From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 16 Sep 2001 15:38:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 16 Sep 2001 15:38:34 -0400 Received: from neon-gw-l3.transmeta.com ([63.209.4.196]:42757 "EHLO neon-gw.transmeta.com") by vger.kernel.org with ESMTP id ; Sun, 16 Sep 2001 15:38:25 -0400 To: linux-kernel@vger.kernel.org From: torvalds@transmeta.com (Linus Torvalds) Subject: Re: broken VM in 2.4.10-pre9 Date: Sun, 16 Sep 2001 19:37:31 +0000 (UTC) Organization: Transmeta Corporation Message-ID: <9o2v1r$85g$1@penguin.transmeta.com> In-Reply-To: <9o1dev$23l$1@penguin.transmeta.com> <1000722338.14005.0.camel@x153.internalnet> X-Trace: palladium.transmeta.com 1000669100 4710 127.0.0.1 (16 Sep 2001 19:38:20 GMT) X-Complaints-To: news@transmeta.com NNTP-Posting-Date: 16 Sep 2001 19:38:20 GMT Cache-Post-Path: palladium.transmeta.com!unknown@penguin.transmeta.com X-Cache: nntpcache 2.4.0b5 (see http://www.nntpcache.org/) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In article <1000722338.14005.0.camel@x153.internalnet>, Tonu Samuel wrote: > >Problem still exists and persists. Not long time ago man from Yahoo >described well case when change from 2.2.19 to 2.4.x caused performance >problems. On 2.2.19 everything ran fine. They have MySQL running+did >backups from disk. After upgrade to 2.4.x MySQL performance felt down on >backup time. They investigated stuff and found that MySQL daemon gets >swapped out in the middle of usage to make room for buffers. Note that if you're using a raw device backup strategy (ie "e2dump" or similar), that is expected: 2.4.x up until about 2.4.7 gave _much_ too much preference to the buffer cache. That should actually have been fixed in 2.4.8. We used to mark buffer pages much too active. > In summary: >this made both sql and backup double slow. Even increasing memory from >1G->2G didn't helped. Finally they disabled swap at all and problem >lost. You just hid the problem - by disabling swap the buffer cache couldn't grow without bounds any more, and the proper buffer cache shrinking couldn't happen. Try 2.4.8 or later. >If you do not want to change it back as it was in 2.2.x then would be >good if this is tunable somehow. Tuning for bugs? What do you want to happen? You want to have an interface like echo 0 > /proc/bugs/mm that makes mm bugs go away? Linus