From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261701AbVGUJA1 (ORCPT ); Thu, 21 Jul 2005 05:00:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261702AbVGUJA1 (ORCPT ); Thu, 21 Jul 2005 05:00:27 -0400 Received: from uucp.cistron.nl ([62.216.30.38]:20957 "EHLO ncc1701.cistron.net") by vger.kernel.org with ESMTP id S261701AbVGUJAZ (ORCPT ); Thu, 21 Jul 2005 05:00:25 -0400 From: "Miquel van Smoorenburg" Subject: Re: Multi-threaded IO performance regression on 2.6 kernel? Date: Thu, 21 Jul 2005 09:00:23 +0000 (UTC) Organization: Cistron Message-ID: References: <1784BBD8D1F15B4C9FB0F09F0A939F9001A3E463@SZEXMTA4.amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Trace: ncc1701.cistron.net 1121936423 10444 194.109.0.112 (21 Jul 2005 09:00:23 GMT) X-Complaints-To: abuse@cistron.nl X-Newsreader: trn 4.0-test76 (Apr 2, 2001) Originator: mikevs@cistron.nl (Miquel van Smoorenburg) To: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In article <1784BBD8D1F15B4C9FB0F09F0A939F9001A3E463@SZEXMTA4.amd.com>, Xie, Bill wrote: >All, > >I am testing the multi-threaded IO performance on Opteron servers. > >I use dd as the test tools. The single dd can reach 60MBps for single disk. > >on 2.6.5 kernel, If dd numbers exceed the CPU numbers, vmstat bi reduced >to 20MBps. > >on 2.4.21 kernel, multi-threaded IO performance works fine, even I run >40 dd command at same time. > >Does anybody experienced similar issue also? First, use a more recent kernel, 2.6.11.x or 2.6.12.x. Then try if changing the I/O scheduler (/sys/block/sda/queue/scheduler) to deadline or cfq makes a difference. I'm using 2.6.11.x and the cfq scheduler on most servers right now. Mike.