Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751300AbVIRERx (ORCPT ); Sun, 18 Sep 2005 00:17:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751305AbVIRERx (ORCPT ); Sun, 18 Sep 2005 00:17:53 -0400 Received: from dial169-234.awalnet.net ([213.184.169.234]:54020 "EHLO raad.intranet") by vger.kernel.org with ESMTP id S1751300AbVIRERx (ORCPT ); Sun, 18 Sep 2005 00:17:53 -0400 From: Al Boldi To: Willy Tarreau Subject: Re: Eradic disk access during reads Date: Sun, 18 Sep 2005 07:16:46 +0300 User-Agent: KMail/1.5 Cc: linux-kernel@vger.kernel.org References: <200509170717.03439.a1426z@gawab.com> <200509171323.53054.a1426z@gawab.com> <20050917184643.GA1313@alpha.home.local> In-Reply-To: <20050917184643.GA1313@alpha.home.local> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200509180716.46978.a1426z@gawab.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 908 Lines: 27 Willy Tarreau wrote: > On Sat, Sep 17, 2005 at 01:32:53PM +0300, Al Boldi wrote: > > Willy Tarreau wrote: > > > On Sat, Sep 17, 2005 at 07:26:11AM +0300, Al Boldi wrote: > > > > Monitoring disk access using gkrellm, I noticed that a command like > > > > > > > > cat /dev/hda > /dev/null > > > > > > > > shows eradic disk reads ranging from 0 to 80MB/s on an otherwise > > > > idle system. New synonym: eradic=erratic :) > Denis' tool seems clearly more suited to analyse your problem. The problem seems to be a multi-access collision in the queue, which forces a ~50% reduction of thruput, which recovers with another multi-access collision. Maybe?! -- Al - 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/