From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759614AbZDOLam (ORCPT ); Wed, 15 Apr 2009 07:30:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753723AbZDOLad (ORCPT ); Wed, 15 Apr 2009 07:30:33 -0400 Received: from brick.kernel.dk ([93.163.65.50]:50725 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753172AbZDOLac (ORCPT ); Wed, 15 Apr 2009 07:30:32 -0400 Date: Wed, 15 Apr 2009 13:30:31 +0200 From: Jens Axboe To: Jeff Moyer Cc: "Zhang, Yanmin" , LKML Subject: Re: tiobench read 50% regression with 2.6.30-rc1 Message-ID: <20090415113031.GY5178@kernel.dk> References: <1239265763.2567.769.camel@ymzhang> <20090409095706.GD5178@kernel.dk> <1239330541.2567.779.camel@ymzhang> <20090414121431.GH5178@kernel.dk> <20090415062649.GO5178@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 15 2009, Jeff Moyer wrote: > Jens Axboe writes: > > > On Wed, Apr 15 2009, Jeff Moyer wrote: > >> I tested this using iozone to read a file from an NFS client. 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. I > >> included numbers for the deadline scheduler as well for comparison. > >> > >> v2.6.29 > >> > >> nfsd's | 1 | 2 | 4 | 8 > >> --------+---------------+-------+------ > >> cfq | 91356 | 66391 | 61942 | 51674 > >> deadline| 43207 | 67436 | 96289 | 107784 > >> > >> 2.6.30-rc1 > >> > >> nfsd's | 1 | 2 | 4 | 8 > >> --------+---------------+-------+------ > >> cfq | 43127 | 22354 | 20858 | 21179 > >> deadline| 43732 | 68059 | 76659 | 83231 > >> > >> 2.6.30-rc1 + cfq fix > >> > >> nfsd's | 1 | 2 | 4 | 8 > >> --------+-----------------+-------+------ > >> cfq | 114602 | 102280 | 43479 | 43160 > >> > >> As you can see, for 1 and 2 threads, the patch *really* helps out. We > >> still don't get back the performance for 4 and 8 nfsd threads, though. > >> It's interesting to note that the deadline scheduler regresses for 4 and > >> 8 threads, as well. I think we've still got some digging to do. > > > > Wow, that does indeed look pretty good! > > Please don't lose the later part of the message, which is that both CFQ > and deadline regress for 4 and 8 threads when moving from 2.6.29 to > 2.6.30-rc1! There have been way too many changes to keep track of in > this area recently, and I'd like to get some confidence that we > understand the performance implications of them. I'm definitely not, in fact pending patches should make it better! For the nfs case, I'm still a big proponent of explicitly getting the io context sharing in place, instead of adding code at the other end to try and fix things up. > >> I'll try the cfq close cooperator patches next. > > > > I have a pending update on the coop patch that isn't pushed out yet, I > > hope to have it finalized and tested later today. Hopefully, with that, > > we should be able to maintain > 100Mb/sec for 4 and 8 threads. > > OK, please let me know when and where this is available and I'll give it > a try. I sent you email about ~10 minutes ago or so about that very patch. -- Jens Axboe