[Paraview] understanding CPU usage for parallel setups

[Marc Baaden]

(NB: this is a follow-up on a previous thread with several issues, 
focusing on one of them )


kmorel at sandia.gov said:
>>> - when I start pvserver with eg -np 4, I only have 3 pvserver tasks
>>> running at about 99%, and occasionnally a 4th at ~20%. Is that to
>>> be expected?

>> I would not say it is expected, but it is not very surprising.  There
>> are several benign reasons this might be the case. 

Hmm, what I meant is that it looks like if I start with -np X, exactly 
X-1 CPUs will run at 99% and the Xth CPU is idle unless I interact with 
the system. Still (from eg the artefacts mentioned in previous mails) 
paraview does subdivide the data into X parts and not into X-1 parts.

What are the benign reasons that you mention?

I also wonder how one should distribute CPUs, eg on a 4-CPU 
workstation, should one start the paraview client (~ 1 CPU) plus the pvserver 
with -np 3 (3 CPUs, total=4) or rather pvserver -np 4 (given that one 
process seems idle most of the time)?

Thanks in advance, 
  Marc Baaden

-- 
 Dr. Marc Baaden  - Institut de Biologie Physico-Chimique, Paris
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