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pagemap clear_refs: modify to specify anon or mapped vma clearing

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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>
This commit is contained in:
Moussa A. Ba
2009-09-21 17:02:29 -07:00
committed by Linus Torvalds
parent 7103ad323b
commit 398499d5f3
2 changed files with 37 additions and 4 deletions
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13
Documentation/filesystems/proc.txt
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@@ -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
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