From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:53775) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S52Xk-00032P-UF for qemu-devel@nongnu.org; Tue, 06 Mar 2012 17:07:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S52Xc-0005j5-Sq for qemu-devel@nongnu.org; Tue, 06 Mar 2012 17:07:40 -0500 Received: from blade3.isti.cnr.it ([194.119.192.19]:2359) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S52Xc-0005io-M2 for qemu-devel@nongnu.org; Tue, 06 Mar 2012 17:07:32 -0500 Received: from [10.0.55.100] ([94.36.81.210]) by mx.isti.cnr.it (PMDF V6.5-x6 #31988) with ESMTPSA id <01OCT9K8FFD4KUGT11@mx.isti.cnr.it> for qemu-devel@nongnu.org; Tue, 06 Mar 2012 23:07:15 +0100 (MET) Date: Tue, 06 Mar 2012 23:07:40 +0100 From: Reeted In-reply-to: Message-id: <4F568AAC.6060206@shiftmail.org> MIME-version: 1.0 Content-type: text/plain; format=flowed; charset=ISO-8859-1 Content-transfer-encoding: 7bit References: <20120210143639.GA17883@gmail.com> <4F54E620.8060400@tuxadero.com> <4F54ED84.7030601@tuxadero.com> Subject: Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi , Martin Mailand , Dongsu Park Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org On 03/06/12 13:59, Stefan Hajnoczi wrote: > On Mon, Mar 5, 2012 at 4:44 PM, Martin Mailand wrote: >> Am 05.03.2012 17:35, schrieb Stefan Hajnoczi: >> >>>> 1. Test on i7 Laptop with Cpu governor "ondemand". >>>>> v0.14.1 >>>>> bw=63492KB/s iops=15873 >>>>> bw=63221KB/s iops=15805 >>>>> >>>>> v1.0 >>>>> bw=36696KB/s iops=9173 >>>>> bw=37404KB/s iops=9350 >>>>> >>>>> master >>>>> bw=36396KB/s iops=9099 >>>>> bw=34182KB/s iops=8545 >>>>> >>>>> Change the Cpu governor to "performance" >>>>> master >>>>> bw=81756KB/s iops=20393 >>>>> bw=81453KB/s iops=20257 >>> Interesting finding. Did you show the 0.14.1 results with >>> "performance" governor? >> >> >> Hi Stefan, >> all results are with "ondemand" except the one where I changed it to >> "performance" >> >> Do you want a v0.14.1 test with the governor on "performance"? > Yes, the reason why that would be interesting is because it allows us > to put the performance gain with master+"performance" into > perspective. We could see how much of a change we get. Me too, I would be interested in seeing 0.14.1 being tested with performance governor so to compare it to master with performance governor, to make sure that this is not a regression. BTW, I'll take the opportunity to say that 15.8 or 20.3 k IOPS are very low figures compared to what I'd instinctively expect from a paravirtualized block driver. There are now PCIe SSD cards that do 240 k IOPS (e.g. "OCZ RevoDrive 3 x2 max iops") which is 12-15 times higher, for something that has to go through a real driver and a real PCI-express bus, and can't use zero-copy techniques. The IOPS we can give to a VM is currently less than half that of a single SSD SATA drive (60 k IOPS or so, these days). That's why I consider this topic of virtio-blk performances very important. I hope there can be improvements in this sector... Thanks for your time R.