From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752852AbaAXPOM (ORCPT ); Fri, 24 Jan 2014 10:14:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41421 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752477AbaAXPOK (ORCPT ); Fri, 24 Jan 2014 10:14:10 -0500 From: Aaron Tomlin To: mingo@kernel.org Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, rientjes@google.com, mingo@redhat.com, oleg@redhat.com, riel@redhat.com, bmr@redhat.com, akpm@linux-foundation.org, atomlin@redhat.com Subject: [PATCH] mm: Document improved handling of swappiness==0 Date: Fri, 24 Jan 2014 15:13:28 +0000 Message-Id: <1390576408-16673-1-git-send-email-atomlin@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Prior to upstream commit fe35004f ("[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. Signed-off-by: Aaron Tomlin Acked-by: Rik van Riel Acked-by: Bryn M. Reeves --- 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 9f5481b..38388ee 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. -- 1.8.4.2