From: Andrea Righi Date: Sun, 19 Oct 2008 03:27:13 +0000 (-0700) Subject: documentation: clarify dirty_ratio and dirty_background_ratio description X-Git-Tag: v2.6.28-rc1~208 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=7a6560e02556b6f0a798c247f3a557c523d9701b;p=linux-2.6-omap-h63xx.git 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 Signed-off-by: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 02cb7faeed6..bcceb99b81d 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 -------------------------