[Pw_forum] Re: Re: Re: Woodcrest vs Opteron performance in pwscf calc. (Huiqun Zhou)

[Huiqun Zhou]

Hi, list-users,

Here I report my test result on a completely clean woodcrest node:
1 cores : 3m54s (3m53.51s)
2 cores: 2m12s (2m10.61s)
4 cores: 1m22s (1m17.38s)

Comparing the results of this test and that in my previous post, we can 
conclude
(1) Setting OMP_NUM_THREADS to 1 or not has no influence on the speed.
  This may be due to the fact that Intel BLAS and LAPACK libraries assume
  that it's equal to 1 while the Scalapack and sparse solver in MKL library 
set
  OMP_NUM_THREADS=2.
(2) It seems that the memory contention is significant:
  1 core : 3m54s (clean) vs. 4m44s (loaded on other 2 cores)
  2 cores: 2m12s (clean vs. 2m52s (loaed on other 2 cores)

Huiqun Zhou

----- Original Message ----- 
From: "Huiqun Zhou" <hqzhou at nju.edu.cn>
To: <pw_forum at pwscf.org>
Sent: Saturday, August 05, 2006 3:55 PM
Subject: Re: [Pw_forum] Re: Re: Re: Woodcrest vs Opteron performance in 
pwscf calc. (Huiqun Zhou)


> Cesar and list-users,
>
> I'm sorry for my fault. You're right. As there is only 2 cores on one of
> my woodcrest nodes are spare right now, I re-run the tests on them and
> the opteron node.
>
> Here are the results:
> (1) Opteron 285 (2.6 GHz)
>  Nearly same as my previous reported numbers.
>
> (2) Woodcrest (2.66 GHz)
>  1 core : 4m44s (4m42.74s)
>  2 cores: 2m52s (2m49.49s)
>  The results were got while another pwscf job was running on other
>  two cores.
>
> I'll run the same test on the node next week (maybe) when it becomes
> totally clean and spare. So, we can get an impression of how memory
> contention would influence the speed as Axel prompted.
>
> Have a nice weekend!
>
> Huiqun Zhou
>
> ----- Original Message ----- 
> From: <cesards at msi.umn.edu>
> To: <pw_forum at pwscf.org>
> Sent: Saturday, August 05, 2006 6:04 AM
> Subject: [Pw_forum] Re: Re: Re: Woodcrest vs Opteron performance in pwscf 
> calc. (Huiqun Zhou)
>
>
>> Dear Huiqun Zhou,
>>
>> In your job there is a line
>>
>> NUM_OMP_THREADS=1
>>
>> Should be
>>
>> OMP_NUM_THREADS=1
>>
>> I don't know how many threads your system defaults to, but if it is more
>> than one, your tests are flowed.
>>
>> Yours,
>>
>> Cesar R.S. da Silva
>>
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>
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