Zhangleiqiang <zhangleiqi...@huawei.com> writes: > Hi, Stefan： > > I have done some testing to compare the performance of dataplane and > non-dataplane. But the result did not meet my expectations, the performance > of disk with dataplane enabled did not have advantage over non-dataplane. > > The following contains the environment info and testing results. > Does my testing method or testing environment have something wrong ? Could > you give me some advice? I can provide more information if need. > > > 1. Environment: > a). Qemu 1.4 master branch > b). kernel: 3.5.0-2.fc17.x86_64 > c). virtual disks location: the same local SATA harddisk > with ext4 fs
I doubt you'll see any performance difference with a single SATA drive. There's no real parallelism possible as you have exactly one spindle available. > datasize/RW_Ratio IOPS_dataplane IOPS_non_dataplane > MBPS_dataplane MBPS_non_dataplane > 16K/0% 294.094948 293.609606 > 4.595234 4.58765 > 16K/25% 283.096745 281.649258 > 4.423387 4.40077 > 16K/75% 316.039801 309.585336 > 4.938122 4.837271 > 32K/0% 257.529537 258.806128 > 8.047798 8.087692 > 32K/25% 253.729281 253.756673 > 7.92904 7.929896 > 32K/75% 292.384568 280.991434 > 9.137018 8.780982 > 4K/0% 321.599352 324.116063 > 1.256247 1.266078 > 4K/25% 309.906635 309.294278 > 1.210573 1.208181 > 4K/75% 350.168882 > 350.772329 1.367847 > 1.370204 You are getting 300 MB/s to a single SATA disk? I strongly suspect you are seeing cache interaction. I'd suggest disabling WCE on the disk if you're going to benchmark like this. I'd also guess 300 MB/s is what you're maxing out at with native too. So presumably normal virtio-blk is already getting close to native performance. dataplane certainly isn't going to give you better than native performance :-) Regards, Anthony Liguori > > > > ---------- > Leiqzhang > > Best Regards > > >> 发件人: qemu-devel-bounces+zhangleiqiang=huawei....@nongnu.org >> [mailto:qemu-devel-bounces+zhangleiqiang=huawei....@nongnu.org] 代表 leiqzhang >> 发送时间: 2013年3月28日 12:03 >> 收件人: Stefan Hajnoczi >> 抄送: pbonz...@redhat.com; qemu-devel@nongnu.org; stefa...@redhat.com; 张 磊强 >> 主题: [Qemu-devel] 回复： dataplane bug: fail to start Windows VM with dataplane >> enable >> >> Hi, Stefan: >> >> Thank for your reply and patch. I have done the test for Windows 7, >> Windows 2003, and fedora. >> >> The patch has fixed the problem now, thanks. >> >> -- >> leiqzhang >> Sent by Sparrow >> >> 在 2013年3月27日星期三，23:41，Stefan Hajnoczi 写道： >> On Tue, Mar 26, 2013 at 11:10:35PM +0800, 张磊强 wrote: >> Hi, Paolo && Stefan: >> >> When I test the dataplane feature with qemu master, I find that >> Windows (Windows 7 and Windows 2003) VM will hang if dataplane is >> enabled. But if I try to start a Fedora VM, it can start normally. >> >> The command I boot QEMU is: >> x86_64-softmmu/qemu-system-x86_64 -enable-kvm -m 1024 -smp 2 -drive >> file=win7.img,if=none,id=drive-virtio-disk,format=raw,cache=none,aio=native >> -device >> virtio-blk-pci,config-wce=off,scsi=off,x-data-plane=on,drive=drive-virtio-disk,id=virtio-disk >> >> I found the similar bug has reported some days ago: >> http://lists.nongnu.org/archive/html/qemu-devel/2013-03/msg02200.html >> . And a patch for this bug has already committed by Paolo at Mar 13: >> http://lists.nongnu.org/archive/html/qemu-devel/2013-03/msg02200.html >> . >> >> But it cannot work under my environment. Could you give me some advise >> to debug this problem ? I can provide more information if need. >> >> I sent a fix and CCed you on the patch. Please test it if you have >> time. >> >> Stefan >>
