From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754669AbZEKNzW (ORCPT ); Mon, 11 May 2009 09:55:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753000AbZEKNzE (ORCPT ); Mon, 11 May 2009 09:55:04 -0400 Received: from mx2.redhat.com ([66.187.237.31]:33730 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752093AbZEKNzB (ORCPT ); Mon, 11 May 2009 09:55:01 -0400 From: Jeff Moyer To: Jens Axboe Cc: Andrew Morton , linux-kernel@vger.kernel.org, "Rafael J. Wysocki" Subject: Re: 2.6.30-rc deadline scheduler performance regression for iozone over NFS References: <20090508120119.8c93cfd7.akpm@linux-foundation.org> <20090511081415.GL4694@kernel.dk> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Mon, 11 May 2009 09:53:32 -0400 In-Reply-To: <20090511081415.GL4694@kernel.dk> (Jens Axboe's message of "Mon, 11 May 2009 10:14:15 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.60 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jens Axboe writes: > On Fri, May 08 2009, Andrew Morton wrote: >> On Thu, 23 Apr 2009 10:01:58 -0400 >> Jeff Moyer wrote: >> >> > Hi, >> > >> > I've been working on CFQ improvements for interleaved I/Os between >> > processes, and noticed a regression in performance when using the >> > deadline I/O scheduler. The test uses a server configured with a cciss >> > array and 1Gb/s ethernet. >> > >> > The iozone command line was: >> > iozone -s 2000000 -r 64 -f /mnt/test/testfile -i 1 -w >> > >> > The numbers in the nfsd's row represent the number of nfsd "threads". >> > These numbers (in MB/s) represent the average of 5 runs. >> > >> > v2.6.29 >> > >> > nfsd's | 1 | 2 | 4 | 8 >> > --------+---------------+-------+------ >> > deadline| 43207 | 67436 | 96289 | 107590 >> > >> > 2.6.30-rc1 >> > >> > nfsd's | 1 | 2 | 4 | 8 >> > --------+---------------+-------+------ >> > deadline| 43732 | 68059 | 76659 | 83231 >> > >> > 2.6.30-rc3.block-for-linus >> > >> > nfsd's | 1 | 2 | 4 | 8 >> > --------+---------------+-------+------ >> > deadline| 46102 | 71151 | 83120 | 82330 >> > >> > >> > Notice the drop for 4 and 8 threads. It may be worth noting that the >> > default number of NFSD threads is 8. >> > >> >> I guess we should ask Rafael to add this to the post-2.6.29 regression >> list. > > I agree. It'd be nice to bisect this one down, I'm guessing some mm > change has caused this writeout regression. It's not writeout, it's a read test. Cheers, Jeff