[Qemu-devel] question about performance of dataplane

[Zhangleiqiang]

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
        d). VM start cmd (os: win7/qed, disk1: raw/non-dataplane/10G/NTFS, 
disk2: raw/dataplane/10G/NTFS) :

./x86_64-softmmu/qemu-system-x86_64  -enable-kvm -name win7 -M pc-0.15 -m 1024 
-boot c -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5 -monitor 
stdio -drive file=/home/win7.qed,if=none,format=qed,cache=none,id=drive0 
-chardev spicevmc,id=charchannel2,name=vdagent -device 
virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel2,id=channel2,name=com.redhat.spice.0
 -chardev pty,id=charchannel3 -device 
virtserialport,bus=virtio-serial0.0,nr=2,chardev=charchannel3,id=channel3,name=arbitrary.virtio.serial.port.name
 -usb -device usb-tablet,id=input0 -spice port=3007,addr=****,disable-ticketing 
-vga qxl -global qxl.vram_size=67108864 -device 
AC97,id=sound0,bus=pci.0,addr=0x4 -device 
virtio-blk-pci,drive=drive0,bus=pci.0,addr=0x6,bootindex=1 -drive 
id=drive1,if=none,cache=none,format=raw,file=/home/data.img -device 
virtio-blk-pci,drive=drive1,bus=pci.0,addr=0x7 -drive 
id=drive2,if=none,cache=none,format=raw,file=/home/data2.img,aio=native -device 
virtio-blk-pci,drive=drive2,bus=pci.0,addr=0x8,scsi=off,x-data-plane=on,config-wce=off


2. Testing Tool And Testing Params:
        a). Only IOMeter App Running in VM, and no other IO in Host (Dom0)
        b). 100% Random IO, data_size(16K/32K/4K), RW_Ratio(0%/25%/75% Read)
        c). Testing of two disks separately, not simultaneously

3. Testing Results:

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



----------
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
>