Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262197AbTFKPBb (ORCPT ); Wed, 11 Jun 2003 11:01:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262192AbTFKPBb (ORCPT ); Wed, 11 Jun 2003 11:01:31 -0400 Received: from e35.co.us.ibm.com ([32.97.110.133]:17886 "EHLO e35.co.us.ibm.com") by vger.kernel.org with ESMTP id S262164AbTFKPB2 (ORCPT ); Wed, 11 Jun 2003 11:01:28 -0400 Message-ID: <3EE747BD.6010408@austin.ibm.com> Date: Wed, 11 Jun 2003 10:16:13 -0500 From: Steven Pratt User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.2) Gecko/20021120 Netscape/7.01 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Nick Piggin CC: linux-kernel , Andrew Morton Subject: Re: 2.5.70-mm2 causes performance drop of random read O_DIRECT References: <3EE5190D.3070401@austin.ibm.com> <3EE522AA.7020200@cyberone.com.au> <3EE5E5AA.6020901@austin.ibm.com> <3EE67F38.9030702@cyberone.com.au> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1450 Lines: 41 Nick Piggin wrote: > Steven Pratt wrote: > >> Nick Piggin wrote: >> >>> Steven Pratt wrote: >>> >>>> Starting in 2.5.70-mm2 and continuing in the mm tree, there is a >>>> significant degrade in random read for block devices using >>>> O_DIRECT. The drop occurs for all block sizes and ranges from >>>> 30%-40. CPU usage is also lower although it may already be so low >>>> as to be irrelavent. >>> >>> Hi Steven, this is quite likely to be an io scheduler problem. >>> Is your test program rawread v2.1.5? >> >> This test was actually using 2.1.4, but the only difference in the >> 2.1.5 version is a fix for the test label array for the aio versions >> of the test. No functional change, just fixed the outputed test >> description. >> >>> What is the command line you are using to invoke the program? >> >> rawread -t6 -p8 -m1 -d2 -s4096 -n65536 -l1 -z -x >> >> Which you can find if you follow either results link and look in the >> benchmark directory where all raw benchmark out put is stored. > > OK thanks, I can now reproduce this! I'll work on it. Looks like Andrew beat you to it. Both 2.5.70-mm7 and mm8 are back up to the previous performance levels for random reads. Steve - 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/