From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Brian J. Murrell" Subject: Re: 5x slower guest disk performance with virtio disk Date: Thu, 15 Dec 2011 11:55:31 -0500 Message-ID: <4EEA2683.8080206@interlinx.bc.ca> References: <20111215164434.IsVHDbflPT5f2Ac8ivIKgk@consulting.lsexperts.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigEB1A9E1D34BEABE97F3E90EA" To: kvm@vger.kernel.org Return-path: Received: from lo.gmane.org ([80.91.229.12]:43780 "EHLO lo.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759069Ab1LOQzr (ORCPT ); Thu, 15 Dec 2011 11:55:47 -0500 Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1RbEav-0006iM-Ra for kvm@vger.kernel.org; Thu, 15 Dec 2011 17:55:45 +0100 Received: from d67-193-214-242.home3.cgocable.net ([67.193.214.242]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 15 Dec 2011 17:55:45 +0100 Received: from brian by d67-193-214-242.home3.cgocable.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 15 Dec 2011 17:55:45 +0100 In-Reply-To: <20111215164434.IsVHDbflPT5f2Ac8ivIKgk@consulting.lsexperts.de> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigEB1A9E1D34BEABE97F3E90EA Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 11-12-15 10:47 AM, Stefan Pietsch wrote:=20 >=20 > Did you try to set the cache of the virtio disk to "none"? I didn't. It was set at "default" in virt-manager and I suppose I just assumed that "default" would be reasonable. Changing to "none" has had a good effect indeed: host $ ssh guest dd of=3D/dev/vdb if=3D/dev/zero bs=3D1M oflag=3Ddirect c= ount=3D10000 10000+0 records in 10000+0 records out 10485760000 bytes (10 GB) copied, 49.9241 s, 210 MB/s host $ ssh guest dd of=3D/dev/vdb if=3D/dev/zero bs=3D1M oflag=3Ddirect c= ount=3D10000 10000+0 records in 10000+0 records out 10485760000 bytes (10 GB) copied, 54.7737 s, 191 MB/s host $ ssh guest dd of=3D/dev/vdb if=3D/dev/zero bs=3D1M oflag=3Ddirect c= ount=3D10000 10000+0 records in 10000+0 records out 10485760000 bytes (10 GB) copied, 50.9851 s, 206 MB/s host $ sudo dd of=3D/dev/datavol/disk1 if=3D/dev/zero bs=3D1M oflag=3Ddir= ect count=3D10000 10000+0 records in 10000+0 records out 10485760000 bytes (10 GB) copied, 31.0545 s, 338 MB/s So, about 2/3 of host speed now -- which is much better. Is 2/3 about normal or should I be looking for more? Thanks much! b. --------------enigEB1A9E1D34BEABE97F3E90EA Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk7qJoMACgkQl3EQlGLyuXCR0QCfSBfaEv28vDaNQoIUCxVfK+kP 31sAn0yMImyJOzu8bMzsWwl/K8Fe/3bA =D7rH -----END PGP SIGNATURE----- --------------enigEB1A9E1D34BEABE97F3E90EA--