From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Thu, 29 May 2008 04:35:54 -0700 (PDT) Received: from cuda.sgi.com ([192.48.176.15]) by oss.sgi.com (8.12.11.20060308/8.12.11/SuSE Linux 0.7) with ESMTP id m4TBZkZ3001101 for ; Thu, 29 May 2008 04:35:49 -0700 Received: from lxorguk.ukuu.org.uk (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id EEAC11B98682 for ; Thu, 29 May 2008 04:36:38 -0700 (PDT) Received: from lxorguk.ukuu.org.uk (earthlight.etchedpixels.co.uk [81.2.110.250]) by cuda.sgi.com with ESMTP id mEzQk6t9bHGHA2p3 for ; Thu, 29 May 2008 04:36:38 -0700 (PDT) Date: Thu, 29 May 2008 12:22:23 +0100 From: Alan Cox 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> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs 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 > 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 ;))