Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753719AbXFXQ7V (ORCPT ); Sun, 24 Jun 2007 12:59:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751314AbXFXQ7M (ORCPT ); Sun, 24 Jun 2007 12:59:12 -0400 Received: from lucidpixels.com ([75.144.35.66]:33299 "EHLO lucidpixels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751000AbXFXQ7K (ORCPT ); Sun, 24 Jun 2007 12:59:10 -0400 Date: Sun, 24 Jun 2007 12:59:10 -0400 (EDT) From: Justin Piszcz X-X-Sender: jpiszcz@p34.internal.lan To: Michael Tokarev cc: "Dr. David Alan Gilbert" , Jeff Garzik , Carlo Wood , Tejun Heo , Manoj Kasichainula , linux-kernel@vger.kernel.org, IDE/ATA development list Subject: Re: SATA RAID5 speed drop of 100 MB/s In-Reply-To: <467E9356.1030200@msgid.tls.msk.ru> Message-ID: References: <20070620224847.GA5488@alinoe.com> <4679B2DE.9090903@garzik.org> <20070622214859.GC6970@alinoe.com> <467CC5C5.6040201@garzik.org> <20070623125316.GB26672@alinoe.com> <467DA1F5.2060306@garzik.org> <467E5C5E.6000706@msgid.tls.msk.ru> <20070624125957.GA28067@gallifrey> <467E9356.1030200@msgid.tls.msk.ru> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2200 Lines: 50 On Sun, 24 Jun 2007, Michael Tokarev wrote: > Justin Piszcz wrote: >> Don't forget about max_sectors_kb either (for all drives in the SW RAID5 >> array) >> >> max_sectors_kb = 8 >> $ dd if=/dev/zero of=file.out6 bs=1M count=10240 >> 10737418240 bytes (11 GB) copied, 55.4848 seconds, 194 MB/s >> >> max_sectors_kb = 128 >> 10737418240 bytes (11 GB) copied, 22.6298 seconds, 474 MB/s > > Well. You're comparing something different. Yes, this > thread is about linux software raid5 in the first place, > but I were commenting about [NT]CQ within a single drive. > > Overall, yes, the larger your reads/writes to the drive > becomes, the faster its linear performance is. Yet you > have to consider real workload instead of very synthetic > dd test. It may be good approcsimation of a streaming > video workload (when you feed a large video file over > network or something like that), but even with this, > you probably want to feed several files at once (different > files to different clients), so single-threaded test > here isn't very useful. IMHO anyway, and good for a > personal computer test. > > /mjt > - > To unsubscribe from this list: send the line "unsubscribe linux-ide" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Concerning NCQ/no NCQ, without NCQ I get an additional 15-50MB/s in speed per various bonnie++ tests. # Average of 3 runs with NCQ on for Quad Raptor 150 RAID 5 Software RAID: p34-ncq-on,7952M,43916.3,96.6667,151943,28.6667,75794.3,18.6667,48991.3,99,181687,24,558.033,0.333333,16:100000:16/64,867.667,9,29972.7,98.3333,2801.67,16,890.667,9.33333,27743,94.3333,2115.33,15.6667 # Average of 3 runs with NCQ off for Quad Raptor 150 RAID 5 Software RAID: p34-ncq-off,7952M,42470,97.3333,200409,36.3333,90240.3,22.6667,48656,99,198853,27,546.467,0,16:100000:16/64,972.333,10,21833,72.3333,3697,21,995,10.6667,27901.7,95.6667,2681,20.6667 - 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/