From 8582cb96b0bfd6891766d8c30d759bf21aad3b4d Mon Sep 17 00:00:00 2001 From: Aaron Tomlin Date: Wed, 29 Jan 2014 14:05:38 -0800 Subject: 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 Acked-by: Rik van Riel Acked-by: Bryn M. Reeves Cc: Satoru Moriya Cc: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/sysctl/vm.txt | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 9f5481bdc5a..d614a9b6a28 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. -- cgit v1.2.3