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Subject: Re: [OMPI users] Questions about binding processes
From: NGUYEN Laurent (laurent.nguyen_at_[hidden])
Date: 2010-05-10 07:16:30


Ok, thank you for your answer. I think this rankfile feature is very
interesting to run some jobs like MPMD jobs or hybrid jobs
(multithreaded or GPU for examples).

Regards,

-- 
--
NGUYEN Laurent
HPC Engineer
CS:SI
email: laurent.nguyen_at_[hidden]
web: http://www.c-s.fr
CS:SI
22 avenue Galilée
92350  Le Plessis Robinson
Terry Dontje <terry.dontje_at_[hidden]> a écrit :
> NGUYEN Laurent wrote:
>> Hello,
>>
>> I'm trying to understand the difference between theses two options:
>>
>> " --mca mpi_paffinity_alone 1 "
>> and
>> " --bind-to-core "
>>
>> To me, it's the same thing (may be paffinity have maffinity in  
>> addition) but the purpose af theses options is to bind MPI process  
>> to processors. Which is the best to obtain performances?
>>
> They are essentially the same thing.  The history is that  
> mpi_paffinity_alone came first.  Then a group of us decided that we  
> wanted to be able to do more than just core binding (like  
> bind-to-socket and eventually others) so we decided a more  
> descriptive name made sense.  I would suggest sticking with  
> --bind-to-core just so thinks look clear in your mpirun command.   
> That and the possibility that one day mpi_paffinity_alone is  
> deprecated.
>> I have another question about processes bindings: I use rankfiles  
>> to have a precise binding of my process on processor or socket (it  
>> useful for hybrid computing like pthread or OpenMP). I read you  
>> don't want to maintain this feature: how can I substitute it?
> IMO, I say we do support it and will until we find a suitable  
> replacement (there is a proposal that Jeff and I have bounced around  
> to each other intermittently but have not brought it to the  
> community).   There have been discussion about lack of testing of  
> rankfiles and other binding related items making it hard for some to  
> feel comfortable about putting code back that may have side negative  
> side affects.  But I don't equate that to mean we will not support  
> or take bug reports on the rankfile feature.
>
> -- 
> Oracle
> Terry D. Dontje | Principal Software Engineer
> Developer Tools Engineering | +1.650.633.7054
> Oracle * - Performance Technologies*
> 95 Network Drive, Burlington, MA 01803
> Email terry.dontje_at_[hidden] <mailto:terry.dontje_at_[hidden]>
>
>
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