Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755035AbZKCUR6 (ORCPT ); Tue, 3 Nov 2009 15:17:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754361AbZKCUR6 (ORCPT ); Tue, 3 Nov 2009 15:17:58 -0500 Received: from [95.166.99.235] ([95.166.99.235]:41001 "EHLO kernel.dk" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1754249AbZKCUR5 (ORCPT ); Tue, 3 Nov 2009 15:17:57 -0500 Date: Tue, 3 Nov 2009 21:18:02 +0100 From: Jens Axboe To: Corrado Zoccolo Cc: Linux-Kernel , Jeff Moyer Subject: Re: Fwd: [PATCH 0/5] cfq-iosched: improve latency for no-idle queues (v3) Message-ID: <20091103201802.GL8742@kernel.dk> References: <200910262243.41327.czoccolo@gmail.com> <4e5e476b0910271124r2cf9f9c0l83fdc59b50619202@mail.gmail.com> <4e5e476b0911030042q5963718aj5875c542e6f6cc40@mail.gmail.com> <4e5e476b0911030719m425c208cg311f44a91fad8342@mail.gmail.com> <4e5e476b0911031035l7caffcb7n36b6eddd399864e7@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4e5e476b0911031035l7caffcb7n36b6eddd399864e7@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2724 Lines: 68 On Tue, Nov 03 2009, Corrado Zoccolo wrote: > Hi Jens, > Jeff did some testing of this patchset on his NCQ-enabled SSD (the > 30GB OCZ Vertex). > The test suite contained various multiple competing workloads > scenarios, and was run on for-2.6.33 and cfq-2.6.33 branches. > > Max latencies were reduced in most cases, and we had also improvements > on bandwidth side in some scenarios, especially > for multiple random readers, either alone or competing with writes. > 2 random readers aggregate bw increased from 48356 to 74205 > and 4 random readers vs 1 seq writer: > * aggregate reader bw increased from 35242 to 56400 > * writer bandwidth increased from 33269 to 55127 > * maximum latency on read decreased from 535 to 324 > * maximum latency on writes decreased from 22243 to 1153 > It's a win on all measures. > The effect increasing the number of readers to 32 (latency_test_2.fio) > is even more visible (max read latency reduced from 3305 to 268, > aggregated read BW increased from 32894 to 164571). > > The only case where I see an increased max latency is for 2 random > readers vs 1 seq reader: > > for-2.6.33: > randomread.0: read_bw = 15,418K > randomread.1: read_bw = 15,399K > seqread: read_bw = 409K > 0: read_bw = 31226 > 0: read_lat_max = 11.589 > 0: read_lat_avg = 3.22366666666667 > > cfq-2.6.33: > randomread.0: read_bw = 10,065K > randomread.1: read_bw = 10,067K > seqread: read_bw = 101M > 0: read_bw = 121132 > 0: read_lat_max = 303 > 0: read_lat_avg = 0.282333333333333 > > but here the increased latency is paid back by a large increase in > sequential read BW (the max latency is, btw, experienced by the seq > reader, so I think it is a fair behaviour). > > Jeff observed that the for-2.6.33 numbers were worse than his baseline > runs, probably due to changed hw_tag detection. > My patchset is much less sensible to hw_tag on SSDs (since there are > much less situations in which it would idle), so my numbers are > unaffected. Thanks a lot for your testing. My testing on cfq-2.6.33 looks good too, so I pulled it into for-2.6.33 today. Since for-linus contains conflicting changes, can you and Jeff please double check that everything is still in order? The interesting bit here is the merge with for-2.6.33 and the coop limit from Shaohua Li. I did the straight forward merge, but we likely just need to drop that logic since the coop concept is radically different given that we merge and break queues in for-2.6.33. -- Jens Axboe -- 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/