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authorAndrea Righi <righi.andrea@gmail.com>2008-10-18 20:27:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-20 08:52:32 -0700
commit7a6560e02556b6f0a798c247f3a557c523d9701b (patch)
tree7c1ded3e016e8604deb0cfb3b2d85389a8ae106e /Documentation
parent9f1b16a51ea7180eca8a0d76a6bd587385a30757 (diff)
downloadlinux-linaro-stable-7a6560e02556b6f0a798c247f3a557c523d9701b.tar.gz
documentation: clarify dirty_ratio and dirty_background_ratio description
The current documentation of dirty_ratio and dirty_background_ratio is a bit misleading. In the documentation we say that they are "a percentage of total system memory", but the current page writeback policy, intead, is to apply the percentages to the dirtyable memory, that means free pages + reclaimable pages. Better to be more explicit to clarify this concept. Signed-off-by: Andrea Righi <righi.andrea@gmail.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> 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/filesystems/proc.txt13
1 files changed, 8 insertions, 5 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 02cb7faeed6b..bcceb99b81dd 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -1384,15 +1384,18 @@ causes the kernel to prefer to reclaim dentries and inodes.
dirty_background_ratio
----------------------
-Contains, as a percentage of total system memory, the number of pages at which
-the pdflush background writeback daemon will start writing out dirty data.
+Contains, as a percentage of the dirtyable system memory (free pages + mapped
+pages + file cache, not including locked pages and HugePages), the number of
+pages at which the pdflush background writeback daemon will start writing out
+dirty data.
dirty_ratio
-----------------
-Contains, as a percentage of total system memory, the number of pages at which
-a process which is generating disk writes will itself start writing out dirty
-data.
+Contains, as a percentage of the dirtyable system memory (free pages + mapped
+pages + file cache, not including locked pages and HugePages), the number of
+pages at which a process which is generating disk writes will itself start
+writing out dirty data.
dirty_writeback_centisecs
-------------------------