Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755274Ab0DTUs7 (ORCPT ); Tue, 20 Apr 2010 16:48:59 -0400 Received: from zakopane.cs.ubc.ca ([198.162.52.68]:41391 "EHLO mail.quuxuum.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754666Ab0DTUs5 (ORCPT ); Tue, 20 Apr 2010 16:48:57 -0400 X-Greylist: delayed 423 seconds by postgrey-1.27 at vger.kernel.org; Tue, 20 Apr 2010 16:48:57 EDT Date: Tue, 20 Apr 2010 13:41:51 -0700 To: Tracy Reed , Pasi =?iso-8859-1?Q?K=E4rkk=E4inen?= , xen-devel@lists.xensource.com, Aoetools-discuss@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [Xen-devel] domU is causing misaligned disk writes Message-ID: <20100420204151.GH1708@kremvax.cs.ubc.ca> References: <20100420080958.GN5660@tracyreed.org> <20100420084955.GV1878@reaktio.net> <20100420200004.GQ5660@tracyreed.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20100420200004.GQ5660@tracyreed.org> X-Operating-System: Linux 2.6.31-20-generic x86_64 User-Agent: Mutt/1.5.20 (2010-03-22) X-Delivery-Agent: TMDA/1.1.12 (Macallan) From: Brendan Cully Mail-Followup-To: treed@ultraviolet.org, pasik@iki.fi, xen-devel@lists.xensource.com, Aoetools-discuss@lists.sourceforge.net, linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2206 Lines: 51 On Tuesday, 20 April 2010 at 13:00, Tracy Reed wrote: > On Tue, Apr 20, 2010 at 11:49:55AM +0300, Pasi K?rkk?inen spake thusly: > > Are you using filesystems on normal partitions, or LVM in the domU? > > I'm pretty sure this is a domU partitioning problem. > > Also: What changes in the view of the partitioning between domU and > dom0? Wouldn't a partitioning error manifest itself in tests in the > dom0 as well as in the domU? > > BTW: The dd from the last time in my last email finally finished: > > # dd if=/dev/zero of=/dev/xvdg1 bs=4096 count=3000000 > 3000000+0 records in > 3000000+0 records out > 12288000000 bytes (12 GB) copied, 734.714 seconds, 16.7 MB/s > > If I run that very same dd as above (the last test in my previous > email) with the same partition setup again but this time from the > dom0: > > # dd if=/dev/zero of=/dev/etherd/e6.1 bs=4096 count=3000000 > 3000000+0 records in > 3000000+0 records out > 12288000000 bytes (12 GB) copied, 107.352 seconds, 114 MB/s > > # /sbin/sfdisk -d /dev/etherd/e6.1 > # partition table of /dev/etherd/e6.1 > unit: sectors > > /dev/etherd/e6.1p1 : start= 64, size=566226926, Id=83 > /dev/etherd/e6.1p2 : start= 0, size= 0, Id= 0 > /dev/etherd/e6.1p3 : start= 0, size= 0, Id= 0 > /dev/etherd/e6.1p4 : start= 0, size= 0, Id= 0 > > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz > avgqu-sz await svctm %util > sda 0.00 17350.80 0.60 275.60 22.40 72540.00 > 525.43 97.94 344.01 3.62 100.02 > sdb 0.00 17374.80 1.20 256.00 28.00 74848.00 > 582.24 136.20 527.72 3.89 100.02 You could also be limited by the size of the block request ring (I believe the ring is normally only one page) -- the ring needs to be large enough to handle the bandwidth delay product, and AoE means the delay is probably higher than normal. Do you get better performance against a local partition? -- 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/