From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756225AbYE2Lg6 (ORCPT ); Thu, 29 May 2008 07:36:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751845AbYE2Lgo (ORCPT ); Thu, 29 May 2008 07:36:44 -0400 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:39335 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751834AbYE2Lgm (ORCPT ); Thu, 29 May 2008 07:36:42 -0400 Date: Thu, 29 May 2008 12:22:23 +0100 From: Alan Cox To: Bill Davidsen Cc: Jens =?UTF-8?B?QsOkY2ttYW4=?= , Justin Piszcz , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, xfs@oss.sgi.com Subject: Re: Performance Characteristics of All Linux RAIDs (mdadm/bonnie++) Message-ID: <20080529122223.462bf396@core> In-Reply-To: <483DE40D.8090608@tmr.com> References: <95711f160805280934y77ed7d91tec5aeb531bf8013c@mail.gmail.com> <20080528195752.0cdcbc6d@core> <483DE40D.8090608@tmr.com> X-Mailer: Claws Mail 3.3.1 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > I really don't think that's any part of the issue, the same memory and > bridge went 4-5x faster in other read cases. The truth is that the > raid-1 performance is really bad, and it's the code causing it AFAIK. If > you track the actual io it seems to read one drive at a time, in order, > without overlap. Make sure the readahead is set to be a fair bit over the stripe size if you are doing bulk data tests for a single file. (Or indeed in the real world for that specific case ;))