From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752602AbaAXSxx (ORCPT ); Fri, 24 Jan 2014 13:53:53 -0500 Received: from merlin.infradead.org ([205.233.59.134]:47786 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751939AbaAXSxv (ORCPT ); Fri, 24 Jan 2014 13:53:51 -0500 Message-ID: <52E2B6BB.5040806@infradead.org> Date: Fri, 24 Jan 2014 10:53:47 -0800 From: Randy Dunlap User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: Aaron Tomlin , 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 Subject: Re: [PATCH] mm: Document improved handling of swappiness==0 References: <1390576408-16673-1-git-send-email-atomlin@redhat.com> In-Reply-To: <1390576408-16673-1-git-send-email-atomlin@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/24/2014 07:13 AM, Aaron Tomlin wrote: > 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 drop the comma ^ > +than the high water mark in a zone. > > The default value is 60. > > -- ~Randy