Hi, Stefan:
Follow your advice, I have finished the benchmarks with multiple vcpu
(smp) and parallel I/O workloads.
The results still show that the performance of disk with dataplane
enabled did not have advantage over non-dataplane under Random write mode. But
under the Sequence write mode, the former has obvious advantage.
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) :
e). vcpu: 4
./x86_64-softmmu/qemu-system-x86_64 -enable-kvm -smp 4 -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=186.100.8.121,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, 0% Read, 16K data size, 50 outstanding IO; 0% Random,
25% Read, 16K data size, 50 outstanding IO
c). Testing of two disks separately, not simultaneously
3. Testing Results:
RW_mode IOPS_dataplane
IOPS_non_dataplane MBPS_dataplane MBPS_non_dataplane
100% Random /0% Read 303.178867
300.511928 4.737170
4.695499
100% Sequence/25% Read 21748.887189
7631.164060 339.826362
119.236938
----------
Leiqzhang
Best Regards
> -----邮件原件-----
> 发件人: Stefan Hajnoczi [mailto:stefa...@redhat.com]
> 发送时间: 2013年4月4日 15:21
> 收件人: Zhangleiqiang
> 抄送: Stefan Hajnoczi; qemu-devel@nongnu.org; leiqzhang; Haofeng; Luohao
> (brian)
> 主题: Re: 答复: [Qemu-devel] question about performance of dataplane
>
> On Tue, Apr 02, 2013 at 02:02:54AM +0000, Zhangleiqiang wrote:
> > I have also finished the perf testing under Fedora 17 using IOZone, and
> > the
> results also shown that the performance of disk with dataplane enabled did not
> have advantage over non-dataplane.
>
> virtio-blk data plane is a win for parallel I/O workloads (that means
> iodepth > 1). The advantage becomes clearer with SMP guests.
>
> In other words the big advantage is that data plane processes requests
> without blocking the QEMU main loop or vCPU threads.
>
> If your guest has 1 vCPU and/or your benchmarks only do a single stream
> of I/O requests, then the difference may not be measurable.
>
> Stefan
