From mboxrd@z Thu Jan 1 00:00:00 1970 From: Asdo Subject: Performance of virtio-blk? Date: Sat, 06 Mar 2010 15:58:12 +0100 Message-ID: <4B926D84.3020106@shiftmail.org> 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 mx2.isti.cnr.it ([194.119.192.4]:1245 "EHLO mx2.isti.cnr.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753882Ab0CFR6j (ORCPT ); Sat, 6 Mar 2010 12:58:39 -0500 Received: from conversionlocal.isti.cnr.it by mx.isti.cnr.it (PMDF V6.5-b2 #31825) id <01NKFNJRP1VKBFH9O0@mx.isti.cnr.it> for kvm@vger.kernel.org; Sat, 06 Mar 2010 15:58:09 +0100 Received: from [10.0.0.1] (host-84-220-173-105.cust-adsl.tiscali.it [84.220.173.105]) by mx.isti.cnr.it (PMDF V6.5-b2 #31826) with ESMTPSA id <01NKFNJR2A66C51VYS@mx.isti.cnr.it> for kvm@vger.kernel.org; Sat, 06 Mar 2010 15:58:09 +0100 Sender: kvm-owner@vger.kernel.org List-ID: Dear kvm developers firstly thank you for doing such a great job on KVM. Following this list I see great ongoing progresses on virtio-net, now even more with the vhost but I see virtio-blk very rarely mentioned. We have an old kvm installation (host kernel is also old at 2.6.24) and I don't seem to be able to get good performances out of virtio-blk, I think it doesn't surpass 40MB/sec (difficult to benchmark as there are many VMs running now), while we have a large RAID on the host. We would really need fast disk access more than network access. How is the speed on the newest KVMs and kernels? (suppose the HD is not the bottleneck, e.g. on a fast RAID) Also is there any guide on how to tune it? Is a vhost-blk planned? For vhost-net I read you got to the 7Gbit/sec! 700MB/sec disk access could be enough :-D