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List:       beowulf
Subject:    Re: [Beowulf] VMC - Virtual Machine Console
From:       Reuti <reuti () staff ! uni-marburg ! de>
Date:       2008-01-27 11:17:12
Message-ID: EDFD4DB0-3790-407E-97C0-02D0A006C81D () staff ! uni-marburg ! de
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Hi,

Am 21.01.2008 um 04:20 schrieb Rayson Ho:

> On Jan 18, 2008 5:53 PM, Bernard Li <bernard@vanhpc.org> wrote:
> > -- but I'd also like to hear whether there are any general  
> > performance
> > benefits to setting CPU affinity.  Do major schedulers support this?
> > Would this help with embarrassingly parallel jobs VS large MPI  
> > jobs on
> > manycore machines?
> 
> I am working on adding processor affinity support for serial and
> parallel jobs for Grid Engine, and I am working with the OpenMPI
> developers to define an interface.
> 
> http://gridengine.sunsource.net/servlets/BrowseList? 
> list=dev&by=thread&from=27044
> http://www.open-mpi.org/community/lists/devel/2008/01/2949.php
> http://www.open-mpi.org/community/lists/devel/2008/01/2964.php
> 
> BTW, LSF 7.0.2 supports processor affinity for serial jobs. However,
> supporting processor affinity for serial jobs is only useful when the
> OS scheduler is dumb...

independent from any timing benefits: it will help to prevent users  
to use more than the one granted slot. Some parallel libs are just  
forking or using threads and don't need any qrsh to spawn a parallel  
job. Nasty users can just use OpenMP with a thread count greater than  
1 for now.

-- Reuti
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