Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261169AbUDPRey (ORCPT ); Fri, 16 Apr 2004 13:34:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261875AbUDPRey (ORCPT ); Fri, 16 Apr 2004 13:34:54 -0400 Received: from rwcrmhc12.comcast.net ([216.148.227.85]:9147 "EHLO rwcrmhc12.comcast.net") by vger.kernel.org with ESMTP id S261169AbUDPRex (ORCPT ); Fri, 16 Apr 2004 13:34:53 -0400 Subject: Re: Huge iowait on 2.6.4 - not on 2.4.20 ! From: Albert Cahalan To: linux-kernel mailing list Cc: alandpearson@yahoo.com Content-Type: text/plain Organization: Message-Id: <1082128366.849.60.camel@cube> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.4 Date: 16 Apr 2004 11:12:47 -0400 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1035 Lines: 34 alan pearson writes: > On 2.6 the iowait jumps to around 70%, while 2.4 on > both tests it is firmly zero. The 2.4 kernel lumps iowait into idle, so you won't see iowait on a 2.4 kernel. > On disk read, I'm loosing 30 Mb/sec of bandwidth PER > DISK, compared to 2.4.20. > I've tried using both the deadline and as ioschedulers > but no difference. > > > Under real conditions (ie our application running > which reads from all the disks simultaneously) on > 2.6.4, the system performance is around 1/3 of 2.4.20) > > Summary MB/Sec : > > dd if=x dd if=/dev/zero > 2.4 64 35.6 > 2.6 30.34 35.9 Well, that looks serious, but unfortunately you can't tell what the iowait was on the 2.4 kernel. Only the 2.6 kernel provides this information. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/