Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935742AbZLHAH6 (ORCPT ); Mon, 7 Dec 2009 19:07:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S935551AbZLHAH4 (ORCPT ); Mon, 7 Dec 2009 19:07:56 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35509 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935337AbZLHAHv (ORCPT ); Mon, 7 Dec 2009 19:07:51 -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> 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: Mon, 07 Dec 2009 19:07:51 -0500 In-Reply-To: <4e5e476b0912060245x4d64300hb9689243bd712f2c@mail.gmail.com> (Corrado Zoccolo's message of "Sun, 6 Dec 2009 11:45:16 +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=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5822 Lines: 98 Corrado Zoccolo writes: > Hi Jeff, I remember you saw large performance drop on your SAN for > sequential writes with low_latency=1. Can you test if Shaohua's and > this patch fix allow to recover some bandwidth? I think that enabling > the queue depth ramp up only if a sync request was delayed should > disable it for fast hardware like yours, so you should not be seeing > the slowdown any more. Average of 10 runs. Low latency set to 0: 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 90.08 94.51% 51.316 10268.25 0.00000 0.00000 95 2.6.32 8192 65536 16 99.36 199.8% 89.248 13883.81 0.00000 0.00000 50 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 81.16 85.90% 45.672 5963.19 0.00000 0.00000 94 2.6.32 8192 65536 16 116.32 230.3% 58.371 6098.36 0.00000 0.00000 51 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 8 112.17 1085.% 42.623 17114.54 0.00152 0.00000 10 2.6.32 8192 65536 16 111.26 2117.% 84.964 26480.60 0.03202 0.00000 5 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 8 162.48 887.1% 6.106 313.54 0.00000 0.00000 18 2.6.32 8192 65536 16 156.38 1767.% 14.077 1254.62 0.00000 0.00000 9 Average of 10 runs. Low latency set to 1: 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 92.23 100.1% 52.119 6920.18 0.00000 0.00000 92 2.6.32 8192 65536 16 97.88 217.0% 99.691 7453.18 0.00000 0.00000 45 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 98.70 107.5% 42.994 3409.08 0.00000 0.00000 92 2.6.32 8192 65536 16 140.41 323.9% 59.616 4525.46 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 8 112.33 1076.% 42.617 17072.28 0.00076 0.00000 10 2.6.32 8192 65536 16 111.84 2097.% 85.156 28221.77 0.02976 0.00000 5 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 8 159.33 870.5% 6.469 765.50 0.00000 0.00000 18 2.6.32 8192 65536 16 141.60 1632.% 15.364 2337.57 0.00000 0.00000 9 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/