Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756614AbYJMVWx (ORCPT ); Mon, 13 Oct 2008 17:22:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756086AbYJMVWk (ORCPT ); Mon, 13 Oct 2008 17:22:40 -0400 Received: from 1-1-4-20a.ras.sth.bostream.se ([82.182.72.90]:45427 "EHLO amd.kenjo.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756004AbYJMVWj (ORCPT ); Mon, 13 Oct 2008 17:22:39 -0400 Subject: Re: weird throughput on write to SATA disk From: kenneth johansson To: Grant Grundler Cc: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: References: <1223925629.3947.7.camel@duo> Content-Type: text/plain Date: Mon, 13 Oct 2008 23:22:36 +0200 Message-Id: <1223932956.3947.22.camel@duo> Mime-Version: 1.0 X-Mailer: Evolution 2.24.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 970 Lines: 27 On Mon, 2008-10-13 at 14:07 -0700, Grant Grundler wrote: > On Mon, Oct 13, 2008 at 12:19 PM, kenneth johansson wrote: > > When writing data to /dev/sdb (that is the whole disk and no filesystem) > > it starts out ok around 100MB/sec but soon end up doing considerably > > worse. For prolonged times lasting several minutes it hovers in the > > 20-30MB/sec. > > Is the application using "O_DIRECT"? no just open then write no fancy stuff > If not, could be issue with how VM writeback is (not) working. the access pattern is the simplest possible. Is there any knobs I could try to adjust. > Can you reproduce this using fio or even "dd"? > (See git://git.kernel.dk/fio) dd is having the same effect. -- 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/