From f074a8f49eb87cde95ac9d040ad5e7ea4f029738 Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Wed, 9 Sep 2015 15:35:48 -0700 Subject: 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 Reviewed-by: Andres Lagar-Cavilla Cc: Minchan Kim Cc: Raghavendra K T Cc: Johannes Weiner Cc: Michal Hocko Cc: Greg Thelen Cc: Michel Lespinasse Cc: David Rientjes Cc: Pavel Emelyanov Cc: Cyrill Gorcunov Cc: Jonathan Corbet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/vm/pagemap.txt | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'Documentation') 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 -- cgit v1.2.3-59-g8ed1b