From 72c6f804ff1252217e799b0a847e049effef9bfc Mon Sep 17 00:00:00 2001 From: Aaron Tomlin Date: Wed, 29 Jan 2014 14:05:38 -0800 Subject: [PATCH] mm: document improved handling of swappiness==0 Prior to commit 9d22a99b3e66 ("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(-) diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 9f5481bdc5a43..d614a9b6a2804 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. -- 2.39.5