On Wed, Jun 15, 2011 at 11:04 PM, Anthony Liguori <anthony@xxxxxxxxxxxxx> wrote: > On 06/15/2011 03:13 PM, Prasad Joshi wrote: >> >> On Wed, Jun 15, 2011 at 6:10 PM, Pekka Enberg<penberg@xxxxxxxxxx> wrote: >>> >>> On Wed, Jun 15, 2011 at 7:30 PM, Avi Kivity<avi@xxxxxxxxxx> 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. >> >> QEMU was invoked with following parameters >> >> $ qemu-system-x86_64 -hda<disk image on hard disk> -hdb >> /dev/shm/test.qcow2 -m 1024M > > Looking more closely at native KVM tools, you would need to use the > following invocation to have an apples-to-apples comparison: > > qemu-system-x86_64 -drive file=/dev/shm/test.qcow2,cache=writeback,if=virtio In addition to this it is important to set identical guest RAM sizes (QEMU's -m <ram_mb>) option. If you are comparing with qemu.git rather than qemu-kvm.git then you need to ./configure --enable-io-thread and launch with QEMU's -enable-kvm option. Stefan -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
