From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759703AbZDOMBE (ORCPT ); Wed, 15 Apr 2009 08:01:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758789AbZDOMAu (ORCPT ); Wed, 15 Apr 2009 08:00:50 -0400 Received: from mx2.redhat.com ([66.187.237.31]:59541 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757514AbZDOMAt (ORCPT ); Wed, 15 Apr 2009 08:00:49 -0400 From: Jeff Moyer To: Jens Axboe Cc: "Zhang\, Yanmin" , LKML Subject: Re: tiobench read 50% regression with 2.6.30-rc1 References: <1239265763.2567.769.camel@ymzhang> <20090409095706.GD5178@kernel.dk> <1239330541.2567.779.camel@ymzhang> <20090414121431.GH5178@kernel.dk> <20090415062649.GO5178@kernel.dk> <20090415113031.GY5178@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: Wed, 15 Apr 2009 08:00:44 -0400 In-Reply-To: <20090415113031.GY5178@kernel.dk> (Jens Axboe's message of "Wed, 15 Apr 2009 13:30:31 +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 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 OK, I'll look through the changelog of your for-linus branch. > 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. OK, I have an ugly patch that wires that up. I guess it's time to clean that up and test it. >> >> 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. Yep, got it. Thanks! -Jeff