Re: compute performace problem

[Keir Fraser <Keir.Fraser@cl.cam.ac.uk>]

On 23 Apr 2005, at 16:06, Steven Hand wrote:

>> One of my users discovered large deviations in execution time for his
>> mpi jobs on xenUs.  I can reproduce the problem running his job on
>> a single VM.  On a native linux box the job completes in 64 secs +/-
>> a second or so.  On a xenU, it completes somewhere between 64 and 250
>> secs.  This is true on 2.0.5 (2.6.10-xenU) and 
>> 2.0-testing(2.6.11-xenU).
>> I tried xen-unstable but it seemed any task was taking 4 times as
>> long as on 2.0 so I guess its still too unstable.
>>
>> Any suggestions I can try?
>
> Can you repeat the experiment using the round robin scheduler in Xen 
> (i.e.
> boot with xen option "sched=rrobin")?

Probably will be worse -- I'm not certain that the rrobin scheduler is 
even smart enough not to include the idle domain in its round-robin 
schedule. An important reason why I killed it in the unstable tree.

  -- Keir