[Qemu-devel] 答复: question about perfo rmance of dataplane

[Zhangleiqiang]

> -----邮件原件-----
> 发件人: Anthony Liguori [mailto:address@hidden
> 发送时间: 2013年4月7日 22:06
> 收件人: Zhangleiqiang; Stefan Hajnoczi; address@hidden
> 抄送: Zhangleiqiang; Luohao (brian); address@hidden; Haofeng;
> leiqzhang
> 主题: Re: [Qemu-devel] question about performance of dataplane
> 
> Zhangleiqiang <address@hidden> writes:
> 
> >
> > 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
> 
> 
> 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 :-)
>

Maybe the result table in mail is not so clear, the IOPS is about 300, but the 
throughput is just about 1-9 MB/s, :)

> Regards,
> 
> Anthony Liguori
> 
> >
> >
> >
> > ----------
> > Leiqzhang
> >
> > Best Regards
> >
> >
> >> 发件人: address@hidden
> [mailto:address@hidden 代表
> leiqzhang
> >> 发送时间: 2013年3月28日 12:03
> >> 收件人: Stefan Hajnoczi
> >> 抄送: address@hidden; address@hidden;
> address@hidden; 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
> >>