Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759786AbXFWRa1 (ORCPT ); Sat, 23 Jun 2007 13:30:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756105AbXFWRaU (ORCPT ); Sat, 23 Jun 2007 13:30:20 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:41768 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754389AbXFWRaT (ORCPT ); Sat, 23 Jun 2007 13:30:19 -0400 Date: Sat, 23 Jun 2007 10:29:49 -0700 From: Andrew Morton To: Carlo Wood Cc: Henrique de Moraes Holschuh , Arjan van de Ven , Jeff Garzik , linux-kernel@vger.kernel.org Subject: Re: SATA Harddisk speed drop of 100 MB/s Message-Id: <20070623102949.09e36fb9.akpm@linux-foundation.org> In-Reply-To: <20070623025906.GA24336@alinoe.com> References: <20070620224847.GA5488@alinoe.com> <4679B2DE.9090903@garzik.org> <1182397012.2863.0.camel@laptopd505.fenrus.org> <20070622162142.GA603@alinoe.com> <20070622211746.GB21769@khazad-dum.debian.net> <20070622212758.GA6970@alinoe.com> <20070623013132.GA1702@khazad-dum.debian.net> <20070623025906.GA24336@alinoe.com> X-Mailer: Sylpheed 2.4.1 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1948 Lines: 48 On Sat, 23 Jun 2007 04:59:06 +0200 Carlo Wood wrote: > On Fri, Jun 22, 2007 at 10:31:32PM -0300, Henrique de Moraes Holschuh wrote: > > for i in /sys/block/sd*/queue/scheduler ; do echo -n "scheduler for $i was:" ; cat $i ; echo anticipatory > $i ; done > > > > Should show you the scheduler for all libata/scsi discs, and switch to > > anticipatory. It probably works for hd* as well, but I don't have any > > around to test. > > > > I had ridiculous md raid performance (on resync) using cfq at least once. > > Unfortunately I never bothered trying to track it down, and I didn't check > > the throughput after the resync was done either. Also, I don't recall the > > kernel version, but it was either 2.6.18 or 2.6.20. > > Just one kernel version? The problem here is in every > kernel revision after 551c012d7eea3dc5ec063c7ff9c718d39e77634f > > 2.6.20-rc2,rc3,rc4,rc5,rc6,rc7 ... 2.6.20 ... 2.6.21 ... 2.6.22-rc5 > > noop: > Timing buffered disk reads: 254 MB in 3.00 seconds = 84.66 MB/sec > > anticipatory: > Timing buffered disk reads: 252 MB in 3.02 seconds = 83.43 MB/sec > > deadline: > Timing buffered disk reads: 258 MB in 3.02 seconds = 85.41 MB/sec > > cfq: > Timing buffered disk reads: 194 MB in 3.03 seconds = 64.06 MB/sec > > The normal value is cfq. So, all other schedulars are somewhat faster, > but still far from the correct 165 MB/s. > Please see http://bugzilla.kernel.org/show_bug.cgi?id=8636 In that report a pretty large slowdown with CFQ has been identified. Jens has plunked a patch in there (Comment #50) and then ran away on vacation. If someone can test that patch and demonstrate its goodness, I'll queue it up, thanks. - 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/