From 398499d5f3613c47f2143b8c54a04efb5d7a6da9 Mon Sep 17 00:00:00 2001 From: "Moussa A. Ba" Date: Mon, 21 Sep 2009 17:02:29 -0700 Subject: 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 Signed-off-by: Jared E. Hulbert Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/filesystems/proc.txt | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'Documentation') 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 --------------- -- cgit v1.2.3-59-g8ed1b