linux/mm
Dan Magenheimer e3483a5f3a frontswap: support exclusive gets if tmem backend is capable
Tmem, as originally specified, assumes that "get" operations
performed on persistent pools never flush the page of data out
of tmem on a successful get, waiting instead for a flush
operation.  This is intended to mimic the model of a swap
disk, where a disk read is non-destructive.  Unlike a
disk, however, freeing up the RAM can be valuable.  Over
the years that frontswap was in the review process, several
reviewers (and notably Hugh Dickins in 2010) pointed out that
this would result, at least temporarily, in two copies of the
data in RAM: one (compressed for zcache) copy in tmem,
and one copy in the swap cache.  We wondered if this could
be done differently, at least optionally.

This patch allows tmem backends to instruct the frontswap
code that this backend performs exclusive gets.  Zcache2
already contains hooks to support this feature.  Other
backends are completely unaffected unless/until they are
updated to support this feature.

While it is not clear that exclusive gets are a performance
win on all workloads at all times, this small patch allows for
experimentation by backends.

P.S. Let's not quibble about the naming of "get" vs "read" vs
"load" etc.  The naming is currently horribly inconsistent between
cleancache and frontswap and existing tmem backends, so will need
to be straightened out as a separate patch.  "Get" is used
by the tmem architecture spec, existing backends, and
all documentation and presentation material so I am
using it in this patch.

Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-09-21 10:38:12 -04:00
..
backing-dev.c mm: prepare for removal of obsolete /proc/sys/vm/nr_pdflush_threads 2012-07-31 18:42:40 -07:00
bootmem.c bootmem: make ___alloc_bootmem_node_nopanic() really nopanic 2012-07-17 16:21:29 -07:00
bounce.c bounce: allow use of bounce pool via config option 2012-07-18 16:40:35 -04:00
cleancache.c ->encode_fh() API change 2012-05-29 23:28:33 -04:00
compaction.c mm: have order > 0 compaction start off where it left 2012-07-31 18:42:43 -07:00
debug-pagealloc.c mm, x86: Remove debug_pagealloc_enabled 2011-12-06 09:24:07 +01:00
dmapool.c mm: fix implicit stat.h usage in dmapool.c 2011-10-31 09:20:12 -04:00
fadvise.c mm, fadvise: don't return -EINVAL when filesystem cannot implement fadvise() 2012-07-31 18:42:42 -07:00
failslab.c switch debugfs to umode_t 2012-01-03 22:54:56 -05:00
filemap_xip.c fs: Protect write paths by sb_start_write - sb_end_write 2012-07-31 09:45:47 +04:00
filemap.c fs: Protect write paths by sb_start_write - sb_end_write 2012-07-31 09:45:47 +04:00
fremap.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
frontswap.c frontswap: support exclusive gets if tmem backend is capable 2012-09-21 10:38:12 -04:00
highmem.c mm: add support for direct_IO to highmem pages 2012-07-31 18:42:47 -07:00
huge_memory.c mm/memcg: apply add/del_page to lruvec 2012-05-29 16:22:28 -07:00
hugetlb_cgroup.c hugetlb/cgroup: remove exclude and wakeup rmdir calls from migrate 2012-07-31 18:42:41 -07:00
hugetlb.c mm: hugetlbfs: close race during teardown of hugetlbfs shared page tables 2012-07-31 18:42:50 -07:00
hwpoison-inject.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
init-mm.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
internal.h netvm: allow skb allocation to use PFMEMALLOC reserves 2012-07-31 18:42:46 -07:00
Kconfig mm: factor out memory isolate functions 2012-07-31 18:42:45 -07:00
Kconfig.debug mm: more intensive memory corruption debugging 2012-01-10 16:30:42 -08:00
kmemcheck.c
kmemleak-test.c kmemleak: remove memset by using kzalloc 2011-01-27 18:31:51 +00:00
kmemleak.c kmemleak: Disable early logging when kmemleak is off by default 2012-01-20 16:57:05 +00:00
ksm.c ksm: cleanup: introduce find_mergeable_vma() 2012-03-21 17:54:59 -07:00
maccess.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
madvise.c mm: Hold a file reference in madvise_remove 2012-07-06 10:34:38 -07:00
Makefile mm: factor out memory isolate functions 2012-07-31 18:42:45 -07:00
memblock.c mm/memblock.c:memblock_double_array(): cosmetic cleanups 2012-07-31 18:42:41 -07:00
memcontrol.c memcg: add mem_cgroup_from_css() helper 2012-07-31 18:42:49 -07:00
memory_hotplug.c mm/hotplug: free zone->pageset when a zone becomes empty 2012-07-31 18:42:44 -07:00
memory-failure.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
memory.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-08-01 10:26:23 -07:00
mempolicy.c Merge branch 'slab/next' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux 2012-07-30 11:32:24 -07:00
mempool.c mempool: add @gfp_mask to mempool_create_node() 2012-06-25 11:53:47 +02:00
migrate.c mm: memcg: fix compaction/migration failing due to memcg limits 2012-07-31 18:42:48 -07:00
mincore.c mm: thp: fix pmd_bad() triggering in code paths holding mmap_sem read mode 2012-03-21 17:54:54 -07:00
mlock.c vm: avoid using find_vma_prev() unnecessarily 2012-03-06 18:23:36 -08:00
mm_init.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
mmap.c Merge branch 'akpm' (Andrew's patch-bomb) 2012-07-31 19:25:39 -07:00
mmu_context.c mm, counters: remove task argument to sync_mm_rss() and __sync_task_rss_stat() 2012-03-21 17:54:59 -07:00
mmu_notifier.c mm: mmu_notifier: fix freed page still mapped in secondary MMU 2012-07-31 18:42:49 -07:00
mmzone.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
mprotect.c Merge branch 'akpm' (Andrew's patch-bomb) 2012-03-22 09:04:48 -07:00
mremap.c mm: account the total_vm in the vm_stat_account() 2012-07-31 18:42:39 -07:00
msync.c
nobootmem.c memblock: free allocated memblock_reserved_regions later 2012-07-11 16:04:50 -07:00
nommu.c nommu: fix compilation of nommu.c 2012-06-04 17:17:31 -04:00
oom_kill.c mm, memcg: move all oom handling to memcontrol.c 2012-07-31 18:42:45 -07:00
page_alloc.c mm: remove node_start_pfn checking in new WARN_ON for now 2012-08-02 10:37:03 -07:00
page_cgroup.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
page_io.c mm: add support for direct_IO to highmem pages 2012-07-31 18:42:47 -07:00
page_isolation.c memory-hotplug: fix kswapd looping forever problem 2012-07-31 18:42:45 -07:00
page-writeback.c writeback: Fix some comment errors 2012-06-09 19:54:47 +08:00
pagewalk.c mm: fix kernel-doc warnings 2012-06-20 14:39:36 -07:00
percpu-km.c
percpu-vm.c mm: fix kernel-doc warnings 2012-06-20 14:39:36 -07:00
percpu.c kmemleak: Fix the kmemleak tracking of the percpu areas with !SMP 2012-05-09 10:13:29 -07:00
pgtable-generic.c arch/tile: allow building Linux with transparent huge pages enabled 2012-05-25 12:48:21 -04:00
prio_tree.c sanitize <linux/prefetch.h> usage 2011-05-20 12:50:29 -07:00
process_vm_access.c aio/vfs: cleanup of rw_copy_check_uvector() and compat_rw_copy_check_uvector() 2012-05-31 17:49:32 -07:00
quicklist.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
readahead.c mm: move readahead syscall to mm/readahead.c 2012-05-29 16:22:23 -07:00
rmap.c mm: remove swap token code 2012-05-29 16:22:19 -07:00
shmem.c tmpfs: distribute interleave better across nodes 2012-07-31 18:42:50 -07:00
slab_common.c mm: Fix build warning in kmem_cache_create() 2012-07-30 13:15:40 +03:00
slab.c mm: micro-optimise slab to avoid a function call 2012-07-31 18:42:46 -07:00
slab.h mm, sl[aou]b: Use a common mutex definition 2012-07-09 12:13:41 +03:00
slob.c slob: Fix early boot kernel crash 2012-07-12 10:13:22 +03:00
slub.c mm: slub: optimise the SLUB fast path to avoid pfmemalloc checks 2012-07-31 18:42:45 -07:00
sparse-vmemmap.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
sparse.c mm/sparse: remove index_init_lock 2012-07-31 18:42:49 -07:00
swap_state.c mm: add support for a filesystem to activate swap files and use direct_IO for writing swap pages 2012-07-31 18:42:47 -07:00
swap.c mm: add support for direct_IO to highmem pages 2012-07-31 18:42:47 -07:00
swapfile.c mm: swapfile: clean up unuse_pte race handling 2012-07-31 18:42:48 -07:00
truncate.c mm/fs: remove truncate_range 2012-05-29 16:22:23 -07:00
util.c new helper: vm_mmap_pgoff() 2012-06-01 10:37:18 -04:00
vmalloc.c mm: make vb_alloc() more foolproof 2012-07-31 18:42:39 -07:00
vmscan.c memcg: gix memory accounting scalability in shrink_page_list 2012-07-31 18:42:49 -07:00
vmstat.c mm: account for the number of times direct reclaimers get throttled 2012-07-31 18:42:46 -07:00