e |
revert "memcg, vmscan: do not fall into reclaim-all pass too quickly"
Revert commit
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Linus Torvalds
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ac4de9543a |
Merge branch 'akpm' (patches from Andrew Morton)
Merge more patches from Andrew Morton: "The rest of MM. Plus one misc cleanup" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (35 commits) mm/Kconfig: add MMU dependency for MIGRATION. kernel: replace strict_strto*() with kstrto*() mm, thp: count thp_fault_fallback anytime thp fault fails thp: consolidate code between handle_mm_fault() and do_huge_pmd_anonymous_page() thp: do_huge_pmd_anonymous_page() cleanup thp: move maybe_pmd_mkwrite() out of mk_huge_pmd() mm: cleanup add_to_page_cache_locked() thp: account anon transparent huge pages into NR_ANON_PAGES truncate: drop 'oldsize' truncate_pagecache() parameter mm: make lru_add_drain_all() selective memcg: document cgroup dirty/writeback memory statistics memcg: add per cgroup writeback pages accounting memcg: check for proper lock held in mem_cgroup_update_page_stat memcg: remove MEMCG_NR_FILE_MAPPED memcg: reduce function dereference memcg: avoid overflow caused by PAGE_ALIGN memcg: rename RESOURCE_MAX to RES_COUNTER_MAX memcg: correct RESOURCE_MAX to ULLONG_MAX mm: memcg: do not trap chargers with full callstack on OOM mm: memcg: rework and document OOM waiting and wakeup ... |
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Andrew Morton
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f894ffa865 |
memcg: trivial cleanups
Clean up some mess made by the "Soft limit rework" series, and a few other things. Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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e975de998b |
memcg, vmscan: do not fall into reclaim-all pass too quickly
shrink_zone starts with soft reclaim pass first and then falls back to regular reclaim if nothing has been scanned. This behavior is natural but there is a catch. Memcg iterators, when used with the reclaim cookie, are designed to help to prevent from over reclaim by interleaving reclaimers (per node-zone-priority) so the tree walk might miss many (even all) nodes in the hierarchy e.g. when there are direct reclaimers racing with each other or with kswapd in the global case or multiple allocators reaching the limit for the target reclaim case. To make it even more complicated, targeted reclaim doesn't do the whole tree walk because it stops reclaiming once it reclaims sufficient pages. As a result groups over the limit might be missed, thus nothing is scanned, and reclaim would fall back to the reclaim all mode. This patch checks for the incomplete tree walk in shrink_zone. If no group has been visited and the hierarchy is soft reclaimable then we must have missed some groups, in which case the __shrink_zone is called again. This doesn't guarantee there will be some progress of course because the current reclaimer might be still racing with others but it would at least give a chance to start the walk without a big risk of reclaim latencies. Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Glauber Costa <glommer@openvz.org> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michel Lespinasse <walken@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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e839b6a1c8 |
memcg, vmscan: do not attempt soft limit reclaim if it would not scan anything
mem_cgroup_should_soft_reclaim controls whether soft reclaim pass is done and it always says yes currently. Memcg iterators are clever to skip nodes that are not soft reclaimable quite efficiently but mem_cgroup_should_soft_reclaim can be more clever and do not start the soft reclaim pass at all if it knows that nothing would be scanned anyway. In order to do that, simply reuse mem_cgroup_soft_reclaim_eligible for the target group of the reclaim and allow the pass only if the whole subtree wouldn't be skipped. Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Glauber Costa <glommer@openvz.org> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michel Lespinasse <walken@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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de57780dc6 |
memcg: enhance memcg iterator to support predicates
The caller of the iterator might know that some nodes or even subtrees should be skipped but there is no way to tell iterators about that so the only choice left is to let iterators to visit each node and do the selection outside of the iterating code. This, however, doesn't scale well with hierarchies with many groups where only few groups are interesting. This patch adds mem_cgroup_iter_cond variant of the iterator with a callback which gets called for every visited node. There are three possible ways how the callback can influence the walk. Either the node is visited, it is skipped but the tree walk continues down the tree or the whole subtree of the current group is skipped. [hughd@google.com: fix memcg-less page reclaim] Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Glauber Costa <glommer@openvz.org> Cc: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michel Lespinasse <walken@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Ying Han <yinghan@google.com> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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a5b7c87f92 |
vmscan, memcg: do softlimit reclaim also for targeted reclaim
Soft reclaim has been done only for the global reclaim (both background and direct). Since "memcg: integrate soft reclaim tighter with zone shrinking code" there is no reason for this limitation anymore as the soft limit reclaim doesn't use any special code paths and it is a part of the zone shrinking code which is used by both global and targeted reclaims. From the semantic point of view it is natural to consider soft limit before touching all groups in the hierarchy tree which is touching the hard limit because soft limit tells us where to push back when there is a memory pressure. It is not important whether the pressure comes from the limit or imbalanced zones. This patch simply enables soft reclaim unconditionally in mem_cgroup_should_soft_reclaim so it is enabled for both global and targeted reclaim paths. mem_cgroup_soft_reclaim_eligible needs to learn about the root of the reclaim to know where to stop checking soft limit state of parents up the hierarchy. Say we have A (over soft limit) \ B (below s.l., hit the hard limit) / \ C D (below s.l.) B is the source of the outside memory pressure now for D but we shouldn't soft reclaim it because it is behaving well under B subtree and we can still reclaim from C (pressumably it is over the limit). mem_cgroup_soft_reclaim_eligible should therefore stop climbing up the hierarchy at B (root of the memory pressure). Signed-off-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Glauber Costa <glommer@openvz.org> Reviewed-by: Tejun Heo <tj@kernel.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michel Lespinasse <walken@google.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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3b38722efd |
memcg, vmscan: integrate soft reclaim tighter with zone shrinking code
This patchset is sitting out of tree for quite some time without any objections. I would be really happy if it made it into 3.12. I do not want to push it too hard but I think this work is basically ready and waiting more doesn't help. The basic idea is quite simple. Pull soft reclaim into shrink_zone in the first step and get rid of the previous soft reclaim infrastructure. shrink_zone is done in two passes now. First it tries to do the soft limit reclaim and it falls back to reclaim-all mode if no group is over the limit or no pages have been scanned. The second pass happens at the same priority so the only time we waste is the memcg tree walk which has been updated in the third step to have only negligible overhead. As a bonus we will get rid of a _lot_ of code by this and soft reclaim will not stand out like before when it wasn't integrated into the zone shrinking code and it reclaimed at priority 0 (the testing results show that some workloads suffers from such an aggressive reclaim). The clean up is in a separate patch because I felt it would be easier to review that way. The second step is soft limit reclaim integration into targeted reclaim. It should be rather straight forward. Soft limit has been used only for the global reclaim so far but it makes sense for any kind of pressure coming from up-the-hierarchy, including targeted reclaim. The third step (patches 4-8) addresses the tree walk overhead by enhancing memcg iterators to enable skipping whole subtrees and tracking number of over soft limit children at each level of the hierarchy. This information is updated same way the old soft limit tree was updated (from memcg_check_events) so we shouldn't see an additional overhead. In fact mem_cgroup_update_soft_limit is much simpler than tree manipulation done previously. __shrink_zone uses mem_cgroup_soft_reclaim_eligible as a predicate for mem_cgroup_iter so the decision whether a particular group should be visited is done at the iterator level which allows us to decide to skip the whole subtree as well (if there is no child in excess). This reduces the tree walk overhead considerably. * TEST 1 ======== My primary test case was a parallel kernel build with 2 groups (make is running with -j8 with a distribution .config in a separate cgroup without any hard limit) on a 32 CPU machine booted with 1GB memory and both builds run taskset to Node 0 cpus. I was mostly interested in 2 setups. Default - no soft limit set and - and 0 soft limit set to both groups. The first one should tell us whether the rework regresses the default behavior while the second one should show us improvements in an extreme case where both workloads are always over the soft limit. /usr/bin/time -v has been used to collect the statistics and each configuration had 3 runs after fresh boot without any other load on the system. base is mmotm-2013-07-18-16-40 rework all 8 patches applied on top of base * No-limit User no-limit/base: min: 651.92 max: 672.65 avg: 664.33 std: 8.01 runs: 6 no-limit/rework: min: 657.34 [100.8%] max: 668.39 [99.4%] avg: 663.13 [99.8%] std: 3.61 runs: 6 System no-limit/base: min: 69.33 max: 71.39 avg: 70.32 std: 0.79 runs: 6 no-limit/rework: min: 69.12 [99.7%] max: 71.05 [99.5%] avg: 70.04 [99.6%] std: 0.59 runs: 6 Elapsed no-limit/base: min: 398.27 max: 422.36 avg: 408.85 std: 7.74 runs: 6 no-limit/rework: min: 386.36 [97.0%] max: 438.40 [103.8%] avg: 416.34 [101.8%] std: 18.85 runs: 6 The results are within noise. Elapsed time has a bigger variance but the average looks good. * 0-limit User 0-limit/base: min: 573.76 max: 605.63 avg: 585.73 std: 12.21 runs: 6 0-limit/rework: min: 645.77 [112.6%] max: 666.25 [110.0%] avg: 656.97 [112.2%] std: 7.77 runs: 6 System 0-limit/base: min: 69.57 max: 71.13 avg: 70.29 std: 0.54 runs: 6 0-limit/rework: min: 68.68 [98.7%] max: 71.40 [100.4%] avg: 69.91 [99.5%] std: 0.87 runs: 6 Elapsed 0-limit/base: min: 1306.14 max: 1550.17 avg: 1430.35 std: 90.86 runs: 6 0-limit/rework: min: 404.06 [30.9%] max: 465.94 [30.1%] avg: 434.81 [30.4%] std: 22.68 runs: 6 The improvement is really huge here (even bigger than with my previous testing and I suspect that this highly depends on the storage). Page fault statistics tell us at least part of the story: Minor 0-limit/base: min: 37180461.00 max: 37319986.00 avg: 37247470.00 std: 54772.71 runs: 6 0-limit/rework: min: 36751685.00 [98.8%] max: 36805379.00 [98.6%] avg: 36774506.33 [98.7%] std: 17109.03 runs: 6 Major 0-limit/base: min: 170604.00 max: 221141.00 avg: 196081.83 std: 18217.01 runs: 6 0-limit/rework: min: 2864.00 [1.7%] max: 10029.00 [4.5%] avg: 5627.33 [2.9%] std: 2252.71 runs: 6 Same as with my previous testing Minor faults are more or less within noise but Major fault count is way bellow the base kernel. While this looks as a nice win it is fair to say that 0-limit configuration is quite artificial. So I was playing with 0-no-limit loads as well. * TEST 2 ======== The following results are from 2 groups configuration on a 16GB machine (single NUMA node). - A running stream IO (dd if=/dev/zero of=local.file bs=1024) with 2*TotalMem with 0 soft limit. - B running a mem_eater which consumes TotalMem-1G without any limit. The mem_eater consumes the memory in 100 chunks with 1s nap after each mmap+poppulate so that both loads have chance to fight for the memory. The expected result is that B shouldn't be reclaimed and A shouldn't see a big dropdown in elapsed time. User base: min: 2.68 max: 2.89 avg: 2.76 std: 0.09 runs: 3 rework: min: 3.27 [122.0%] max: 3.74 [129.4%] avg: 3.44 [124.6%] std: 0.21 runs: 3 System base: min: 86.26 max: 88.29 avg: 87.28 std: 0.83 runs: 3 rework: min: 81.05 [94.0%] max: 84.96 [96.2%] avg: 83.14 [95.3%] std: 1.61 runs: 3 Elapsed base: min: 317.28 max: 332.39 avg: 325.84 std: 6.33 runs: 3 rework: min: 281.53 [88.7%] max: 298.16 [89.7%] avg: 290.99 [89.3%] std: 6.98 runs: 3 System time improved slightly as well as Elapsed. My previous testing has shown worse numbers but this again seem to depend on the storage speed. My theory is that the writeback doesn't catch up and prio-0 soft reclaim falls into wait on writeback page too often in the base kernel. The patched kernel doesn't do that because the soft reclaim is done from the kswapd/direct reclaim context. This can be seen on the following graph nicely. The A's group usage_in_bytes regurarly drops really low very often. All 3 runs http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/stream.png resp. a detail of the single run http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/stream-one-run.png mem_eater seems to be doing better as well. It gets to the full allocation size faster as can be seen on the following graph: http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/mem_eater-one-run.png /proc/meminfo collected during the test also shows that rework kernel hasn't swapped that much (well almost not at all): base: max: 123900 K avg: 56388.29 K rework: max: 300 K avg: 128.68 K kswapd and direct reclaim statistics are of no use unfortunatelly because soft reclaim is not accounted properly as the counters are hidden by global_reclaim() checks in the base kernel. * TEST 3 ======== Another test was the same configuration as TEST2 except the stream IO was replaced by a single kbuild (16 parallel jobs bound to Node0 cpus same as in TEST1) and mem_eater allocated TotalMem-200M so kbuild had only 200MB left. Kbuild did better with the rework kernel here as well: User base: min: 860.28 max: 872.86 avg: 868.03 std: 5.54 runs: 3 rework: min: 880.81 [102.4%] max: 887.45 [101.7%] avg: 883.56 [101.8%] std: 2.83 runs: 3 System base: min: 84.35 max: 85.06 avg: 84.79 std: 0.31 runs: 3 rework: min: 85.62 [101.5%] max: 86.09 [101.2%] avg: 85.79 [101.2%] std: 0.21 runs: 3 Elapsed base: min: 135.36 max: 243.30 avg: 182.47 std: 45.12 runs: 3 rework: min: 110.46 [81.6%] max: 116.20 [47.8%] avg: 114.15 [62.6%] std: 2.61 runs: 3 Minor base: min: 36635476.00 max: 36673365.00 avg: 36654812.00 std: 15478.03 runs: 3 rework: min: 36639301.00 [100.0%] max: 36695541.00 [100.1%] avg: 36665511.00 [100.0%] std: 23118.23 runs: 3 Major base: min: 14708.00 max: 53328.00 avg: 31379.00 std: 16202.24 runs: 3 rework: min: 302.00 [2.1%] max: 414.00 [0.8%] avg: 366.33 [1.2%] std: 47.22 runs: 3 Again we can see a significant improvement in Elapsed (it also seems to be more stable), there is a huge dropdown for the Major page faults and much more swapping: base: max: 583736 K avg: 112547.43 K rework: max: 4012 K avg: 124.36 K Graphs from all three runs show the variability of the kbuild quite nicely. It even seems that it took longer after every run with the base kernel which would be quite surprising as the source tree for the build is removed and caches are dropped after each run so the build operates on a freshly extracted sources everytime. http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/kbuild-mem_eater.png My other testing shows that this is just a matter of timing and other runs behave differently the std for Elapsed time is similar ~50. Example of other three runs: http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/kbuild-mem_eater2.png So to wrap this up. The series is still doing good and improves the soft limit. The testing results for bunch of cgroups with both stream IO and kbuild loads can be found in "memcg: track children in soft limit excess to improve soft limit". This patch: Memcg soft reclaim has been traditionally triggered from the global reclaim paths before calling shrink_zone. mem_cgroup_soft_limit_reclaim then picked up a group which exceeds the soft limit the most and reclaimed it with 0 priority to reclaim at least SWAP_CLUSTER_MAX pages. The infrastructure requires per-node-zone trees which hold over-limit groups and keep them up-to-date (via memcg_check_events) which is not cost free. Although this overhead hasn't turned out to be a bottle neck the implementation is suboptimal because mem_cgroup_update_tree has no idea which zones consumed memory over the limit so we could easily end up having a group on a node-zone tree having only few pages from that node-zone. This patch doesn't try to fix node-zone trees management because it seems that integrating soft reclaim into zone shrinking sounds much easier and more appropriate for several reasons. First of all 0 priority reclaim was a crude hack which might lead to big stalls if the group's LRUs are big and hard to reclaim (e.g. a lot of dirty/writeback pages). Soft reclaim should be applicable also to the targeted reclaim which is awkward right now without additional hacks. Last but not least the whole infrastructure eats quite some code. After this patch shrink_zone is done in 2 passes. First it tries to do the soft reclaim if appropriate (only for global reclaim for now to keep compatible with the original state) and fall back to ignoring soft limit if no group is eligible to soft reclaim or nothing has been scanned during the first pass. Only groups which are over their soft limit or any of their parents up the hierarchy is over the limit are considered eligible during the first pass. Soft limit tree which is not necessary anymore will be removed in the follow up patch to make this patch smaller and easier to review. Signed-off-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Glauber Costa <glommer@openvz.org> Reviewed-by: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Ying Han <yinghan@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
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26935fb06e |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs pile 4 from Al Viro: "list_lru pile, mostly" This came out of Andrew's pile, Al ended up doing the merge work so that Andrew didn't have to. Additionally, a few fixes. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (42 commits) super: fix for destroy lrus list_lru: dynamically adjust node arrays shrinker: Kill old ->shrink API. shrinker: convert remaining shrinkers to count/scan API staging/lustre/libcfs: cleanup linux-mem.h staging/lustre/ptlrpc: convert to new shrinker API staging/lustre/obdclass: convert lu_object shrinker to count/scan API staging/lustre/ldlm: convert to shrinkers to count/scan API hugepage: convert huge zero page shrinker to new shrinker API i915: bail out earlier when shrinker cannot acquire mutex drivers: convert shrinkers to new count/scan API fs: convert fs shrinkers to new scan/count API xfs: fix dquot isolation hang xfs-convert-dquot-cache-lru-to-list_lru-fix xfs: convert dquot cache lru to list_lru xfs: rework buffer dispose list tracking xfs-convert-buftarg-lru-to-generic-code-fix xfs: convert buftarg LRU to generic code fs: convert inode and dentry shrinking to be node aware vmscan: per-node deferred work ... |
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Lisa Du
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6e543d5780 |
mm: vmscan: fix do_try_to_free_pages() livelock
This patch is based on KOSAKI's work and I add a little more description, please refer https://lkml.org/lkml/2012/6/14/74. Currently, I found system can enter a state that there are lots of free pages in a zone but only order-0 and order-1 pages which means the zone is heavily fragmented, then high order allocation could make direct reclaim path's long stall(ex, 60 seconds) especially in no swap and no compaciton enviroment. This problem happened on v3.4, but it seems issue still lives in current tree, the reason is do_try_to_free_pages enter live lock: kswapd will go to sleep if the zones have been fully scanned and are still not balanced. As kswapd thinks there's little point trying all over again to avoid infinite loop. Instead it changes order from high-order to 0-order because kswapd think order-0 is the most important. Look at |
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Vlastimil Babka
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0ec3b74c7f |
mm: putback_lru_page: remove unnecessary call to page_lru_base_type()
The goal of this patch series is to improve performance of munlock() of
large mlocked memory areas on systems without THP. This is motivated by
reported very long times of crash recovery of processes with such areas,
where munlock() can take several seconds. See
http://lwn.net/Articles/548108/
The work was driven by a simple benchmark (to be included in mmtests) that
mmaps() e.g. 56GB with MAP_LOCKED | MAP_POPULATE and measures the time of
munlock(). Profiling was performed by attaching operf --pid to the
process and sending a signal to trigger the munlock() part and then notify
bach the monitoring wrapper to stop operf, so that only munlock() appears
in the profile.
The profiles have shown that CPU time is spent mostly by atomic operations
and repeated locking per single pages. This series aims to reduce both, starting
from simpler to more complex changes.
Patch 1 performs a simple cleanup in putback_lru_page() so that page lru base
type is not determined without being actually needed.
Patch 2 removes an unnecessary call to lru_add_drain() which drains the per-cpu
pagevec after each munlocked page is put there.
Patch 3 changes munlock_vma_range() to use an on-stack pagevec for isolating
multiple non-THP pages under a single lru_lock instead of locking and
processing each page separately.
Patch 4 changes the NR_MLOCK accounting to be called only once per the pvec
introduced by previous patch.
Patch 5 uses the introduced pagevec to batch also the work of putback_lru_page
when possible, bypassing the per-cpu pvec and associated overhead.
Patch 6 removes a redundant get_page/put_page pair which saves costly atomic
operations.
Patch 7 avoids calling follow_page_mask() on each individual page, and obtains
multiple page references under a single page table lock where possible.
Measurements were made using 3.11-rc3 as a baseline. The first set of
measurements shows the possibly ideal conditions where batching should
help the most. All memory is allocated from a single NUMA node and THP is
disabled.
timedmunlock
3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3
0 1 2 3 4 5 6 7
Elapsed min 3.38 ( 0.00%) 3.39 ( -0.13%) 3.00 ( 11.33%) 2.70 ( 20.20%) 2.67 ( 21.11%) 2.37 ( 29.88%) 2.20 ( 34.91%) 1.91 ( 43.59%)
Elapsed mean 3.39 ( 0.00%) 3.40 ( -0.23%) 3.01 ( 11.33%) 2.70 ( 20.26%) 2.67 ( 21.21%) 2.38 ( 29.88%) 2.21 ( 34.93%) 1.92 ( 43.46%)
Elapsed stddev 0.01 ( 0.00%) 0.01 (-43.09%) 0.01 ( 15.42%) 0.01 ( 23.42%) 0.00 ( 89.78%) 0.01 ( -7.15%) 0.00 ( 76.69%) 0.02 (-91.77%)
Elapsed max 3.41 ( 0.00%) 3.43 ( -0.52%) 3.03 ( 11.29%) 2.72 ( 20.16%) 2.67 ( 21.63%) 2.40 ( 29.50%) 2.21 ( 35.21%) 1.96 ( 42.39%)
Elapsed range 0.03 ( 0.00%) 0.04 (-51.16%) 0.02 ( 6.27%) 0.02 ( 14.67%) 0.00 ( 88.90%) 0.03 (-19.18%) 0.01 ( 73.70%) 0.06 (-113.35%
The second set of measurements simulates the worst possible conditions for
batching by using numactl --interleave, so that there is in fact only one
page per pagevec. Even in this case the series seems to improve
performance thanks to reduced atomic operations and removal of
lru_add_drain().
timedmunlock
3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3
0 1 2 3 4 5 6 7
Elapsed min 4.00 ( 0.00%) 4.04 ( -0.93%) 3.87 ( 3.37%) 3.72 ( 6.94%) 3.81 ( 4.72%) 3.69 ( 7.82%) 3.64 ( 8.92%) 3.41 ( 14.81%)
Elapsed mean 4.17 ( 0.00%) 4.15 ( 0.51%) 4.03 ( 3.49%) 3.89 ( 6.84%) 3.86 ( 7.48%) 3.89 ( 6.69%) 3.70 ( 11.27%) 3.48 ( 16.59%)
Elapsed stddev 0.16 ( 0.00%) 0.08 ( 50.76%) 0.10 ( 41.58%) 0.16 ( 4.59%) 0.05 ( 72.38%) 0.19 (-12.91%) 0.05 ( 68.09%) 0.06 ( 66.03%)
Elapsed max 4.34 ( 0.00%) 4.32 ( 0.56%) 4.19 ( 3.62%) 4.12 ( 5.15%) 3.91 ( 9.88%) 4.12 ( 5.25%) 3.80 ( 12.58%) 3.56 ( 18.08%)
Elapsed range 0.34 ( 0.00%) 0.28 ( 17.91%) 0.32 ( 6.45%) 0.40 (-15.73%) 0.10 ( 70.06%) 0.43 (-24.84%) 0.15 ( 55.32%) 0.15 ( 56.16%)
For completeness, a third set of measurements shows the situation where
THP is enabled and allocations are again done on a single NUMA node. Here
munlock() is already very fast thanks to huge pages, and this series does
not compromise that performance. It seems that the removal of call to
lru_add_drain() still helps a bit.
timedmunlock
3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3 3.11-rc3
0 1 2 3 4 5 6 7
Elapsed min 0.01 ( 0.00%) 0.01 ( -0.11%) 0.01 ( 6.59%) 0.01 ( 5.41%) 0.01 ( 5.45%) 0.01 ( 5.03%) 0.01 ( 6.08%) 0.01 ( 5.20%)
Elapsed mean 0.01 ( 0.00%) 0.01 ( -0.27%) 0.01 ( 6.39%) 0.01 ( 5.30%) 0.01 ( 5.32%) 0.01 ( 5.03%) 0.01 ( 5.97%) 0.01 ( 5.22%)
Elapsed stddev 0.00 ( 0.00%) 0.00 ( -9.59%) 0.00 ( 10.77%) 0.00 ( 3.24%) 0.00 ( 24.42%) 0.00 ( 31.86%) 0.00 ( -7.46%) 0.00 ( 6.11%)
Elapsed max 0.01 ( 0.00%) 0.01 ( -0.01%) 0.01 ( 6.83%) 0.01 ( 5.42%) 0.01 ( 5.79%) 0.01 ( 5.53%) 0.01 ( 6.08%) 0.01 ( 5.26%)
Elapsed range 0.00 ( 0.00%) 0.00 ( 7.30%) 0.00 ( 24.38%) 0.00 ( 6.10%) 0.00 ( 30.79%) 0.00 ( 42.52%) 0.00 ( 6.11%) 0.00 ( 10.07%)
This patch (of 7):
In putback_lru_page() since commit
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Johannes Weiner
|
892f795df1 |
mm: vmscan: fix numa reclaim balance problem in kswapd
The way the page allocator interacts with kswapd creates aging imbalances, where the amount of time a userspace page gets in memory under reclaim pressure is dependent on which zone, which node the allocator took the page frame from. #1 fixes missed kswapd wakeups on NUMA systems, which lead to some nodes falling behind for a full reclaim cycle relative to the other nodes in the system #3 fixes an interaction where kswapd and a continuous stream of page allocations keep the preferred zone of a task between the high and low watermark (allocations succeed + kswapd does not go to sleep) indefinitely, completely underutilizing the lower zones and thrashing on the preferred zone These patches are the aging fairness part of the thrash-detection based file LRU balancing. Andrea recommended to submit them separately as they are bugfixes in their own right. The following test ran a foreground workload (memcachetest) with background IO of various sizes on a 4 node 8G system (similar results were observed with single-node 4G systems): parallelio BAS FAIRALLO BASE FAIRALLOC Ops memcachetest-0M 5170.00 ( 0.00%) 5283.00 ( 2.19%) Ops memcachetest-791M 4740.00 ( 0.00%) 5293.00 ( 11.67%) Ops memcachetest-2639M 2551.00 ( 0.00%) 4950.00 ( 94.04%) Ops memcachetest-4487M 2606.00 ( 0.00%) 3922.00 ( 50.50%) Ops io-duration-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops io-duration-791M 55.00 ( 0.00%) 18.00 ( 67.27%) Ops io-duration-2639M 235.00 ( 0.00%) 103.00 ( 56.17%) Ops io-duration-4487M 278.00 ( 0.00%) 173.00 ( 37.77%) Ops swaptotal-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swaptotal-791M 245184.00 ( 0.00%) 0.00 ( 0.00%) Ops swaptotal-2639M 468069.00 ( 0.00%) 108778.00 ( 76.76%) Ops swaptotal-4487M 452529.00 ( 0.00%) 76623.00 ( 83.07%) Ops swapin-0M 0.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-791M 108297.00 ( 0.00%) 0.00 ( 0.00%) Ops swapin-2639M 169537.00 ( 0.00%) 50031.00 ( 70.49%) Ops swapin-4487M 167435.00 ( 0.00%) 34178.00 ( 79.59%) Ops minorfaults-0M 1518666.00 ( 0.00%) 1503993.00 ( 0.97%) Ops minorfaults-791M 1676963.00 ( 0.00%) 1520115.00 ( 9.35%) Ops minorfaults-2639M 1606035.00 ( 0.00%) 1799717.00 (-12.06%) Ops minorfaults-4487M 1612118.00 ( 0.00%) 1583825.00 ( 1.76%) Ops majorfaults-0M 6.00 ( 0.00%) 0.00 ( 0.00%) Ops majorfaults-791M 13836.00 ( 0.00%) 10.00 ( 99.93%) Ops majorfaults-2639M 22307.00 ( 0.00%) 6490.00 ( 70.91%) Ops majorfaults-4487M 21631.00 ( 0.00%) 4380.00 ( 79.75%) BAS FAIRALLO BASE FAIRALLOC User 287.78 460.97 System 2151.67 3142.51 Elapsed 9737.00 8879.34 BAS FAIRALLO BASE FAIRALLOC Minor Faults 53721925 57188551 Major Faults 392195 15157 Swap Ins 2994854 112770 Swap Outs 4907092 134982 Direct pages scanned 0 41824 Kswapd pages scanned 32975063 8128269 Kswapd pages reclaimed 6323069 7093495 Direct pages reclaimed 0 41824 Kswapd efficiency 19% 87% Kswapd velocity 3386.573 915.414 Direct efficiency 100% 100% Direct velocity 0.000 4.710 Percentage direct scans 0% 0% Zone normal velocity 2011.338 550.661 Zone dma32 velocity 1365.623 369.221 Zone dma velocity 9.612 0.242 Page writes by reclaim 18732404.000 614807.000 Page writes file 13825312 479825 Page writes anon 4907092 134982 Page reclaim immediate 85490 5647 Sector Reads 12080532 483244 Sector Writes 88740508 65438876 Page rescued immediate 0 0 Slabs scanned 82560 12160 Direct inode steals 0 0 Kswapd inode steals 24401 40013 Kswapd skipped wait 0 0 THP fault alloc 6 8 THP collapse alloc 5481 5812 THP splits 75 22 THP fault fallback 0 0 THP collapse fail 0 0 Compaction stalls 0 54 Compaction success 0 45 Compaction failures 0 9 Page migrate success 881492 82278 Page migrate failure 0 0 Compaction pages isolated 0 60334 Compaction migrate scanned 0 53505 Compaction free scanned 0 1537605 Compaction cost 914 86 NUMA PTE updates 46738231 41988419 NUMA hint faults 31175564 24213387 NUMA hint local faults 10427393 6411593 NUMA pages migrated 881492 55344 AutoNUMA cost 156221 121361 The overall runtime was reduced, throughput for both the foreground workload as well as the background IO improved, major faults, swapping and reclaim activity shrunk significantly, reclaim efficiency more than quadrupled. This patch: When the page allocator fails to get a page from all zones in its given zonelist, it wakes up the per-node kswapds for all zones that are at their low watermark. However, with a system under load the free pages in a zone can fluctuate enough that the allocation fails but the kswapd wakeup is also skipped while the zone is still really close to the low watermark. When one node misses a wakeup like this, it won't be aged before all the other node's zones are down to their low watermarks again. And skipping a full aging cycle is an obvious fairness problem. Kswapd runs until the high watermarks are restored, so it should also be woken when the high watermarks are not met. This ages nodes more equally and creates a safety margin for the page counter fluctuation. By using zone_balanced(), it will now check, in addition to the watermark, if compaction requires more order-0 pages to create a higher order page. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Paul Bolle <paul.bollee@gmail.com> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Dave Chinner
|
a0b02131c5 |
shrinker: Kill old ->shrink API.
There are no more users of this API, so kill it dead, dead, dead and quietly bury the corpse in a shallow, unmarked grave in a dark forest deep in the hills... [glommer@openvz.org: added flowers to the grave] Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Glauber Costa <glommer@openvz.org> Reviewed-by: Greg Thelen <gthelen@google.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Arve Hjønnevåg <arve@android.com> Cc: Carlos Maiolino <cmaiolino@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Rientjes <rientjes@google.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: J. Bruce Fields <bfields@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Kent Overstreet <koverstreet@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Thomas Hellstrom <thellstrom@vmware.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
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Glauber Costa
|
1d3d4437ea |
vmscan: per-node deferred work
The list_lru infrastructure already keeps per-node LRU lists in its node-specific list_lru_node arrays and provide us with a per-node API, and the shrinkers are properly equiped with node information. This means that we can now focus our shrinking effort in a single node, but the work that is deferred from one run to another is kept global at nr_in_batch. Work can be deferred, for instance, during direct reclaim under a GFP_NOFS allocation, where situation, all the filesystem shrinkers will be prevented from running and accumulate in nr_in_batch the amount of work they should have done, but could not. This creates an impedance problem, where upon node pressure, work deferred will accumulate and end up being flushed in other nodes. The problem we describe is particularly harmful in big machines, where many nodes can accumulate at the same time, all adding to the global counter nr_in_batch. As we accumulate more and more, we start to ask for the caches to flush even bigger numbers. The result is that the caches are depleted and do not stabilize. To achieve stable steady state behavior, we need to tackle it differently. In this patch we keep the deferred count per-node, in the new array nr_deferred[] (the name is also a bit more descriptive) and will never accumulate that to other nodes. Signed-off-by: Glauber Costa <glommer@openvz.org> Cc: Dave Chinner <dchinner@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Arve Hjønnevåg <arve@android.com> Cc: Carlos Maiolino <cmaiolino@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Rientjes <rientjes@google.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: J. Bruce Fields <bfields@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Kent Overstreet <koverstreet@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Thomas Hellstrom <thellstrom@vmware.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
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Dave Chinner
|
0ce3d74450 |
shrinker: add node awareness
Pass the node of the current zone being reclaimed to shrink_slab(), allowing the shrinker control nodemask to be set appropriately for node aware shrinkers. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Glauber Costa <glommer@openvz.org> Acked-by: Mel Gorman <mgorman@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Arve Hjønnevåg <arve@android.com> Cc: Carlos Maiolino <cmaiolino@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Rientjes <rientjes@google.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: J. Bruce Fields <bfields@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Kent Overstreet <koverstreet@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Thomas Hellstrom <thellstrom@vmware.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
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Dave Chinner
|
24f7c6b981 |
mm: new shrinker API
The current shrinker callout API uses an a single shrinker call for multiple functions. To determine the function, a special magical value is passed in a parameter to change the behaviour. This complicates the implementation and return value specification for the different behaviours. Separate the two different behaviours into separate operations, one to return a count of freeable objects in the cache, and another to scan a certain number of objects in the cache for freeing. In defining these new operations, ensure the return values and resultant behaviours are clearly defined and documented. Modify shrink_slab() to use the new API and implement the callouts for all the existing shrinkers. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Arve Hjønnevåg <arve@android.com> Cc: Carlos Maiolino <cmaiolino@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Rientjes <rientjes@google.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: J. Bruce Fields <bfields@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Kent Overstreet <koverstreet@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Thomas Hellstrom <thellstrom@vmware.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
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Mel Gorman
|
918fc718c5 |
mm: vmscan: do not scale writeback pages when deciding whether to set ZONE_WRITEBACK
After the patch "mm: vmscan: Flatten kswapd priority loop" was merged the scanning priority of kswapd changed. The priority now rises until it is scanning enough pages to meet the high watermark. shrink_inactive_list sets ZONE_WRITEBACK if a number of pages were encountered under writeback but this value is scaled based on the priority. As kswapd frequently scans with a higher priority now it is relatively easy to set ZONE_WRITEBACK. This patch removes the scaling and treates writeback pages similar to how it treats unqueued dirty pages and congested pages. The user-visible effect should be that kswapd will writeback fewer pages from reclaim context. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
5a1c9cbc15 |
mm: vmscan: do not continue scanning if reclaim was aborted for compaction
Direct reclaim is not aborting to allow compaction to go ahead properly. do_try_to_free_pages is told to abort reclaim which is happily ignores and instead increases priority instead until it reaches 0 and starts shrinking file/anon equally. This patch corrects the situation by aborting reclaim when requested instead of raising priority. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
c53954a092 |
mm: remove lru parameter from __lru_cache_add and lru_cache_add_lru
Similar to __pagevec_lru_add, this patch removes the LRU parameter from __lru_cache_add and lru_cache_add_lru as the caller does not control the exact LRU the page gets added to. lru_cache_add_lru gets renamed to lru_cache_add the name is silly without the lru parameter. With the parameter removed, it is required that the caller indicate if they want the page added to the active or inactive list by setting or clearing PageActive respectively. [akpm@linux-foundation.org: Suggested the patch] [gang.chen@asianux.com: fix used-unintialized warning] Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Chen Gang <gang.chen@asianux.com> Cc: Jan Kara <jack@suse.cz> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Alexey Lyahkov <alexey.lyashkov@gmail.com> Cc: Andrew Perepechko <anserper@ya.ru> Cc: Robin Dong <sanbai@taobao.com> Cc: Theodore Tso <tytso@mit.edu> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Bernd Schubert <bernd.schubert@fastmail.fm> Cc: David Howells <dhowells@redhat.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
b45972265f |
mm: vmscan: take page buffers dirty and locked state into account
Page reclaim keeps track of dirty and under writeback pages and uses it to determine if wait_iff_congested() should stall or if kswapd should begin writing back pages. This fails to account for buffer pages that can be under writeback but not PageWriteback which is the case for filesystems like ext3 ordered mode. Furthermore, PageDirty buffer pages can have all the buffers clean and writepage does no IO so it should not be accounted as congested. This patch adds an address_space operation that filesystems may optionally use to check if a page is really dirty or really under writeback. An implementation is provided for for buffer_heads is added and used for block operations and ext3 in ordered mode. By default the page flags are obeyed. Credit goes to Jan Kara for identifying that the page flags alone are not sufficient for ext3 and sanity checking a number of ideas on how the problem could be addressed. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
d04e8acd03 |
mm: vmscan: treat pages marked for immediate reclaim as zone congestion
Currently a zone will only be marked congested if the underlying BDI is congested but if dirty pages are spread across zones it is possible that an individual zone is full of dirty pages without being congested. The impact is that zone gets scanned very quickly potentially reclaiming really clean pages. This patch treats pages marked for immediate reclaim as congested for the purposes of marking a zone ZONE_CONGESTED and stalling in wait_iff_congested. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
8e95028280 |
mm: vmscan: move direct reclaim wait_iff_congested into shrink_list
shrink_inactive_list makes decisions on whether to stall based on the number of dirty pages encountered. The wait_iff_congested() call in shrink_page_list does no such thing and it's arbitrary. This patch moves the decision on whether to set ZONE_CONGESTED and the wait_iff_congested call into shrink_page_list. This keeps all the decisions on whether to stall or not in the one place. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
f7ab8db791 |
mm: vmscan: set zone flags before blocking
In shrink_page_list a decision may be made to stall and flag a zone as ZONE_WRITEBACK so that if a large number of unqueued dirty pages are encountered later then the reclaimer will stall. Set ZONE_WRITEBACK before potentially going to sleep so it is noticed sooner. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
b1a6f21e3b |
mm: vmscan: stall page reclaim after a list of pages have been processed
Commit "mm: vmscan: Block kswapd if it is encountering pages under writeback" blocks page reclaim if it encounters pages under writeback marked for immediate reclaim. It blocks while pages are still isolated from the LRU which is unnecessary. This patch defers the blocking until after the isolated pages have been processed and tidies up some of the comments. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
e2be15f6c3 |
mm: vmscan: stall page reclaim and writeback pages based on dirty/writepage pages encountered
Further testing of the "Reduce system disruption due to kswapd"
discovered a few problems. First and foremost, it's possible for pages
under writeback to be freed which will lead to badness. Second, as
pages were not being swapped the file LRU was being scanned faster and
clean file pages were being reclaimed. In some cases this results in
increased read IO to re-read data from disk. Third, more pages were
being written from kswapd context which can adversly affect IO
performance. Lastly, it was observed that PageDirty pages are not
necessarily dirty on all filesystems (buffers can be clean while
PageDirty is set and ->writepage generates no IO) and not all
filesystems set PageWriteback when the page is being written (e.g.
ext3). This disconnect confuses the reclaim stalling logic. This
follow-up series is aimed at these problems.
The tests were based on three kernels
vanilla: kernel 3.9 as that is what the current mmotm uses as a baseline
mmotm-20130522 is mmotm as of 22nd May with "Reduce system disruption due to
kswapd" applied on top as per what should be in Andrew's tree
right now
lessdisrupt-v7r10 is this follow-up series on top of the mmotm kernel
The first test used memcached+memcachetest while some background IO was
in progress as implemented by the parallel IO tests implement in MM
Tests. memcachetest benchmarks how many operations/second memcached can
service. It starts with no background IO on a freshly created ext4
filesystem and then re-runs the test with larger amounts of IO in the
background to roughly simulate a large copy in progress. The
expectation is that the IO should have little or no impact on
memcachetest which is running entirely in memory.
parallelio
3.9.0 3.9.0 3.9.0
vanilla mm1-mmotm-20130522 mm1-lessdisrupt-v7r10
Ops memcachetest-0M 23117.00 ( 0.00%) 22780.00 ( -1.46%) 22763.00 ( -1.53%)
Ops memcachetest-715M 23774.00 ( 0.00%) 23299.00 ( -2.00%) 22934.00 ( -3.53%)
Ops memcachetest-2385M 4208.00 ( 0.00%) 24154.00 (474.00%) 23765.00 (464.76%)
Ops memcachetest-4055M 4104.00 ( 0.00%) 25130.00 (512.33%) 24614.00 (499.76%)
Ops io-duration-0M 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops io-duration-715M 12.00 ( 0.00%) 7.00 ( 41.67%) 6.00 ( 50.00%)
Ops io-duration-2385M 116.00 ( 0.00%) 21.00 ( 81.90%) 21.00 ( 81.90%)
Ops io-duration-4055M 160.00 ( 0.00%) 36.00 ( 77.50%) 35.00 ( 78.12%)
Ops swaptotal-0M 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops swaptotal-715M 140138.00 ( 0.00%) 18.00 ( 99.99%) 18.00 ( 99.99%)
Ops swaptotal-2385M 385682.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops swaptotal-4055M 418029.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops swapin-0M 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops swapin-715M 144.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops swapin-2385M 134227.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops swapin-4055M 125618.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops minorfaults-0M 1536429.00 ( 0.00%) 1531632.00 ( 0.31%) 1533541.00 ( 0.19%)
Ops minorfaults-715M 1786996.00 ( 0.00%) 1612148.00 ( 9.78%) 1608832.00 ( 9.97%)
Ops minorfaults-2385M 1757952.00 ( 0.00%) 1614874.00 ( 8.14%) 1613541.00 ( 8.21%)
Ops minorfaults-4055M 1774460.00 ( 0.00%) 1633400.00 ( 7.95%) 1630881.00 ( 8.09%)
Ops majorfaults-0M 1.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops majorfaults-715M 184.00 ( 0.00%) 167.00 ( 9.24%) 166.00 ( 9.78%)
Ops majorfaults-2385M 24444.00 ( 0.00%) 155.00 ( 99.37%) 93.00 ( 99.62%)
Ops majorfaults-4055M 21357.00 ( 0.00%) 147.00 ( 99.31%) 134.00 ( 99.37%)
memcachetest is the transactions/second reported by memcachetest. In
the vanilla kernel note that performance drops from around
23K/sec to just over 4K/second when there is 2385M of IO going
on in the background. With current mmotm, there is no collapse
in performance and with this follow-up series there is little
change.
swaptotal is the total amount of swap traffic. With mmotm and the follow-up
series, the total amount of swapping is much reduced.
3.9.0 3.9.0 3.9.0
vanillamm1-mmotm-20130522mm1-lessdisrupt-v7r10
Minor Faults 11160152 10706748 10622316
Major Faults 46305 755 678
Swap Ins 260249 0 0
Swap Outs 683860 18 18
Direct pages scanned 0 678 2520
Kswapd pages scanned 6046108 8814900 1639279
Kswapd pages reclaimed 1081954
|
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Mel Gorman
|
7c954f6de6 |
mm: vmscan: move logic from balance_pgdat() to kswapd_shrink_zone()
balance_pgdat() is very long and some of the logic can and should be internal to kswapd_shrink_zone(). Move it so the flow of balance_pgdat() is marginally easier to follow. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
b7ea3c417b |
mm: vmscan: check if kswapd should writepage once per pgdat scan
Currently kswapd checks if it should start writepage as it shrinks each zone without taking into consideration if the zone is balanced or not. This is not wrong as such but it does not make much sense either. This patch checks once per pgdat scan if kswapd should be writing pages. Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
283aba9f9e |
mm: vmscan: block kswapd if it is encountering pages under writeback
Historically, kswapd used to congestion_wait() at higher priorities if
it was not making forward progress. This made no sense as the failure
to make progress could be completely independent of IO. It was later
replaced by wait_iff_congested() and removed entirely by commit
|
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Mel Gorman
|
d43006d503 |
mm: vmscan: have kswapd writeback pages based on dirty pages encountered, not priority
Currently kswapd queues dirty pages for writeback if scanning at an elevated priority but the priority kswapd scans at is not related to the number of unqueued dirty encountered. Since commit "mm: vmscan: Flatten kswapd priority loop", the priority is related to the size of the LRU and the zone watermark which is no indication as to whether kswapd should write pages or not. This patch tracks if an excessive number of unqueued dirty pages are being encountered at the end of the LRU. If so, it indicates that dirty pages are being recycled before flusher threads can clean them and flags the zone so that kswapd will start writing pages until the zone is balanced. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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|
Mel Gorman
|
9aa41348a8 |
mm: vmscan: do not allow kswapd to scan at maximum priority
Page reclaim at priority 0 will scan the entire LRU as priority 0 is considered to be a near OOM condition. Kswapd can reach priority 0 quite easily if it is encountering a large number of pages it cannot reclaim such as pages under writeback. When this happens, kswapd reclaims very aggressively even though there may be no real risk of allocation failure or OOM. This patch prevents kswapd reaching priority 0 and trying to reclaim the world. Direct reclaimers will still reach priority 0 in the event of an OOM situation. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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|
Mel Gorman
|
2ab44f4345 |
mm: vmscan: decide whether to compact the pgdat based on reclaim progress
In the past, kswapd makes a decision on whether to compact memory after the pgdat was considered balanced. This more or less worked but it is late to make such a decision and does not fit well now that kswapd makes a decision whether to exit the zone scanning loop depending on reclaim progress. This patch will compact a pgdat if at least the requested number of pages were reclaimed from unbalanced zones for a given priority. If any zone is currently balanced, kswapd will not call compaction as it is expected the necessary pages are already available. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
b8e83b942a |
mm: vmscan: flatten kswapd priority loop
kswapd stops raising the scanning priority when at least SWAP_CLUSTER_MAX pages have been reclaimed or the pgdat is considered balanced. It then rechecks if it needs to restart at DEF_PRIORITY and whether high-order reclaim needs to be reset. This is not wrong per-se but it is confusing to follow and forcing kswapd to stay at DEF_PRIORITY may require several restarts before it has scanned enough pages to meet the high watermark even at 100% efficiency. This patch irons out the logic a bit by controlling when priority is raised and removing the "goto loop_again". This patch has kswapd raise the scanning priority until it is scanning enough pages that it could meet the high watermark in one shrink of the LRU lists if it is able to reclaim at 100% efficiency. It will not raise the scanning prioirty higher unless it is failing to reclaim any pages. To avoid infinite looping for high-order allocation requests kswapd will not reclaim for high-order allocations when it has reclaimed at least twice the number of pages as the allocation request. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
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Mel Gorman
|
e82e0561da |
mm: vmscan: obey proportional scanning requirements for kswapd
Simplistically, the anon and file LRU lists are scanned proportionally depending on the value of vm.swappiness although there are other factors taken into account by get_scan_count(). The patch "mm: vmscan: Limit the number of pages kswapd reclaims" limits the number of pages kswapd reclaims but it breaks this proportional scanning and may evenly shrink anon/file LRUs regardless of vm.swappiness. This patch preserves the proportional scanning and reclaim. It does mean that kswapd will reclaim more than requested but the number of pages will be related to the high watermark. [mhocko@suse.cz: Correct proportional reclaim for memcg and simplify] [kamezawa.hiroyu@jp.fujitsu.com: Recalculate scan based on target] [hannes@cmpxchg.org: Account for already scanned pages properly] Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
75485363ce |
mm: vmscan: limit the number of pages kswapd reclaims at each priority
This series does not fix all the current known problems with reclaim but
it addresses one important swapping bug when there is background IO.
Changelog since V3
- Drop the slab shrink changes in light of Glaubers series and
discussions highlighted that there were a number of potential
problems with the patch. (mel)
- Rebased to 3.10-rc1
Changelog since V2
- Preserve ratio properly for proportional scanning (kamezawa)
Changelog since V1
- Rename ZONE_DIRTY to ZONE_TAIL_LRU_DIRTY (andi)
- Reformat comment in shrink_page_list (andi)
- Clarify some comments (dhillf)
- Rework how the proportional scanning is preserved
- Add PageReclaim check before kswapd starts writeback
- Reset sc.nr_reclaimed on every full zone scan
Kswapd and page reclaim behaviour has been screwy in one way or the
other for a long time. Very broadly speaking it worked in the far past
because machines were limited in memory so it did not have that many
pages to scan and it stalled congestion_wait() frequently to prevent it
going completely nuts. In recent times it has behaved very
unsatisfactorily with some of the problems compounded by the removal of
stall logic and the introduction of transparent hugepage support with
high-order reclaims.
There are many variations of bugs that are rooted in this area. One
example is reports of a large copy operations or backup causing the
machine to grind to a halt or applications pushed to swap. Sometimes in
low memory situations a large percentage of memory suddenly gets
reclaimed. In other cases an application starts and kswapd hits 100%
CPU usage for prolonged periods of time and so on. There is now talk of
introducing features like an extra free kbytes tunable to work around
aspects of the problem instead of trying to deal with it. It's
compounded by the problem that it can be very workload and machine
specific.
This series aims at addressing some of the worst of these problems
without attempting to fundmentally alter how page reclaim works.
Patches 1-2 limits the number of pages kswapd reclaims while still obeying
the anon/file proportion of the LRUs it should be scanning.
Patches 3-4 control how and when kswapd raises its scanning priority and
deletes the scanning restart logic which is tricky to follow.
Patch 5 notes that it is too easy for kswapd to reach priority 0 when
scanning and then reclaim the world. Down with that sort of thing.
Patch 6 notes that kswapd starts writeback based on scanning priority which
is not necessarily related to dirty pages. It will have kswapd
writeback pages if a number of unqueued dirty pages have been
recently encountered at the tail of the LRU.
Patch 7 notes that sometimes kswapd should stall waiting on IO to complete
to reduce LRU churn and the likelihood that it'll reclaim young
clean pages or push applications to swap. It will cause kswapd
to block on IO if it detects that pages being reclaimed under
writeback are recycling through the LRU before the IO completes.
Patchies 8-9 are cosmetic but balance_pgdat() is easier to follow after they
are applied.
This was tested using memcached+memcachetest while some background IO
was in progress as implemented by the parallel IO tests implement in MM
Tests.
memcachetest benchmarks how many operations/second memcached can service
and it is run multiple times. It starts with no background IO and then
re-runs the test with larger amounts of IO in the background to roughly
simulate a large copy in progress. The expectation is that the IO
should have little or no impact on memcachetest which is running
entirely in memory.
3.10.0-rc1 3.10.0-rc1
vanilla lessdisrupt-v4
Ops memcachetest-0M 22155.00 ( 0.00%) 22180.00 ( 0.11%)
Ops memcachetest-715M 22720.00 ( 0.00%) 22355.00 ( -1.61%)
Ops memcachetest-2385M 3939.00 ( 0.00%) 23450.00 (495.33%)
Ops memcachetest-4055M 3628.00 ( 0.00%) 24341.00 (570.92%)
Ops io-duration-0M 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops io-duration-715M 12.00 ( 0.00%) 7.00 ( 41.67%)
Ops io-duration-2385M 118.00 ( 0.00%) 21.00 ( 82.20%)
Ops io-duration-4055M 162.00 ( 0.00%) 36.00 ( 77.78%)
Ops swaptotal-0M 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops swaptotal-715M 140134.00 ( 0.00%) 18.00 ( 99.99%)
Ops swaptotal-2385M 392438.00 ( 0.00%) 0.00 ( 0.00%)
Ops swaptotal-4055M 449037.00 ( 0.00%) 27864.00 ( 93.79%)
Ops swapin-0M 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops swapin-715M 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops swapin-2385M 148031.00 ( 0.00%) 0.00 ( 0.00%)
Ops swapin-4055M 135109.00 ( 0.00%) 0.00 ( 0.00%)
Ops minorfaults-0M 1529984.00 ( 0.00%) 1530235.00 ( -0.02%)
Ops minorfaults-715M 1794168.00 ( 0.00%) 1613750.00 ( 10.06%)
Ops minorfaults-2385M 1739813.00 ( 0.00%) 1609396.00 ( 7.50%)
Ops minorfaults-4055M 1754460.00 ( 0.00%) 1614810.00 ( 7.96%)
Ops majorfaults-0M 0.00 ( 0.00%) 0.00 ( 0.00%)
Ops majorfaults-715M 185.00 ( 0.00%) 180.00 ( 2.70%)
Ops majorfaults-2385M 24472.00 ( 0.00%) 101.00 ( 99.59%)
Ops majorfaults-4055M 22302.00 ( 0.00%) 229.00 ( 98.97%)
Note how the vanilla kernels performance collapses when there is enough
IO taking place in the background. This drop in performance is part of
what users complain of when they start backups. Note how the swapin and
major fault figures indicate that processes were being pushed to swap
prematurely. With the series applied, there is no noticable performance
drop and while there is still some swap activity, it's tiny.
20 iterations of this test were run in total and averaged. Every 5
iterations, additional IO was generated in the background using dd to
measure how the workload was impacted. The 0M, 715M, 2385M and 4055M
subblock refer to the amount of IO going on in the background at each
iteration. So memcachetest-2385M is reporting how many
transactions/second memcachetest recorded on average over 5 iterations
while there was 2385M of IO going on in the ground. There are six
blocks of information reported here
memcachetest is the transactions/second reported by memcachetest. In
the vanilla kernel note that performance drops from around
22K/sec to just under 4K/second when there is 2385M of IO going
on in the background. This is one type of performance collapse
users complain about if a large cp or backup starts in the
background
io-duration refers to how long it takes for the background IO to
complete. It's showing that with the patched kernel that the IO
completes faster while not interfering with the memcache
workload
swaptotal is the total amount of swap traffic. With the patched kernel,
the total amount of swapping is much reduced although it is
still not zero.
swapin in this case is an indication as to whether we are swap trashing.
The closer the swapin/swapout ratio is to 1, the worse the
trashing is. Note with the patched kernel that there is no swapin
activity indicating that all the pages swapped were really inactive
unused pages.
minorfaults are just minor faults. An increased number of minor faults
can indicate that page reclaim is unmapping the pages but not
swapping them out before they are faulted back in. With the
patched kernel, there is only a small change in minor faults
majorfaults are just major faults in the target workload and a high
number can indicate that a workload is being prematurely
swapped. With the patched kernel, major faults are much reduced. As
there are no swapin's recorded so it's not being swapped. The likely
explanation is that that libraries or configuration files used by
the workload during startup get paged out by the background IO.
Overall with the series applied, there is no noticable performance drop
due to background IO and while there is still some swap activity, it's
tiny and the lack of swapins imply that the swapped pages were inactive
and unused.
3.10.0-rc1 3.10.0-rc1
vanilla lessdisrupt-v4
Page Ins
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Shaohua Li
|
5bc7b8aca9 |
mm: thp: add split tail pages to shrink page list in page reclaim
In page reclaim, huge page is split. split_huge_page() adds tail pages to LRU list. Since we are reclaiming a huge page, it's better we reclaim all subpages of the huge page instead of just the head page. This patch adds split tail pages to shrink page list so the tail pages can be reclaimed soon. Before this patch, run a swap workload: thp_fault_alloc 3492 thp_fault_fallback 608 thp_collapse_alloc 6 thp_collapse_alloc_failed 0 thp_split 916 With this patch: thp_fault_alloc 4085 thp_fault_fallback 16 thp_collapse_alloc 90 thp_collapse_alloc_failed 0 thp_split 1272 fallback allocation is reduced a lot. [akpm@linux-foundation.org: fix CONFIG_SWAP=n build] Signed-off-by: Shaohua Li <shli@fusionio.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Anton Vorontsov
|
70ddf637ee |
memcg: add memory.pressure_level events
With this patch userland applications that want to maintain the interactivity/memory allocation cost can use the pressure level notifications. The levels are defined like this: The "low" level means that the system is reclaiming memory for new allocations. Monitoring this reclaiming activity might be useful for maintaining cache level. Upon notification, the program (typically "Activity Manager") might analyze vmstat and act in advance (i.e. prematurely shutdown unimportant services). The "medium" level means that the system is experiencing medium memory pressure, the system might be making swap, paging out active file caches, etc. Upon this event applications may decide to further analyze vmstat/zoneinfo/memcg or internal memory usage statistics and free any resources that can be easily reconstructed or re-read from a disk. The "critical" level means that the system is actively thrashing, it is about to out of memory (OOM) or even the in-kernel OOM killer is on its way to trigger. Applications should do whatever they can to help the system. It might be too late to consult with vmstat or any other statistics, so it's advisable to take an immediate action. The events are propagated upward until the event is handled, i.e. the events are not pass-through. Here is what this means: for example you have three cgroups: A->B->C. Now you set up an event listener on cgroups A, B and C, and suppose group C experiences some pressure. In this situation, only group C will receive the notification, i.e. groups A and B will not receive it. This is done to avoid excessive "broadcasting" of messages, which disturbs the system and which is especially bad if we are low on memory or thrashing. So, organize the cgroups wisely, or propagate the events manually (or, ask us to implement the pass-through events, explaining why would you need them.) Performance wise, the memory pressure notifications feature itself is lightweight and does not require much of bookkeeping, in contrast to the rest of memcg features. Unfortunately, as of current memcg implementation, pages accounting is an inseparable part and cannot be turned off. The good news is that there are some efforts[1] to improve the situation; plus, implementing the same, fully API-compatible[2] interface for CONFIG_MEMCG=n case (e.g. embedded) is also a viable option, so it will not require any changes on the userland side. [1] http://permalink.gmane.org/gmane.linux.kernel.cgroups/6291 [2] http://lkml.org/lkml/2013/2/21/454 [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix CONFIG_CGROPUPS=n warnings] Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Acked-by: Kirill A. Shutemov <kirill@shutemov.name> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Glauber Costa <glommer@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Leonid Moiseichuk <leonid.moiseichuk@nokia.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: John Stultz <john.stultz@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Hillf Danton
|
2d42a40d59 |
mm/vmscan.c: minor cleanup for kswapd
Local variable total_scanned is no longer used. Signed-off-by: Hillf Danton <dhillf@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Xishi Qiu
|
d72515b85a |
mm/vmscan: fix error return in kswapd_run()
Fix the error return value in kswapd_run(). The bug was introduced by
commit
|
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Zhang Yanfei
|
b21e0b90cc |
vmscan: change type of vm_total_pages to unsigned long
This variable is calculated from nr_free_pagecache_pages so change its type to unsigned long. Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Minchan Kim
|
0e50ce3b50 |
mm: use up free swap space before reaching OOM kill
Recently, Luigi reported there are lots of free swap space when OOM
happens. It's easily reproduced on zram-over-swap, where many instance
of memory hogs are running and laptop_mode is enabled. He said there
was no problem when he disabled laptop_mode. The problem when I
investigate problem is following as.
Assumption for easy explanation: There are no page cache page in system
because they all are already reclaimed.
1. try_to_free_pages disable may_writepage when laptop_mode is enabled.
2. shrink_inactive_list isolates victim pages from inactive anon lru list.
3. shrink_page_list adds them to swapcache via add_to_swap but it doesn't
pageout because sc->may_writepage is 0 so the page is rotated back into
inactive anon lru list. The add_to_swap made the page Dirty by SetPageDirty.
4. 3 couldn't reclaim any pages so do_try_to_free_pages increase priority and
retry reclaim with higher priority.
5. shrink_inactlive_list try to isolate victim pages from inactive anon lru list
but got failed because it try to isolate pages with ISOLATE_CLEAN mode but
inactive anon lru list is full of dirty pages by 3 so it just returns
without any reclaim progress.
6. do_try_to_free_pages doesn't set may_writepage due to zero total_scanned.
Because sc->nr_scanned is increased by shrink_page_list but we don't call
shrink_page_list in 5 due to short of isolated pages.
Above loop is continued until OOM happens.
The problem didn't happen before [1] was merged because old logic's
isolatation in shrink_inactive_list was successful and tried to call
shrink_page_list to pageout them but it still ends up failed to page out
by may_writepage. But important point is that sc->nr_scanned was
increased although we couldn't swap out them so do_try_to_free_pages
could set may_writepages.
Since commit
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Johannes Weiner
|
e3790144c9 |
mm: refactor inactive_file_is_low() to use get_lru_size()
An inactive file list is considered low when its active counterpart is bigger, regardless of whether it is a global zone LRU list or a memcg zone LRU list. The only difference is in how the LRU size is assessed. get_lru_size() does the right thing for both global and memcg reclaim situations. Get rid of inactive_file_is_low_global() and mem_cgroup_inactive_file_is_low() by using get_lru_size() and compare the numbers in common code. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Shaohua Li
|
ec8acf20af |
swap: add per-partition lock for swapfile
swap_lock is heavily contended when I test swap to 3 fast SSD (even slightly slower than swap to 2 such SSD). The main contention comes from swap_info_get(). This patch tries to fix the gap with adding a new per-partition lock. Global data like nr_swapfiles, total_swap_pages, least_priority and swap_list are still protected by swap_lock. nr_swap_pages is an atomic now, it can be changed without swap_lock. In theory, it's possible get_swap_page() finds no swap pages but actually there are free swap pages. But sounds not a big problem. Accessing partition specific data (like scan_swap_map and so on) is only protected by swap_info_struct.lock. Changing swap_info_struct.flags need hold swap_lock and swap_info_struct.lock, because scan_scan_map() will check it. read the flags is ok with either the locks hold. If both swap_lock and swap_info_struct.lock must be hold, we always hold the former first to avoid deadlock. swap_entry_free() can change swap_list. To delete that code, we add a new highest_priority_index. Whenever get_swap_page() is called, we check it. If it's valid, we use it. It's a pity get_swap_page() still holds swap_lock(). But in practice, swap_lock() isn't heavily contended in my test with this patch (or I can say there are other much more heavier bottlenecks like TLB flush). And BTW, looks get_swap_page() doesn't really need the lock. We never free swap_info[] and we check SWAP_WRITEOK flag. The only risk without the lock is we could swapout to some low priority swap, but we can quickly recover after several rounds of swap, so sounds not a big deal to me. But I'd prefer to fix this if it's a real problem. "swap: make each swap partition have one address_space" improved the swapout speed from 1.7G/s to 2G/s. This patch further improves the speed to 2.3G/s, so around 15% improvement. It's a multi-process test, so TLB flush isn't the biggest bottleneck before the patches. [arnd@arndb.de: fix it for nommu] [hughd@google.com: add missing unlock] [minchan@kernel.org: get rid of lockdep whinge on sys_swapon] Signed-off-by: Shaohua Li <shli@fusionio.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Ming Lei
|
21caf2fc19 |
mm: teach mm by current context info to not do I/O during memory allocation
This patch introduces PF_MEMALLOC_NOIO on process flag('flags' field of
'struct task_struct'), so that the flag can be set by one task to avoid
doing I/O inside memory allocation in the task's context.
The patch trys to solve one deadlock problem caused by block device, and
the problem may happen at least in the below situations:
- during block device runtime resume, if memory allocation with
GFP_KERNEL is called inside runtime resume callback of any one of its
ancestors(or the block device itself), the deadlock may be triggered
inside the memory allocation since it might not complete until the block
device becomes active and the involed page I/O finishes. The situation
is pointed out first by Alan Stern. It is not a good approach to
convert all GFP_KERNEL[1] in the path into GFP_NOIO because several
subsystems may be involved(for example, PCI, USB and SCSI may be
involved for usb mass stoarage device, network devices involved too in
the iSCSI case)
- during block device runtime suspend, because runtime resume need to
wait for completion of concurrent runtime suspend.
- during error handling of usb mass storage deivce, USB bus reset will
be put on the device, so there shouldn't have any memory allocation with
GFP_KERNEL during USB bus reset, otherwise the deadlock similar with
above may be triggered. Unfortunately, any usb device may include one
mass storage interface in theory, so it requires all usb interface
drivers to handle the situation. In fact, most usb drivers don't know
how to handle bus reset on the device and don't provide .pre_set() and
.post_reset() callback at all, so USB core has to unbind and bind driver
for these devices. So it is still not practical to resort to GFP_NOIO
for solving the problem.
Also the introduced solution can be used by block subsystem or block
drivers too, for example, set the PF_MEMALLOC_NOIO flag before doing
actual I/O transfer.
It is not a good idea to convert all these GFP_KERNEL in the affected
path into GFP_NOIO because these functions doing that may be implemented
as library and will be called in many other contexts.
In fact, memalloc_noio_flags() can convert some of current static
GFP_NOIO allocation into GFP_KERNEL back in other non-affected contexts,
at least almost all GFP_NOIO in USB subsystem can be converted into
GFP_KERNEL after applying the approach and make allocation with GFP_NOIO
only happen in runtime resume/bus reset/block I/O transfer contexts
generally.
[1], several GFP_KERNEL allocation examples in runtime resume path
- pci subsystem
acpi_os_allocate
<-acpi_ut_allocate
<-ACPI_ALLOCATE_ZEROED
<-acpi_evaluate_object
<-__acpi_bus_set_power
<-acpi_bus_set_power
<-acpi_pci_set_power_state
<-platform_pci_set_power_state
<-pci_platform_power_transition
<-__pci_complete_power_transition
<-pci_set_power_state
<-pci_restore_standard_config
<-pci_pm_runtime_resume
- usb subsystem
usb_get_status
<-finish_port_resume
<-usb_port_resume
<-generic_resume
<-usb_resume_device
<-usb_resume_both
<-usb_runtime_resume
- some individual usb drivers
usblp, uvc, gspca, most of dvb-usb-v2 media drivers, cpia2, az6007, ....
That is just what I have found. Unfortunately, this allocation can only
be found by human being now, and there should be many not found since
any function in the resume path(call tree) may allocate memory with
GFP_KERNEL.
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oneukum@suse.de>
Cc: Jiri Kosina <jiri.kosina@suse.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Greg KH <greg@kroah.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Decotigny <david.decotigny@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Zlatko Calusic
|
258401a60c |
mm: don't wait on congested zones in balance_pgdat()
From: Zlatko Calusic <zlatko.calusic@iskon.hr>
Commit
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Jiang Liu
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b40da04946 |
mm: use zone->present_pages instead of zone->managed_pages where appropriate
Now we have zone->managed_pages for "pages managed by the buddy system in the zone", so replace zone->present_pages with zone->managed_pages if what the user really wants is number of allocatable pages. Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Jiang Liu <jiang.liu@huawei.com> Cc: Maciej Rutecki <maciej.rutecki@gmail.com> Cc: Chris Clayton <chris2553@googlemail.com> Cc: "Rafael J . Wysocki" <rjw@sisk.pl> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Jianguo Wu <wujianguo@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Zlatko Calusic
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dafcb73e38 |
mm: avoid calling pgdat_balanced() needlessly
Now that balance_pgdat() is slightly tidied up, thanks to more capable pgdat_balanced(), it's become obvious that pgdat_balanced() is called to check the status, then break the loop if pgdat is balanced, just to be immediately called again. The second call is completely unnecessary, of course. The patch introduces pgdat_is_balanced boolean, which helps resolve the above suboptimal behavior, with the added benefit of slightly better documenting one other place in the function where we jump and skip lots of code. Signed-off-by: Zlatko Calusic <zlatko.calusic@iskon.hr> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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a394cb8ee6 |
memcg,vmscan: do not break out targeted reclaim without reclaimed pages
Targeted (hard resp soft) reclaim has traditionally tried to scan one group with decreasing priority until nr_to_reclaim (SWAP_CLUSTER_MAX pages) is reclaimed or all priorities are exhausted. The reclaim is then retried until the limit is met. This approach, however, doesn't work well with deeper hierarchies where groups higher in the hierarchy do not have any or only very few pages (this usually happens if those groups do not have any tasks and they have only re-parented pages after some of their children is removed). Those groups are reclaimed with decreasing priority pointlessly as there is nothing to reclaim from them. An easiest fix is to break out of the memcg iteration loop in shrink_zone only if the whole hierarchy has been visited or sufficient pages have been reclaimed. This is also more natural because the reclaimer expects that the hierarchy under the given root is reclaimed. As a result we can simplify the soft limit reclaim which does its own iteration. [yinghan@google.com: break out of the hierarchy loop only if nr_reclaimed exceeded nr_to_reclaim] [akpm@linux-foundation.org: use conventional comparison order] Signed-off-by: Michal Hocko <mhocko@suse.cz> Reported-by: Ying Han <yinghan@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <htejun@gmail.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Li Zefan <lizefan@huawei.com> Signed-off-by: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrew Morton
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62b726c1b3 |
mm/vmscan.c:__zone_reclaim(): replace max_t() with max()
"mm: vmscan: save work scanning (almost) empty LRU lists" made SWAP_CLUSTER_MAX an unsigned long. Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Johannes Weiner
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9b4f98cdac |
mm: vmscan: compaction works against zones, not lruvecs
The restart logic for when reclaim operates back to back with compaction is currently applied on the lruvec level. But this does not make sense, because the container of interest for compaction is a zone as a whole, not the zone pages that are part of a certain memory cgroup. Negative impact is bounded. For one, the code checks that the lruvec has enough reclaim candidates, so it does not risk getting stuck on a condition that can not be fulfilled. And the unfairness of hammering on one particular memory cgroup to make progress in a zone will be amortized by the round robin manner in which reclaim goes through the memory cgroups. Still, this can lead to unnecessary allocation latencies when the code elects to restart on a hard to reclaim or small group when there are other, more reclaimable groups in the zone. Move this logic to the zone level and restart reclaim for all memory cgroups in a zone when compaction requires more free pages from it. [akpm@linux-foundation.org: no need for min_t] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Johannes Weiner
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9a2651140e |
mm: vmscan: clean up get_scan_count()
Reclaim pressure balance between anon and file pages is calculated
through a tuple of numerators and a shared denominator.
Exceptional cases that want to force-scan anon or file pages configure
the numerators and denominator such that one list is preferred, which is
not necessarily the most obvious way:
fraction[0] = 1;
fraction[1] = 0;
denominator = 1;
goto out;
Make this easier by making the force-scan cases explicit and use the
fractionals only in case they are calculated from reclaim history.
[akpm@linux-foundation.org: avoid using unintialized_var()]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Satoru Moriya <satoru.moriya@hds.com>
Cc: Simon Jeons <simon.jeons@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Johannes Weiner
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11d16c25bb |
mm: vmscan: improve comment on low-page cache handling
Fix comment style and elaborate on why anonymous memory is force-scanned when file cache runs low. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Johannes Weiner
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10316b313c |
mm: vmscan: clarify how swappiness, highest priority, memcg interact
A swappiness of 0 has a slightly different meaning for global reclaim (may swap if file cache really low) and memory cgroup reclaim (never swap, ever). In addition, global reclaim at highest priority will scan all LRU lists equal to their size and ignore other balancing heuristics. UNLESS swappiness forbids swapping, then the lists are balanced based on recent reclaim effectiveness. UNLESS file cache is running low, then anonymous pages are force-scanned. This (total mess of a) behaviour is implicit and not obvious from the way the code is organized. At least make it apparent in the code flow and document the conditions. It will be it easier to come up with sane semantics later. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Satoru Moriya <satoru.moriya@hds.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Johannes Weiner
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d778df51c0 |
mm: vmscan: save work scanning (almost) empty LRU lists
In certain cases (kswapd reclaim, memcg target reclaim), a fixed minimum amount of pages is scanned from the LRU lists on each iteration, to make progress. Do not make this minimum bigger than the respective LRU list size, however, and save some busy work trying to isolate and reclaim pages that are not there. Empty LRU lists are quite common with memory cgroups in NUMA environments because there exists a set of LRU lists for each zone for each memory cgroup, while the memory of a single cgroup is expected to stay on just one node. The number of expected empty LRU lists is thus memcgs * (nodes - 1) * lru types Each attempt to reclaim from an empty LRU list does expensive size comparisons between lists, acquires the zone's lru lock etc. Avoid that. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Johannes Weiner
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7c5bd705d8 |
mm: memcg: only evict file pages when we have plenty
Commit
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Greg Kroah-Hartman
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fcb35a9bac |
MM: vmscan: remove __devinit attribute.
CONFIG_HOTPLUG is going away as an option. As a result, the __dev* markings need to be removed. This change removes the use of __devinit from the file. Based on patches originally written by Bill Pemberton, but redone by me in order to handle some of the coding style issues better, by hand. Cc: Bill Pemberton <wfp5p@virginia.edu> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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Zlatko Calusic
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ecccd1248d |
mm: fix null pointer dereference in wait_iff_congested()
An unintended consequence of commit
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Zlatko Calusic
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4ae0a48b5e |
mm: modify pgdat_balanced() so that it also handles order-0
Teach pgdat_balanced() about order-0 allocations so that we can simplify code in a few places in vmstat.c. Suggested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Zlatko Calusic <zlatko.calusic@iskon.hr> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Zlatko Calusic
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cda73a10eb |
mm: do not sleep in balance_pgdat if there's no i/o congestion
On a 4GB RAM machine, where Normal zone is much smaller than DMA32 zone, the Normal zone gets fragmented in time. This requires relatively more pressure in balance_pgdat to get the zone above the required watermark. Unfortunately, the congestion_wait() call in there slows it down for a completely wrong reason, expecting that there's a lot of writeback/swapout, even when there's none (much more common). After a few days, when fragmentation progresses, this flawed logic translates to a very high CPU iowait times, even though there's no I/O congestion at all. If THP is enabled, the problem occurs sooner, but I was able to see it even on !THP kernels, just by giving it a bit more time to occur. The proper way to deal with this is to not wait, unless there's congestion. Thanks to Mel Gorman, we already have the function that perfectly fits the job. The patch was tested on a machine which nicely revealed the problem after only 1 day of uptime, and it's been working great. Signed-off-by: Zlatko Calusic <zlatko.calusic@iskon.hr> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Fengguang Wu
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3cf23841b4 |
mm/vmscan.c: avoid possible deadlock caused by too_many_isolated()
Neil found that if too_many_isolated() returns true while performing
direct reclaim we can end up waiting for other threads to complete their
direct reclaim. If those threads are allowed to enter the FS or IO to
free memory, but this thread is not, then it is possible that those
threads will be waiting on this thread and so we get a circular deadlock.
some task enters direct reclaim with GFP_KERNEL
=> too_many_isolated() false
=> vmscan and run into dirty pages
=> pageout()
=> take some FS lock
=> fs/block code does GFP_NOIO allocation
=> enter direct reclaim again
=> too_many_isolated() true
=> waiting for others to progress, however the other
tasks may be circular waiting for the FS lock..
The fix is to let !__GFP_IO and !__GFP_FS direct reclaims enjoy higher
priority than normal ones, by lowering the throttle threshold for the
latter.
Allowing ~1/8 isolated pages in normal is large enough. For example, for
a 1GB LRU list, that's ~128MB isolated pages, or 1k blocked tasks (each
isolates 32 4KB pages), or 64 blocked tasks per logical CPU (assuming 16
logical CPUs per NUMA node). So it's not likely some CPU goes idle
waiting (when it could make progress) because of this limit: there are
much more sleeping reclaim tasks than the number of CPU, so the task may
well be blocked by some low level queue/lock anyway.
Now !GFP_IOFS reclaims won't be waiting for GFP_IOFS reclaims to progress.
They will be blocked only when there are too many concurrent !GFP_IOFS
reclaims, however that's very unlikely because the IO-less direct reclaims
is able to progress much more faster, and they won't deadlock each other.
The threshold is raised high enough for them, so that there can be
sufficient parallel progress of !GFP_IOFS reclaims.
[akpm@linux-foundation.org: tweak comment]
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Torsten Kaiser <just.for.lkml@googlemail.com>
Tested-by: NeilBrown <neilb@suse.de>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fengguang Wu
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d37dd5dcb9 |
vmscan: comment too_many_isolated()
Comment "Why it's doing so" rather than "What it does" as proposed by Andrew Morton. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Lai Jiangshan
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48fb2e240c |
vmscan: use N_MEMORY instead N_HIGH_MEMORY
N_HIGH_MEMORY stands for the nodes that has normal or high memory. N_MEMORY stands for the nodes that has any memory. The code here need to handle with the nodes which have memory, we should use N_MEMORY instead. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by: Hillf Danton <dhillf@gmail.com> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Lin Feng <linfeng@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Jeff Liu
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6f6313d487 |
mm/vmscan.c: try_to_freeze() returns boolean
kswapd()->try_to_freeze() is defined to return a boolean, so it's better to use a bool to hold its return value. Signed-off-by: Jie Liu <jeff.liu@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Rik van Riel
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e986850598 |
mm,vmscan: only evict file pages when we have plenty
If we have more inactive file pages than active file pages, we skip scanning the active file pages altogether, with the idea that we do not want to evict the working set when there is plenty of streaming IO in the cache. However, the code forgot to also skip scanning anonymous pages in that situation. That leads to the curious situation of keeping the active file pages protected from being paged out when there are lots of inactive file pages, while still scanning and evicting anonymous pages. This patch fixes that situation, by only evicting file pages when we have plenty of them and most are inactive. [akpm@linux-foundation.org: adjust comment layout] Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Kirill A. Shutemov
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d84da3f9e4 |
mm: use IS_ENABLED(CONFIG_COMPACTION) instead of COMPACTION_BUILD
We don't need custom COMPACTION_BUILD anymore, since we have handy IS_ENABLED(). Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Johannes Weiner
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ed23ec4f0a |
mm: vmscan: fix inappropriate zone congestion clearing
commit
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Johannes Weiner
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c702418f8a |
mm: vmscan: do not keep kswapd looping forever due to individual uncompactable zones
When a zone meets its high watermark and is compactable in case of higher order allocations, it contributes to the percentage of the node's memory that is considered balanced. This requirement, that a node be only partially balanced, came about when kswapd was desparately trying to balance tiny zones when all bigger zones in the node had plenty of free memory. Arguably, the same should apply to compaction: if a significant part of the node is balanced enough to run compaction, do not get hung up on that tiny zone that might never get in shape. When the compaction logic in kswapd is reached, we know that at least 25% of the node's memory is balanced properly for compaction (see zone_balanced and pgdat_balanced). Remove the individual zone checks that restart the kswapd cycle. Otherwise, we may observe more endless looping in kswapd where the compaction code loops back to reclaim because of a single zone and reclaim does nothing because the node is considered balanced overall. See for example https://bugzilla.redhat.com/show_bug.cgi?id=866988 Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-and-tested-by: Thorsten Leemhuis <fedora@leemhuis.info> Reported-by: Jiri Slaby <jslaby@suse.cz> Tested-by: John Ellson <john.ellson@comcast.net> Tested-by: Zdenek Kabelac <zkabelac@redhat.com> Tested-by: Bruno Wolff III <bruno@wolff.to> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Johannes Weiner
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60cefed485 |
mm: vmscan: fix endless loop in kswapd balancing
Kswapd does not in all places have the same criteria for a balanced zone. Zones are only being reclaimed when their high watermark is breached, but compaction checks loop over the zonelist again when the zone does not meet the low watermark plus two times the size of the allocation. This gets kswapd stuck in an endless loop over a small zone, like the DMA zone, where the high watermark is smaller than the compaction requirement. Add a function, zone_balanced(), that checks the watermark, and, for higher order allocations, if compaction has enough free memory. Then use it uniformly to check for balanced zones. This makes sure that when the compaction watermark is not met, at least reclaim happens and progress is made - or the zone is declared unreclaimable at some point and skipped entirely. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: George Spelvin <linux@horizon.com> Reported-by: Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de> Reported-by: Tomas Racek <tracek@redhat.com> Tested-by: Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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50694c28f1 |
mm: vmscan: check for fatal signals iff the process was throttled
Commit
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Mel Gorman
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96710098ee |
mm: revert "mm: vmscan: scale number of pages reclaimed by reclaim/compaction based on failures"
Jiri Slaby reported the following: (It's an effective revert of "mm: vmscan: scale number of pages reclaimed by reclaim/compaction based on failures".) Given kswapd had hours of runtime in ps/top output yesterday in the morning and after the revert it's now 2 minutes in sum for the last 24h, I would say, it's gone. The intention of the patch in question was to compensate for the loss of lumpy reclaim. Part of the reason lumpy reclaim worked is because it aggressively reclaimed pages and this patch was meant to be a sane compromise. When compaction fails, it gets deferred and both compaction and reclaim/compaction is deferred avoid excessive reclaim. However, since commit |
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Takamori Yamaguchi
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b0a8cc58e6 |
mm: bugfix: set current->reclaim_state to NULL while returning from kswapd()
In kswapd(), set current->reclaim_state to NULL before returning, as current->reclaim_state holds reference to variable on kswapd()'s stack. In rare cases, while returning from kswapd() during memory offlining, __free_slab() and freepages() can access the dangling pointer of current->reclaim_state. Signed-off-by: Takamori Yamaguchi <takamori.yamaguchi@jp.sony.com> Signed-off-by: Aaditya Kumar <aaditya.kumar@ap.sony.com> Acked-by: David Rientjes <rientjes@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Minchan Kim
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e46a28790e |
CMA: migrate mlocked pages
Presently CMA cannot migrate mlocked pages so it ends up failing to allocate contiguous memory space. This patch makes mlocked pages be migrated out. Of course, it can affect realtime processes but in CMA usecase, contiguous memory allocation failing is far worse than access latency to an mlocked page being variable while CMA is running. If someone wants to make the system realtime, he shouldn't enable CMA because stalls can still happen at random times. [akpm@linux-foundation.org: tweak comment text, per Mel] Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Hugh Dickins
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39b5f29ac1 |
mm: remove vma arg from page_evictable
page_evictable(page, vma) is an irritant: almost all its callers pass NULL for vma. Remove the vma arg and use mlocked_vma_newpage(vma, page) explicitly in the couple of places it's needed. But in those places we don't even need page_evictable() itself! They're dealing with a freshly allocated anonymous page, which has no "mapping" and cannot be mlocked yet. Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michel Lespinasse <walken@google.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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62997027ca |
mm: compaction: clear PG_migrate_skip based on compaction and reclaim activity
Compaction caches if a pageblock was scanned and no pages were isolated so that the pageblocks can be skipped in the future to reduce scanning. This information is not cleared by the page allocator based on activity due to the impact it would have to the page allocator fast paths. Hence there is a requirement that something clear the cache or pageblocks will be skipped forever. Currently the cache is cleared if there were a number of recent allocation failures and it has not been cleared within the last 5 seconds. Time-based decisions like this are terrible as they have no relationship to VM activity and is basically a big hammer. Unfortunately, accurate heuristics would add cost to some hot paths so this patch implements a rough heuristic. There are two cases where the cache is cleared. 1. If a !kswapd process completes a compaction cycle (migrate and free scanner meet), the zone is marked compact_blockskip_flush. When kswapd goes to sleep, it will clear the cache. This is expected to be the common case where the cache is cleared. It does not really matter if kswapd happens to be asleep or going to sleep when the flag is set as it will be woken on the next allocation request. 2. If there have been multiple failures recently and compaction just finished being deferred then a process will clear the cache and start a full scan. This situation happens if there are multiple high-order allocation requests under heavy memory pressure. The clearing of the PG_migrate_skip bits and other scans is inherently racy but the race is harmless. For allocations that can fail such as THP, they will simply fail. For requests that cannot fail, they will retry the allocation. Tests indicated that scanning rates were roughly similar to when the time-based heuristic was used and the allocation success rates were similar. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Richard Davies <richard@arachsys.com> Cc: Shaohua Li <shli@kernel.org> Cc: Avi Kivity <avi@redhat.com> Cc: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Minchan Kim
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02c6de8d75 |
mm: cma: discard clean pages during contiguous allocation instead of migration
Drop clean cache pages instead of migration during alloc_contig_range() to minimise allocation latency by reducing the amount of migration that is necessary. It's useful for CMA because latency of migration is more important than evicting the background process's working set. In addition, as pages are reclaimed then fewer free pages for migration targets are required so it avoids memory reclaiming to get free pages, which is a contributory factor to increased latency. I measured elapsed time of __alloc_contig_migrate_range() which migrates 10M in 40M movable zone in QEMU machine. Before - 146ms, After - 7ms [akpm@linux-foundation.org: fix nommu build] Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Minchan Kim <minchan@kernel.org> Reviewed-by: Mel Gorman <mgorman@suse.de> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Cc: Rik van Riel <riel@redhat.com> Tested-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Gavin Shan
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d5dc0ad928 |
mm/vmscan: fix error number for failed kthread
Fix the return value while failing to create the kswapd kernel thread. Also, the error message is prioritized as KERN_ERR. Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com> Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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83fde0f228 |
mm: vmscan: scale number of pages reclaimed by reclaim/compaction based on failures
If allocation fails after compaction then compaction may be deferred for a number of allocation attempts. If there are subsequent failures, compact_defer_shift is increased to defer for longer periods. This patch uses that information to scale the number of pages reclaimed with compact_defer_shift until allocations succeed again. The rationale is that reclaiming the normal number of pages still allowed compaction to fail and its success depends on the number of pages. If it's failing, reclaim more pages until it succeeds again. Note that this is not implying that VM reclaim is not reclaiming enough pages or that its logic is broken. try_to_free_pages() always asks for SWAP_CLUSTER_MAX pages to be reclaimed regardless of order and that is what it does. Direct reclaim stops normally with this check. if (sc->nr_reclaimed >= sc->nr_to_reclaim) goto out; should_continue_reclaim delays when that check is made until a minimum number of pages for reclaim/compaction are reclaimed. It is possible that this patch could instead set nr_to_reclaim in try_to_free_pages() and drive it from there but that's behaves differently and not necessarily for the better. If driven from do_try_to_free_pages(), it is also possible that priorities will rise. When they reach DEF_PRIORITY-2, it will also start stalling and setting pages for immediate reclaim which is more disruptive than not desirable in this case. That is a more wide-reaching change that could cause another regression related to THP requests causing interactive jitter. [akpm@linux-foundation.org: fix build] Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Wen Congyang
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18b48d5873 |
memory hotplug: reset pgdat->kswapd to NULL if creating kernel thread fails
If kthread_run() fails, pgdat->kswapd contains errno. When we stop this thread, we only check whether pgdat->kswapd is NULL and access it. If it contains errno, it will cause page fault. Reset pgdat->kswapd to NULL when creating kernel thread fails can avoid this problem. Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Tim Chen
|
69980e3175 |
memcg: gix memory accounting scalability in shrink_page_list
I noticed in a multi-process parallel files reading benchmark I ran on a 8
socket machine, throughput slowed down by a factor of 8 when I ran the
benchmark within a cgroup container. I traced the problem to the
following code path (see below) when we are trying to reclaim memory from
file cache. The res_counter_uncharge function is called on every page
that's reclaimed and created heavy lock contention. The patch below
allows the reclaimed pages to be uncharged from the resource counter in
batch and recovered the regression.
Tim
40.67% usemem [kernel.kallsyms] [k] _raw_spin_lock
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--- _raw_spin_lock
|
|--92.61%-- res_counter_uncharge
| |
| |--100.00%-- __mem_cgroup_uncharge_common
| | |
| | |--100.00%-- mem_cgroup_uncharge_cache_page
| | | __remove_mapping
| | | shrink_page_list
| | | shrink_inactive_list
| | | shrink_mem_cgroup_zone
| | | shrink_zone
| | | do_try_to_free_pages
| | | try_to_free_pages
| | | __alloc_pages_nodemask
| | | alloc_pages_current
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Hugh Dickins
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c3b94f44fc |
memcg: further prevent OOM with too many dirty pages
The may_enter_fs test turns out to be too restrictive: though I saw no problem with it when testing on 3.5-rc6, it very soon OOMed when I tested on 3.5-rc6-mm1. I don't know what the difference there is, perhaps I just slightly changed the way I started off the testing: dd if=/dev/zero of=/mnt/temp bs=1M count=1024; rm -f /mnt/temp; sync repeatedly, in 20M memory.limit_in_bytes cgroup to ext4 on USB stick. ext4 (and gfs2 and xfs) turn out to allocate new pages for writing with AOP_FLAG_NOFS: that seems a little worrying, and it's unclear to me why the transaction needs to be started even before allocating pagecache memory. But it may not be worth worrying about these days: if direct reclaim avoids FS writeback, does __GFP_FS now mean anything? Anyway, we insisted on the may_enter_fs test to avoid hangs with the loop device; but since that also masks off __GFP_IO, we can test for __GFP_IO directly, ignoring may_enter_fs and __GFP_FS. But even so, the test still OOMs sometimes: when originally testing on 3.5-rc6, it OOMed about one time in five or ten; when testing just now on 3.5-rc6-mm1, it OOMed on the first iteration. This residual problem comes from an accumulation of pages under ordinary writeback, not marked PageReclaim, so rightly not causing the memcg check to wait on their writeback: these too can prevent shrink_page_list() from freeing any pages, so many times that memcg reclaim fails and OOMs. Deal with these in the same way as direct reclaim now deals with dirty FS pages: mark them PageReclaim. It is appropriate to rotate these to tail of list when writepage completes, but more importantly, the PageReclaim flag makes memcg reclaim wait on them if encountered again. Increment NR_VMSCAN_IMMEDIATE? That's arguable: I chose not. Setting PageReclaim here may occasionally race with end_page_writeback() clearing it: lru_deactivate_fn() already faced the same race, and correctly concluded that the window is small and the issue non-critical. With these changes, the test runs indefinitely without OOMing on ext4, ext3 and ext2: I'll move on to test with other filesystems later. Trivia: invert conditions for a clearer block without an else, and goto keep_locked to do the unlock_page. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Ying Han <yinghan@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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e62e384e9d |
memcg: prevent OOM with too many dirty pages
The current implementation of dirty pages throttling is not memcg aware which makes it easy to have memcg LRUs full of dirty pages. Without throttling, these LRUs can be scanned faster than the rate of writeback, leading to memcg OOM conditions when the hard limit is small. This patch fixes the problem by throttling the allocating process (possibly a writer) during the hard limit reclaim by waiting on PageReclaim pages. We are waiting only for PageReclaim pages because those are the pages that made one full round over LRU and that means that the writeback is much slower than scanning. The solution is far from being ideal - long term solution is memcg aware dirty throttling - but it is meant to be a band aid until we have a real fix. We are seeing this happening during nightly backups which are placed into containers to prevent from eviction of the real working set. The change affects only memcg reclaim and only when we encounter PageReclaim pages which is a signal that the reclaim doesn't catch up on with the writers so somebody should be throttled. This could be potentially unfair because it could be somebody else from the group who gets throttled on behalf of the writer but as writers need to allocate as well and they allocate in higher rate the probability that only innocent processes would be penalized is not that high. I have tested this change by a simple dd copying /dev/zero to tmpfs or ext3 running under small memcg (1G copy under 5M, 60M, 300M and 2G containers) and dd got killed by OOM killer every time. With the patch I could run the dd with the same size under 5M controller without any OOM. The issue is more visible with slower devices for output. * With the patch ================ * tmpfs size=2G --------------- $ vim cgroup_cache_oom_test.sh $ ./cgroup_cache_oom_test.sh 5M using Limit 5M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 30.4049 s, 34.5 MB/s $ ./cgroup_cache_oom_test.sh 60M using Limit 60M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 31.4561 s, 33.3 MB/s $ ./cgroup_cache_oom_test.sh 300M using Limit 300M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 20.4618 s, 51.2 MB/s $ ./cgroup_cache_oom_test.sh 2G using Limit 2G for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 1.42172 s, 738 MB/s * ext3 ------ $ ./cgroup_cache_oom_test.sh 5M using Limit 5M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 27.9547 s, 37.5 MB/s $ ./cgroup_cache_oom_test.sh 60M using Limit 60M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 30.3221 s, 34.6 MB/s $ ./cgroup_cache_oom_test.sh 300M using Limit 300M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 24.5764 s, 42.7 MB/s $ ./cgroup_cache_oom_test.sh 2G using Limit 2G for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 3.35828 s, 312 MB/s * Without the patch =================== * tmpfs size=2G --------------- $ ./cgroup_cache_oom_test.sh 5M using Limit 5M for group ./cgroup_cache_oom_test.sh: line 46: 4668 Killed dd if=/dev/zero of=$OUT/zero bs=1M count=$count $ ./cgroup_cache_oom_test.sh 60M using Limit 60M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 25.4989 s, 41.1 MB/s $ ./cgroup_cache_oom_test.sh 300M using Limit 300M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 24.3928 s, 43.0 MB/s $ ./cgroup_cache_oom_test.sh 2G using Limit 2G for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 1.49797 s, 700 MB/s * ext3 ------ $ ./cgroup_cache_oom_test.sh 5M using Limit 5M for group ./cgroup_cache_oom_test.sh: line 46: 4689 Killed dd if=/dev/zero of=$OUT/zero bs=1M count=$count $ ./cgroup_cache_oom_test.sh 60M using Limit 60M for group ./cgroup_cache_oom_test.sh: line 46: 4692 Killed dd if=/dev/zero of=$OUT/zero bs=1M count=$count $ ./cgroup_cache_oom_test.sh 300M using Limit 300M for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 20.248 s, 51.8 MB/s $ ./cgroup_cache_oom_test.sh 2G using Limit 2G for group 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 2.85201 s, 368 MB/s [akpm@linux-foundation.org: tweak changelog, reordered the test to optimize for CONFIG_CGROUP_MEM_RES_CTLR=n] [hughd@google.com: fix deadlock with loop driver] Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Ying Han <yinghan@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
68243e76ee |
mm: account for the number of times direct reclaimers get throttled
Under significant pressure when writing back to network-backed storage, direct reclaimers may get throttled. This is expected to be a short-lived event and the processes get woken up again but processes do get stalled. This patch counts how many times such stalling occurs. It's up to the administrator whether to reduce these stalls by increasing min_free_kbytes. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Cc: Neil Brown <neilb@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
5515061d22 |
mm: throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
If swap is backed by network storage such as NBD, there is a risk that a large number of reclaimers can hang the system by consuming all PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune min_free_kbytes in advance which is a bit fragile. This patch throttles direct reclaimers if half the PF_MEMALLOC reserves are in use. If the system is routinely getting throttled the system administrator can increase min_free_kbytes so degradation is smoother but the system will keep running. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Cc: Neil Brown <neilb@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
