Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758560AbZLKRus (ORCPT ); Fri, 11 Dec 2009 12:50:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753632AbZLKRum (ORCPT ); Fri, 11 Dec 2009 12:50:42 -0500 Received: from mx1.redhat.com ([209.132.183.28]:3395 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753053AbZLKRul convert rfc822-to-8bit (ORCPT ); Fri, 11 Dec 2009 12:50:41 -0500 From: Jeff Moyer To: Corrado Zoccolo Cc: Linux-Kernel , Jens Axboe , Vivek Goyal Subject: Re: [PATCH] cfq-iosched: reduce write depth only if sync was delayed References: <4b1a3d84.0d0db80a.39d0.ffff814a@mx.google.com> <4e5e476b0912050313k280caa8bjf7c2cf1c5d19c88c@mail.gmail.com> <4e5e476b0912060245x4d64300hb9689243bd712f2c@mail.gmail.com> <4e5e476b0912081243ra071947if9a3edae77fb3861@mail.gmail.com> <4e5e476b0912110915u209b8923m359d9147cc229fea@mail.gmail.com> 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: Fri, 11 Dec 2009 12:50:42 -0500 In-Reply-To: <4e5e476b0912110915u209b8923m359d9147cc229fea@mail.gmail.com> (Corrado Zoccolo's message of "Fri, 11 Dec 2009 18:15:20 +0100") Message-ID: User-Agent: Gnus/5.110011 (No Gnus v0.11) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3362 Lines: 64 Corrado Zoccolo writes: > Hi Jeff, > On Wed, Dec 9, 2009 at 7:09 PM, Jeff Moyer wrote: >> Corrado Zoccolo writes: >> >>> The numbers look good. Now, there is no penalty in having low_latency >>> set for sequential writes, and just a small penalty for random ones. >>> The fact that random reads are faster with low_latency set is interesting. >>> Is the test is running with your patched tiobench (so that the number >>> of random operations is comparable with sequential ones)? >> >> No, I forgot all about that.  The number of random operations defaults >> to 4000, which is pretty low.  I'll re-run the tests with a number >> comparable to the sequential runs.  Sorry about that. >> > N.P. low_latency=1 Random Reads File Blk Num Avg Maximum Lat% Lat% CPU Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff ---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- ----- 2.6.32 8192 65536 8 19.35 26.10% 74.639 3278.74 0.00000 0.00000 74 2.6.32 8192 65536 16 20.40 53.07% 135.695 3705.55 0.00000 0.00000 38 Random Writes File Blk Num Avg Maximum Lat% Lat% CPU Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff ---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- ----- 2.6.32 8192 65536 8 64.64 342.2% 22.708 5960.22 0.00153 0.00000 19 2.6.32 8192 65536 16 61.19 663.7% 47.648 11294.56 0.16098 0.00000 9 low_latency=0 Random Reads File Blk Num Avg Maximum Lat% Lat% CPU Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff ---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- ----- 2.6.32 8192 65536 8 19.71 25.32% 70.891 4340.92 0.00000 0.00000 78 2.6.32 8192 65536 16 22.67 58.94% 121.669 6180.49 0.00229 0.00000 38 Random Writes File Blk Num Avg Maximum Lat% Lat% CPU Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff ---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- ----- 2.6.32 8192 65536 8 64.69 339.5% 22.651 6770.99 0.00152 0.00000 19 2.6.32 8192 65536 16 61.94 663.0% 46.962 10719.13 0.12741 0.00000 9 > if you have time, can you also re-run the test changing: > iosched/fifo_expire_async to 8 ? Sure. Cheers, Jeff -- 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/