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authorAndrea Righi <righi.andrea@gmail.com>2008-10-18 23:27:13 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-20 11:52:32 -0400
commit7a6560e02556b6f0a798c247f3a557c523d9701b (patch)
tree7c1ded3e016e8604deb0cfb3b2d85389a8ae106e /Documentation/filesystems
parent9f1b16a51ea7180eca8a0d76a6bd587385a30757 (diff)
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/filesystems')
-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.
1384dirty_background_ratio 1384dirty_background_ratio
1385---------------------- 1385----------------------
1386 1386
1387Contains, as a percentage of total system memory, the number of pages at which 1387Contains, as a percentage of the dirtyable system memory (free pages + mapped
1388the pdflush background writeback daemon will start writing out dirty data. 1388pages + file cache, not including locked pages and HugePages), the number of
1389pages at which the pdflush background writeback daemon will start writing out
1390dirty data.
1389 1391
1390dirty_ratio 1392dirty_ratio
1391----------------- 1393-----------------
1392 1394
1393Contains, as a percentage of total system memory, the number of pages at which 1395Contains, as a percentage of the dirtyable system memory (free pages + mapped
1394a process which is generating disk writes will itself start writing out dirty 1396pages + file cache, not including locked pages and HugePages), the number of
1395data. 1397pages at which a process which is generating disk writes will itself start
1398writing out dirty data.
1396 1399
1397dirty_writeback_centisecs 1400dirty_writeback_centisecs
1398------------------------- 1401-------------------------