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| author | Moussa A. Ba <moussa.a.ba@gmail.com> | 2009-09-21 17:02:29 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-22 07:17:33 -0700 |
| commit | 398499d5f3613c47f2143b8c54a04efb5d7a6da9 (patch) | |
| tree | 0b337ca1d0e20caa2295c159d5c0deadf362e4a0 /Documentation/filesystems/proc.txt | |
| parent | 7103ad323b1ae32bedc3267402117e2f8b45e48d (diff) | |
| download | lwn-398499d5f3613c47f2143b8c54a04efb5d7a6da9.tar.gz lwn-398499d5f3613c47f2143b8c54a04efb5d7a6da9.zip | |
pagemap clear_refs: modify to specify anon or mapped vma clearing
The patch makes the clear_refs more versatile in adding the option to
select anonymous pages or file backed pages for clearing. This addition
has a measurable impact on user space application performance as it
decreases the number of pagewalks in scenarios where one is only
interested in a specific type of page (anonymous or file mapped).
The patch adds anonymous and file backed filters to the clear_refs interface.
echo 1 > /proc/PID/clear_refs resets the bits on all pages
echo 2 > /proc/PID/clear_refs resets the bits on anonymous pages only
echo 3 > /proc/PID/clear_refs resets the bits on file backed pages only
Any other value is ignored
Signed-off-by: Moussa A. Ba <moussa.a.ba@gmail.com>
Signed-off-by: Jared E. Hulbert <jaredeh@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/filesystems/proc.txt')
| -rw-r--r-- | Documentation/filesystems/proc.txt | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 1c96cb6c7972..ae7f8bb1b7bc 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -375,6 +375,19 @@ of memory currently marked as referenced or accessed. This file is only present if the CONFIG_MMU kernel configuration option is enabled. +The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG +bits on both physical and virtual pages associated with a process. +To clear the bits for all the pages associated with the process + > echo 1 > /proc/PID/clear_refs + +To clear the bits for the anonymous pages associated with the process + > echo 2 > /proc/PID/clear_refs + +To clear the bits for the file mapped pages associated with the process + > echo 3 > /proc/PID/clear_refs +Any other value written to /proc/PID/clear_refs will have no effect. + + 1.2 Kernel data --------------- |