From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1InDvd-0000Ac-R8 for qemu-devel@nongnu.org; Wed, 31 Oct 2007 09:48:17 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1InDvc-00008H-9m for qemu-devel@nongnu.org; Wed, 31 Oct 2007 09:48:17 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1InDvc-00007s-3x for qemu-devel@nongnu.org; Wed, 31 Oct 2007 09:48:16 -0400 Received: from mx1.redhat.com ([66.187.233.31]) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1InDvb-0005bM-FQ for qemu-devel@nongnu.org; Wed, 31 Oct 2007 09:48:15 -0400 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.13.8/8.13.1) with ESMTP id l9VDm4nl029231 for ; Wed, 31 Oct 2007 09:48:04 -0400 Received: from file.surrey.redhat.com (file.fab.redhat.com [10.33.63.6]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l9VDm36d018955 for ; Wed, 31 Oct 2007 09:48:03 -0400 Received: (from berrange@localhost) by file.surrey.redhat.com (8.13.1/8.13.1/Submit) id l9VDm2ZS028458 for qemu-devel@nongnu.org; Wed, 31 Oct 2007 13:48:02 GMT Date: Wed, 31 Oct 2007 13:48:02 +0000 From: "Daniel P. Berrange" Subject: Re: [Qemu-devel] [PATCH 0/3] Add SCSI support for PC target Message-ID: <20071031134802.GA25965@redhat.com> References: <11936114152690-git-send-email-Laurent.Vivier@bull.net> <20071031095015.GB9419@karma.qumranet.com> <47285633.3060207@bull.net> <20071031125653.GA10952@karma.qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20071031125653.GA10952@karma.qumranet.com> Content-Transfer-Encoding: quoted-printable Reply-To: "Daniel P. Berrange" , qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org On Wed, Oct 31, 2007 at 02:56:53PM +0200, Dan Kenigsberg wrote: > On Wed, Oct 31, 2007 at 11:17:23AM +0100, Laurent Vivier wrote: > > Dan Kenigsberg a =E9crit : > > >Hi, > > > > > >I have some newby's questions: is a speedup expected, comparing to i= de > >=20 > > We should have a speedup. >=20 > Would you suggest where it could show? I was trying simple dd and > bonnie++, and saw big variace between consequtive runs, but little > change between mounting an image with if=3Dide and if=3Dscsi. Was I doi= ng > something wrong? Using dd is pretty useless as a benchmark. bonnie++ can work sometimes if you tune the size of its I/O ops wrt to the amount of RAM in your host and guest. The big variance is likely caused by doing small enough I/O that the cache in either host or guest can buffer your data at times.= =20 IOZone is a benchmark I find gives better results, though it does take a=20 hell of a long time to run. Tune IOZone params to do increasingly large I/O chunks, so that it will exceed RAM in both host & guest & let it repeat many times & you should get to some stable benchmark results. There were some results at the last Xen summit comparing the IDE & SCSI drivers in QEMU(KVM) against Xen paravirt - the SCSI results were very impressive & significantly ahead of IDE. http://xen.org/files/xensummit_4/xen_summit_2007_spring_hvm_charts_Harper= .pdf Regards, Dan. --=20 |=3D- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 24= 96 -=3D| |=3D- Perl modules: http://search.cpan.org/~danberr/ = -=3D| |=3D- Projects: http://freshmeat.net/~danielpb/ = -=3D| |=3D- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 950= 5 -=3D|=20