Re: [Qemu-devel] 答复: 答复: 答复: 答复: quest ion about performance of dataplane

[Zhangleiqiang]

> -----Original Message-----
> From: Abel Gordon [mailto:address@hidden
> Sent: Monday, April 08, 2013 7:04 PM
> To: Zhangleiqiang
> Cc: address@hidden; Luohao (brian); Haofeng; 张磊强;
> address@hidden; Stefan Hajnoczi; Stefan Hajnoczi
> Subject: Re: 答复: [Qemu-devel] 答复: 答复: 答复: question about
> performance of dataplane
> 
> Zhangleiqiang <address@hidden> wrote on 08/04/2013 12:06:17
> PM:
> 
> > I think maybe Anthony is right. In previous benchmarks, maybe the
> > non-dataplane already reached the physical disk's IOPS upper limit.
> 
> Yep, agree. Try to run the same benchmark in the host to see
> what is the bare-metal performance of your system (upper limit)
> and how far are dataplane and non-dataplane from this value.
> Note your are currently focusing on throughput but you should also
> consider latency and CPU utilization.
> 
> > So I did another benchmark which ensures the vcpus is less than the
> > host's cores, but also make continuous IO pressure by one VM when
> > testing in the other VM. The result showed that dataplane did have
> > some advantage over non-dataplane.
> >
> > 1. IO Pressure Mode:  8 worker, 16K IO size, 25% Read, 100% Random,
> > and 50 outstanding IO
> > 2. Benchmark Mode:  8 worker, 16K IO size, 0% Read,  100% Random,
> > and 50 outstanding IO
> > 2. Testing Results:
> >    a). IOPS:     178.324867 (non-dataplane)  vs  230.956328
> (dataplane)
> >    b). MBPS:     2.786326 (non-dataplane)  vs  3.608693 (dataplane)
> 
> Note that running other VM just to "synthetically" degrade the
> performance of the system may cause some side effects and confuse the
> results (e.g. the "other" VM may stress the system differently and
> do more pressure when you use dataplane than when you don't use
> dataplane)
> 

I think do multiple benchmarks with the same situation and calc the average 
value will eliminate the "side effects".

> Last thing, IMHO, you should also evaluate scalability:
> how dataplane and no-dataplane perform  when you run multiple VMs ?
> 
> For example,
>   first  1 VM  with 2 VCPUs
>   then   2 VMs with 2 VCPUs each
>   then   3 VMs with 2 VCPUs each
>   ...
>   up to 12 VMs with 2 VCPUs each
> 
> It seems like you unintentionally tested what happens with 2 VMs when
> you added the "other" VM to create I/O pressure.

Indeed, the fact I used 2 VMs in previous benchmark is to ensure the vcpus is 
less than the host's cores, eg, each vm had 8 vpus. 
Thanks for your advice, I will evaluate the scalability,  :)