Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754919Ab0DTUDL (ORCPT ); Tue, 20 Apr 2010 16:03:11 -0400 Received: from mail.copilotco.com ([216.105.40.123]:33609 "EHLO mail.copilotco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754213Ab0DTUDK (ORCPT ); Tue, 20 Apr 2010 16:03:10 -0400 Date: Tue, 20 Apr 2010 13:03:10 -0700 From: Tracy Reed To: Pasi =?iso-8859-1?Q?K=E4rkk=E4inen?= Cc: 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: <20100420200310.GR5660@tracyreed.org> Mail-Followup-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 References: <20100420080958.GN5660@tracyreed.org> <20100420084955.GV1878@reaktio.net> <20100420193952.GP5660@tracyreed.org> <20100420195442.GC1878@reaktio.net> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="IlmwW192PJ8CjiJ7" Content-Disposition: inline In-Reply-To: <20100420195442.GC1878@reaktio.net> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1650 Lines: 52 --IlmwW192PJ8CjiJ7 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Apr 20, 2010 at 10:54:42PM +0300, Pasi K=E4rkk=E4inen spake thusly: > Please try with "bs=3D1024k" and maybe with "bs=3D64k" aswell. > =20 > 4k blocksize transfer will always be slower in domU than in dom0 > since virtual disk abstraction makes some overhead, which is more > visible with small blocksizes. But overhead in domU wouldn't be causing all of these reads. I am doing a test with bs=3D64k now: Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sda 0.00 3258.20 964.00 54.00 3903.20 13652.80 34.49 2.75 2.71 0.68 68.88 sdb 0.00 3270.20 974.80 54.00 3940.80 13710.40 34.31 2.42 2.38 0.55 56.22 > So the speed is the same to the partitioned disk than to the raw disk?=20 > What disk backend are you using in dom0? phy:? tap:aio: ? Yes.=20 I am using phy: disk backend. Should I be using something else? --=20 Tracy Reed http://tracyreed.org --IlmwW192PJ8CjiJ7 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (GNU/Linux) iD8DBQFLzgh+9PIYKZYVAq0RAj+EAKCgFWRIhdF2z9MAfb5JqqS/84kbrwCeKf3h 4tuevARQqS5DJkalfRYDpFg= =QmcF -----END PGP SIGNATURE----- --IlmwW192PJ8CjiJ7-- -- 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/