Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754632AbZLRPcT (ORCPT ); Fri, 18 Dec 2009 10:32:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754362AbZLRPcR (ORCPT ); Fri, 18 Dec 2009 10:32:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45857 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753961AbZLRPcN convert rfc822-to-8bit (ORCPT ); Fri, 18 Dec 2009 10:32:13 -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, 18 Dec 2009 10:32:04 -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: 6560 Lines: 115 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. > if you have time, can you also re-run the test changing: > iosched/fifo_expire_async to 8 ? > I hope that reducing the expire_async, will make cfq quicker at switching > between the different threads, allowing more parallelism for seq > writers on your hw. > If this is the case, I think I can try to estimate the > fifo_expire_async in the autotuning patch. Sorry this took so long. I've been rather busy of late. Cheers, Jeff low_latency=1, fifo_expire_async=8 Unit information ================ File size = megabytes Blk Size = bytes Rate = megabytes per second CPU% = percentage of CPU used during the test Latency = milliseconds Lat% = percent of requests that took longer than X seconds CPU Eff = Rate divided by CPU% - throughput per cpu load Sequential 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 88.39 89.74% 16.388 2032.62 0.00000 0.00000 98 2.6.32 8192 65536 16 90.77 185.3% 32.213 2175.99 0.00000 0.00000 49 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 19.62 25.74% 71.827 3397.26 0.00000 0.00000 76 2.6.32 8192 65536 16 23.82 55.01% 103.361 4075.53 0.00000 0.00000 43 Sequential 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 8 108.28 1007.% 12.984 5643.55 0.00076 0.00000 11 2.6.32 8192 65536 16 112.40 2014.% 25.430 8592.98 0.00839 0.00000 6 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 63.94 337.7% 22.885 6047.22 0.00076 0.00000 19 2.6.32 8192 65536 16 61.94 662.5% 46.997 12759.69 0.15411 0.00000 9 low_latency=0, fifo_expire_async=8 Unit information ================ File size = megabytes Blk Size = bytes Rate = megabytes per second CPU% = percentage of CPU used during the test Latency = milliseconds Lat% = percent of requests that took longer than X seconds CPU Eff = Rate divided by CPU% - throughput per cpu load Sequential 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 89.13 88.30% 15.872 3101.39 0.00000 0.00000 101 2.6.32 8192 65536 16 86.78 161.7% 30.794 4909.02 0.00000 0.00000 54 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 20.21 26.64% 69.863 4285.42 0.00000 0.00000 76 2.6.32 8192 65536 16 20.10 52.75% 139.761 5986.94 0.00076 0.00000 38 Sequential 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 8 108.74 1020.% 13.070 5331.78 0.00076 0.00000 11 2.6.32 8192 65536 16 112.18 2020.% 25.559 7903.16 0.00992 0.00000 6 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 64.53 337.8% 22.671 5388.77 0.00000 0.00000 19 2.6.32 8192 65536 16 61.75 668.9% 47.265 13271.37 0.12894 0.00000 9 -- 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/