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| author | Vladimir Davydov <vdavydov@parallels.com> | 2015-09-10 00:35:48 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-09-10 22:29:01 +0200 |
| commit | f074a8f49eb87cde95ac9d040ad5e7ea4f029738 (patch) | |
| tree | c78d0a5386ee6d9db9de32c733df404e783088d5 /Documentation | |
| parent | mm: introduce idle page tracking (diff) | |
| download | linux-f074a8f49eb87cde95ac9d040ad5e7ea4f029738.tar.xz linux-f074a8f49eb87cde95ac9d040ad5e7ea4f029738.zip | |
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.txt | 7 |
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 |