From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261389AbUFKIfM (ORCPT ); Fri, 11 Jun 2004 04:35:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261439AbUFKIfM (ORCPT ); Fri, 11 Jun 2004 04:35:12 -0400 Received: from smtp-send.myrealbox.com ([192.108.102.143]:32787 "EHLO smtp-send.myrealbox.com") by vger.kernel.org with ESMTP id S261389AbUFKIfF (ORCPT ); Fri, 11 Jun 2004 04:35:05 -0400 Subject: PROBLEM: Heavy iowait on 2.6 kernels From: Guy Van Sanden To: linux-kernel@vger.kernel.org Content-Type: text/plain Message-Id: <1086942905.10540.69.camel@cronos.home.vsb> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Fri, 11 Jun 2004 10:35:05 +0200 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I recently discovered why my new Gentoo server slows to a crawl on a intermediate load on the 2.6 kernel series. The reason seems to be an unusual amount of iowait. I can reproduce this on two systems, one with a KT400 and and one with Sis735 chipset. iostat -c 1 (or vmstat) while running something like bonnie produces iowaits of 99%. Any 2.6 kernel responds the same (regardless of the patchset), even vanilla. (2.6.5-mm, 2.6.6-mm, 2.6.6-vanilla and 2.6.5-gentoo-r1). Any 2.4-series kernel is fine. This is a sample iostat output -- avg-cpu: %user %nice %sys %iowait %idle 26.73 0.00 10.89 62.38 0.00 avg-cpu: %user %nice %sys %iowait %idle 0.00 0.00 13.00 87.00 0.00 avg-cpu: %user %nice %sys %iowait %idle 1.01 0.00 16.16 82.83 0.00 avg-cpu: %user %nice %sys %iowait %idle 0.00 0.00 11.88 88.12 0.00 avg-cpu: %user %nice %sys %iowait %idle 0.00 0.00 1.01 98.99 0.00 avg-cpu: %user %nice %sys %iowait %idle 0.99 0.00 2.97 96.04 0.00 -- -- ______________________________________________________________________ Guy Van Sanden http://unixmafia.port5.com Registered Linux user #249404 - September 1997 ______________________________________________________________________