From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261401AbULHXMk (ORCPT ); Wed, 8 Dec 2004 18:12:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261402AbULHXMk (ORCPT ); Wed, 8 Dec 2004 18:12:40 -0500 Received: from mail08.syd.optusnet.com.au ([211.29.132.189]:18904 "EHLO mail08.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S261401AbULHXMe (ORCPT ); Wed, 8 Dec 2004 18:12:34 -0500 References: <41B767CC.8000109@dif.dk> Message-ID: X-Mailer: http://www.courier-mta.org/cone/ From: Con Kolivas To: Jesper Juhl Cc: Bill Davidsen , linux-kernel@vger.kernel.org Subject: Re: Limiting program swap Date: Thu, 09 Dec 2004 10:12:20 +1100 Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset="US-ASCII" Content-Disposition: inline Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jesper Juhl writes: > Bill Davidsen wrote: >> I have several machine of various memory sizes which suffer from really >> poor performance when doing backups. This appears to be because all the >> programs other than the backup quickly get swapped to make room for i/o >> buffers. >> >> Is there some standard portable way to prevent this, either by reserving >> some memory for programs which will not get swapped regardless of i/o >> pressure, or alternatively limiting the total memory used for i/o >> buffers, dcache, and similar things? >> > > I'm wondering if turning the /proc/sys/vm/swappiness knob would help, > but I'll honestly admit that I don't know. No, there comes a point where the vm pressure overrides the value of swappiness and we start swapping. It is better in 2.6.7 and before with issues yet to be resolved in the latest mainline trees. My tree (-ck) has a slightly different tuning and a hard maplimit option for just such a reason but are unlikely to be of interest to the mainline maintainers so I've never promoted them. Cheers, Con