From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [ANNOUNCE] Native Linux KVM tool v2 Date: Wed, 15 Jun 2011 16:53:36 -0500 Message-ID: <4DF929E0.1030806@codemonkey.ws> References: <1308153214.7566.6.camel@jaguar> <4DF8DE26.1070301@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Pekka Enberg , Avi Kivity , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Andrew Morton , Linus Torvalds , Ingo Molnar , Sasha Levin , Cyrill Gorcunov , Asias He , Jens Axboe To: Prasad Joshi Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 06/15/2011 03:13 PM, Prasad Joshi wrote: > On Wed, Jun 15, 2011 at 6:10 PM, Pekka Enberg wrote: >> On Wed, Jun 15, 2011 at 7:30 PM, Avi Kivity wrote: >>> On 06/15/2011 06:53 PM, Pekka Enberg wrote: >>>> >>>> - Fast QCOW2 image read-write support beating Qemu in fio benchmarks. See >>>> the >>>> following URL for test result details: https://gist.github.com/1026888 >>> >>> This is surprising. How is qemu invoked? >> >> Prasad will have the details. Please note that the above are with Qemu >> defaults which doesn't use virtio. The results with virtio are little >> better but still in favor of tools/kvm. >> > > The qcow2 image used for testing was copied on to /dev/shm to avoid > the disk delays in performance measurement. Our experience has been that this is actually not a great way to simulate fast storage. Spindle based storage has very different characteristics than memory as there is a significant cost for seeking. -hdb uses IDE too. That's pretty unfair since IDE is limited to a single request at a time whereas virtio can support multiple requests (and native kvm tools is using virtio). Regards, Anthony Liguori