Knowing the portion of memory that is not used by a certain application or
memory cgroup (idle memory) can be useful for partitioning the system
efficiently, e.g. by setting memory cgroup limits appropriately.
Currently, the only means to estimate the amount of idle memory provided
by the kernel is /proc/PID/{clear_refs,smaps}: the user can clear the
access bit for all pages mapped to a particular process by writing 1 to
clear_refs, wait for some time, and then count smaps:Referenced. However,
this method has two serious shortcomings:
- it does not count unmapped file pages
- it affects the reclaimer logic
To overcome these drawbacks, this patch introduces two new page flags,
Idle and Young, and a new sysfs file, /sys/kernel/mm/page_idle/bitmap.
A page's Idle flag can only be set from userspace by setting bit in
/sys/kernel/mm/page_idle/bitmap at the offset corresponding to the page,
and it is cleared whenever the page is accessed either through page tables
(it is cleared in page_referenced() in this case) or using the read(2)
system call (mark_page_accessed()). Thus by setting the Idle flag for
pages of a particular workload, which can be found e.g. by reading
/proc/PID/pagemap, waiting for some time to let the workload access its
working set, and then reading the bitmap file, one can estimate the amount
of pages that are not used by the workload.
The Young page flag is used to avoid interference with the memory
reclaimer. A page's Young flag is set whenever the Access bit of a page
table entry pointing to the page is cleared by writing to the bitmap file.
If page_referenced() is called on a Young page, it will add 1 to its
return value, therefore concealing the fact that the Access bit was
cleared.
Note, since there is no room for extra page flags on 32 bit, this feature
uses extended page flags when compiled on 32 bit.
[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: kpageidle requires an MMU]
[akpm@linux-foundation.org: decouple from page-flags rework]
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some of the 00-INDEX files are somewhat outdated and some folders does
not contain 00-INDEX at all. Only outdated (with the notably exception
of spi) indexes are touched here, the 169 folders without 00-INDEX has
not been touched.
New 00-INDEX
- spi/* was added in a series of commits dating back to 2006
Added files (missing in (*/)00-INDEX)
- dmatest.txt was added by commit 851b7e16a0 ("dmatest: run test via
debugfs")
- this_cpu_ops.txt was added by commit a1b2a555d6 ("percpu: add
documentation on this_cpu operations")
- ww-mutex-design.txt was added by commit 040a0a3710 ("mutex: Add
support for wound/wait style locks")
- bcache.txt was added by commit cafe563591 ("bcache: A block layer
cache")
- kernel-per-CPU-kthreads.txt was added by commit 49717cb404
("kthread: Document ways of reducing OS jitter due to per-CPU
kthreads")
- phy.txt was added by commit ff76496347 ("drivers: phy: add generic
PHY framework")
- block/null_blk was added by commit 12f8f4fc03 ("null_blk:
documentation")
- module-signing.txt was added by commit 3cafea3076 ("Add
Documentation/module-signing.txt file")
- assoc_array.txt was added by commit 3cb989501c ("Add a generic
associative array implementation.")
- arm/IXP4xx was part of the initial repo
- arm/cluster-pm-race-avoidance.txt was added by commit 7fe31d28e8
("ARM: mcpm: introduce helpers for platform coherency exit/setup")
- arm/firmware.txt was added by commit 7366b92a77 ("ARM: Add
interface for registering and calling firmware-specific operations")
- arm/kernel_mode_neon.txt was added by commit 2afd0a0524 ("ARM:
7825/1: document the use of NEON in kernel mode")
- arm/tcm.txt was added by commit bc581770cf ("ARM: 5580/2: ARM TCM
(Tightly-Coupled Memory) support v3")
- arm/vlocks.txt was added by commit 9762f12d3e ("ARM: mcpm: Add
baremetal voting mutexes")
- blackfin/gptimers-example.c, Makefile was added by commit
4b60779d5e ("Blackfin: add an example showing how to use the
gptimers API")
- devicetree/usage-model.txt was added by commit 31134efc68 ("dt:
Linux DT usage model documentation")
- fb/api.txt was added by commit fb21c2f428 ("fbdev: Add FOURCC-based
format configuration API")
- fb/sm501.txt was added by commit e6a0498071 ("video, sm501: add
edid and commandline support")
- fb/udlfb.txt was added by commit 96f8d864af ("fbdev: move udlfb out
of staging.")
- filesystems/Makefile was added by commit 1e0051ae48
("Documentation/fs/: split txt and source files")
- filesystems/nfs/nfsd-admin-interfaces.txt was added by commit
8a4c6e19cf ("nfsd: document kernel interfaces for nfsd
configuration")
- ide/warm-plug-howto.txt was added by commit f74c91413e ("ide: add
warm-plug support for IDE devices (take 2)")
- laptops/Makefile was added by commit d49129accc
("Documentation/laptop/: split txt and source files")
- leds/leds-blinkm.txt was added by commit b54cf35a7f ("LEDS: add
BlinkM RGB LED driver, documentation and update MAINTAINERS")
- leds/ledtrig-oneshot.txt was added by commit 5e417281cd ("leds: add
oneshot trigger")
- leds/ledtrig-transient.txt was added by commit 44e1e9f8e7 ("leds:
add new transient trigger for one shot timer activation")
- m68k/README.buddha was part of the initial repo
- networking/LICENSE.(qla3xxx|qlcnic|qlge) was added by commits
40839129f7, c4e84bde1d, 5a4faa8737
- networking/Makefile was added by commit 3794f3e812 ("docsrc: build
Documentation/ sources")
- networking/i40evf.txt was added by commit 105bf2fe6b ("i40evf: add
driver to kernel build system")
- networking/ipsec.txt was added by commit b3c6efbc36 ("xfrm: Add
file to document IPsec corner case")
- networking/mac80211-auth-assoc-deauth.txt was added by commit
3cd7920a2b ("mac80211: add auth/assoc/deauth flow diagram")
- networking/netlink_mmap.txt was added by commit 5683264c39
("netlink: add documentation for memory mapped I/O")
- networking/nf_conntrack-sysctl.txt was added by commit c9f9e0e159
("netfilter: doc: add nf_conntrack sysctl api documentation") lan)
- networking/team.txt was added by commit 3d249d4ca7 ("net: introduce
ethernet teaming device")
- networking/vxlan.txt was added by commit d342894c5d ("vxlan:
virtual extensible lan")
- power/runtime_pm.txt was added by commit 5e928f77a0 ("PM: Introduce
core framework for run-time PM of I/O devices (rev. 17)")
- power/charger-manager.txt was added by commit 3bb3dbbd56
("power_supply: Add initial Charger-Manager driver")
- RCU/lockdep-splat.txt was added by commit d7bd2d68aa ("rcu:
Document interpretation of RCU-lockdep splats")
- s390/kvm.txt was added by 5ecee4b (KVM: s390: API documentation)
- s390/qeth.txt was added by commit b4d72c08b3 ("qeth: bridgeport
support - basic control")
- scheduler/sched-bwc.txt was added by commit 88ebc08ea9 ("sched: Add
documentation for bandwidth control")
- scsi/advansys.txt was added by commit 4bd6d7f356 ("[SCSI] advansys:
Move documentation to Documentation/scsi")
- scsi/bfa.txt was added by commit 1ec90174bd ("[SCSI] bfa: add
readme file")
- scsi/bnx2fc.txt was added by commit 12b8fc10ea ("[SCSI] bnx2fc: Add
driver documentation")
- scsi/cxgb3i.txt was added by commit c3673464eb ("[SCSI] cxgb3i: Add
cxgb3i iSCSI driver.")
- scsi/hpsa.txt was added by commit 992ebcf14f ("[SCSI] hpsa: Add
hpsa.txt to Documentation/scsi")
- scsi/link_power_management_policy.txt was added by commit
ca77329fb7 ("[libata] Link power management infrastructure")
- scsi/osd.txt was added by commit 78e0c621de ("[SCSI] osd:
Documentation for OSD library")
- scsi/scsi-parameter.txt was created/moved by commit 163475fb11
("Documentation: move SCSI parameters to their own text file")
- serial/driver was part of the initial repo
- serial/n_gsm.txt was added by commit 323e84122e ("n_gsm: add a
documentation")
- timers/Makefile was added by commit 3794f3e812 ("docsrc: build
Documentation/ sources")
- virt/kvm/s390.txt was added by commit d9101fca3d ("KVM: s390:
diagnose call documentation")
- vm/split_page_table_lock was added by commit 49076ec2cc ("mm:
dynamically allocate page->ptl if it cannot be embedded to struct
page")
- w1/slaves/w1_ds28e04 was added by commit fbf7f7b4e2 ("w1: Add
1-wire slave device driver for DS28E04-100")
- w1/masters/omap-hdq was added by commit e0a29382c6 ("hdq:
documentation for OMAP HDQ")
- x86/early-microcode.txt was added by commit 0d91ea86a8 ("x86, doc:
Documentation for early microcode loading")
- x86/earlyprintk.txt was added by commit a1aade4788 ("x86/doc:
mini-howto for using earlyprintk=dbgp")
- x86/entry_64.txt was added by commit 8b4777a4b5 ("x86-64: Document
some of entry_64.S")
- x86/pat.txt was added by commit d27554d874 ("x86: PAT
documentation")
Moved files
- arm/kernel_user_helpers.txt was moved out of arch/arm/kernel by
commit 37b8304642 ("ARM: kuser: move interface documentation out of
the source code")
- efi-stub.txt was moved out of x86/ and down into Documentation/ in
commit 4172fe2f8a ("EFI stub documentation updates")
- laptops/hpfall.c was moved out of hwmon/ and into laptops/ in commit
efcfed9bad ("Move hp_accel to drivers/platform/x86")
- commit 5616c23ad9 ("x86: doc: move x86-generic documentation from
Doc/x86/i386"):
* x86/usb-legacy-support.txt
* x86/boot.txt
* x86/zero_page.txt
- power/video_extension.txt was moved to acpi in commit 70e66e4df1
("ACPI / video: move video_extension.txt to Documentation/acpi")
Removed files (left in 00-INDEX)
- memory.txt was removed by commit 00ea8990aa ("memory.txt: remove
stray information")
- gpio.txt was moved to gpio/ in commit fd8e198cfc ("Documentation:
gpiolib: document new interface")
- networking/DLINK.txt was removed by commit 168e06ae26
("drivers/net: delete old parallel port de600/de620 drivers")
- serial/hayes-esp.txt was removed by commit f53a2ade0b ("tty: esp:
remove broken driver")
- s390/TAPE was removed by commit 9e280f6693 ("[S390] remove tape
block docu")
- vm/locking was removed by commit 57ea8171d2 ("mm: documentation:
remove hopelessly out-of-date locking doc")
- laptops/acer-wmi.txt was remvoed by commit 020036678e ("acer-wmi:
Delete out-of-date documentation")
Typos/misc issues
- rpc-server-gss.txt was added as knfsd-rpcgss.txt in commit
030d794bf4 ("SUNRPC: Use gssproxy upcall for server RPCGSS
authentication.")
- commit b88cf73d92 ("net: add missing entries to
Documentation/networking/00-INDEX")
* generic-hdlc.txt was added as generic_hdlc.txt
* spider_net.txt was added as spider-net.txt
- w1/master/mxc-w1 was added as mxc_w1 by commit a5fd9139f7 ("w1: add
1-wire master driver for i.MX27 / i.MX31")
- s390/zfcpdump.txt was added as zfcpdump by commit 6920c12a40
("[S390] Add Documentation/s390/00-INDEX.")
Signed-off-by: Henrik Austad <henrik@austad.us>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [rcu bits]
Acked-by: Rob Landley <rob@landley.net>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Mark Brown <broonie@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Len Brown <len.brown@intel.com>
Cc: James Bottomley <JBottomley@parallels.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The following files moved files out of Documentation/vm/
c6dd897f ("mm: move page-types.c from Documentation to tools/vm")
f0f57b2b ("move hugepage test examples to tools/testing/selftests/vm)
Remove these files from vm/00-INDEX.
The following commits added new files do Documentation/vm/
4fe4746a ("mm/fs: cleancache documentation") added vm/cleancache.txt
d65bfacb ("mm: highmem documentation") added vm/highmem.txt
1c9bf22c ("thp: transparent hugepage support documentation") added
vm/transhuge.txt
0f8975ec ("mm: soft-dirty bits for user memory changes tracking")
61b0d760 ("zswap: add documentation")
27c6aec2 ("mm: frontswap: config and doc files")
Add the missing documentation-files with a short description to 00-INDEX
Signed-off-by: Henrik Austad <henrik@austad.us>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
slabinfo.c has been moved from Documentaion/vm/ to
tools/slub/ by commit:0d24db337e6d81c0c620ab65cc6947bd6553f742
Update the slub.txt doc to reflect this change too.
Signed-off-by: Jason Liu <jason.hui@linaro.org>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Documentation/vm/:
Expose example and tool source files in the Documentation/ directory in
their own files instead of being buried (almost hidden) in readme/txt files.
This should help to prevent bitrot.
This will make them more visible/usable to users who may need
to use them, to developers who may need to test with them, and
to anyone who would fix/update them if they were more visible.
Also, if any of these possibly should not be in the kernel tree at
all, it will be clearer that they are here and we can discuss if
they should be removed.
Also build the recently-added map_hugetlb.c.
Make several functions static to prevent linker warnings.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Eric B Munson <ebmunson@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add an example of how to use the MAP_HUGETLB flag to the vm documentation
directory and a reference to the example in hugetlbpage.txt.
Signed-off-by: Eric B Munson <ebmunson@us.ibm.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add Documentation/vm/ksm.txt: how to use the Kernel Samepage Merging feature
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I'm sure everyone knows this, but I didn't, so I googled it, and found a
nice explanation from Linus. Might be worth sticking in Documentation.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Looks like the 00-INDEX file lost its parent directory in -rc6-mm1.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Vladimir Davydov
Henrik Austad
Jason Liu
Randy Dunlap
Eric B Munson
Hugh Dickins
Michael Ellerman
David Rientjes