From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gordan Bobic Subject: Re: virtio disk slower than IDE? Date: Sun, 15 Nov 2009 12:00:09 +0000 Message-ID: <4AFFED49.9010305@bobich.net> References: <4AFEBD59.2090002@bobich.net> <4AFFCF18.1080509@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: kvm@vger.kernel.org Return-path: Received: from 78-86-195-86.zone2.bethere.co.uk ([78.86.195.86]:54489 "EHLO sentinel1.shatteredsilicon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752235AbZKOMAH (ORCPT ); Sun, 15 Nov 2009 07:00:07 -0500 Received: from ariia.shatteredsilicon.net (ariia.shatteredsilicon.net [10.2.3.1]) by sentinel1.shatteredsilicon.net (Postfix) with ESMTP id C98D34C280 for ; Sun, 15 Nov 2009 12:00:09 +0000 (GMT) In-Reply-To: <4AFFCF18.1080509@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Dor Laor wrote: > On 11/14/2009 04:23 PM, Gordan Bobic wrote: >> I just tried paravirtualized virtio block devices, and my tests show >> that they are approximately 30% slower than emulated IDE devices. I'm >> guessing this isn't normal. Is this a known issue or am I likely to have >> mosconfigured something? I'm using 64-bit RHEL/CentOS 5 (both host and >> guest). > > Please try to change the io scheduler on the host to io scheduler, it > should boost your performance back. I presume you mean the deadline io scheduler. I tried that (kernel parameter elevator=deadline) and it made no measurable difference compared to the cfq scheduler. Gordan