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authorVladimir Davydov <vdavydov@parallels.com>2015-09-09 15:35:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-10 13:29:01 -0700
commitf074a8f49eb87cde95ac9d040ad5e7ea4f029738 (patch)
treec78d0a5386ee6d9db9de32c733df404e783088d5 /Documentation
parent33c3fc71c8cfa3cc3a98beaa901c069c177dc295 (diff)
proc: export idle flag via kpageflags
As noted by Minchan, a benefit of reading idle flag from /proc/kpageflags is that one can easily filter dirty and/or unevictable pages while estimating the size of unused memory. Note that idle flag read from /proc/kpageflags may be stale in case the page was accessed via a PTE, because it would be too costly to iterate over all page mappings on each /proc/kpageflags read to provide an up-to-date value. To make sure the flag is up-to-date one has to read /sys/kernel/mm/page_idle/bitmap first. 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>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/vm/pagemap.txt7
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/vm/pagemap.txt b/Documentation/vm/pagemap.txt
index ce294b0aace4..0e1e55588b59 100644
--- a/Documentation/vm/pagemap.txt
+++ b/Documentation/vm/pagemap.txt
@@ -70,6 +70,7 @@ There are four components to pagemap:
22. THP
23. BALLOON
24. ZERO_PAGE
+ 25. IDLE
* /proc/kpagecgroup. This file contains a 64-bit inode number of the
memory cgroup each page is charged to, indexed by PFN. Only available when
@@ -120,6 +121,12 @@ Short descriptions to the page flags:
24. ZERO_PAGE
zero page for pfn_zero or huge_zero page
+25. IDLE
+ page has not been accessed since it was marked idle (see
+ Documentation/vm/idle_page_tracking.txt). Note that this flag may be
+ stale in case the page was accessed via a PTE. To make sure the flag
+ is up-to-date one has to read /sys/kernel/mm/page_idle/bitmap first.
+
[IO related page flags]
1. ERROR IO error occurred
3. UPTODATE page has up-to-date data