From: Aaron Tomlin Date: Wed, 29 Jan 2014 22:05:38 +0000 (-0800) Subject: mm: document improved handling of swappiness==0 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=8582cb96b0bfd6891766d8c30d759bf21aad3b4d;p=linux-beck.git 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 --- 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.