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authorAaron Tomlin <atomlin@redhat.com>2014-01-29 14:05:38 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-29 16:22:39 -0800
commit8582cb96b0bfd6891766d8c30d759bf21aad3b4d (patch)
treee603a54867acf33e5424d71f34e891b8dbb4e1bf /Documentation
parent0368dfd01ae3b7647ef9b2f0525fdefd5e0d28e1 (diff)
mm: document improved handling of swappiness==0
Prior to commit fe35004fbf9e ("mm: avoid swapping out with swappiness==0") setting swappiness to 0, reclaim code could still evict recently used user anonymous memory to swap even though there is a significant amount of RAM used for page cache. The behaviour of setting swappiness to 0 has since changed. When set, the reclaim code does not initiate swap until the amount of free pages and file-backed pages, is less than the high water mark in a zone. Let's update the documentation to reflect this. [akpm@linux-foundation.org: remove comma, per Randy] Signed-off-by: Aaron Tomlin <atomlin@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Bryn M. Reeves <bmr@redhat.com> Cc: Satoru Moriya <satoru.moriya@hds.com> Cc: Randy Dunlap <rdunlap@infradead.org> 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/sysctl/vm.txt4
1 files changed, 3 insertions, 1 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 9f5481bdc5a4..d614a9b6a280 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -696,7 +696,9 @@ swappiness
This control is used to define how aggressive the kernel will swap
memory pages. Higher values will increase agressiveness, lower values
-decrease the amount of swap.
+decrease the amount of swap. A value of 0 instructs the kernel not to
+initiate swap until the amount of free and file-backed pages is less
+than the high water mark in a zone.
The default value is 60.