Re: [Qemu-devel] [question] the patch which affect performance of virtio-scsi

[Paolo Bonzini]

On 07/02/2015 12:26, Wangting (Kathy) wrote:
> OK, Thank you very much for your detailed explanation.
> 
> But I have another question about the big change from qemu-1.5.3 to 
> qemu-1.6.0-rc0.
> 
> When I use ramdisk for IO performance testing, the result is as follows.
> 
> [fio-test]          rw         bs         iodepth    jobs       bw         
> iops
> ------------------------------------------------------------------------------------
> qemu-1.5.3          read       4k         32          1         285MB/s    
> 73208
> qemu-1.6.0-rc0      read       4k         32          1         253MB/s    
> 64967
> 
> And virtio-blk is the same.
> 
> I know there are so many differences between qemu-1.5 and qemu-1.6, but I am 
> confused about
> what new features impact the performance so much. Do you know it?

No, sorry.  Please try newer versions first and see if this was fixed.
QEMU 1.6 is more than a year old.

Paolo