Hi Jody,

Have you tried turning off Hyper-Threading with the Processor Preference Pane?

The processor palette is include in the CHUD package when you installed the developer tools. It lives in /Developer/Extras/PreferencePanes;  launch it and it will get added to the system preferences.

Warner Yuen
Scientific Computing 
Consulting Engineer
Apple, Inc.

On Jul 11, 2009, at 9:00 AM, users-request@open-mpi.org wrote:


Message: 3
Date: Sat, 11 Jul 2009 07:56:08 -0700
From: Klymak Jody <jklymak@uvic.ca>
Subject: [OMPI users] Xgrid and choosing agents...
To: users@open-mpi.org
Message-ID: <A6282054-7BCC-4261-9822-AD080B5A68EA@uvic.ca>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes

Hi all,

Sorry in advance if these are naive questions - I'm not experienced in  
running a grid...

I'm using openMPI on 4  duo Quad-core Xeon xserves.  The 8 cores mimic  
16 cores and show up in xgrid as each agent having 16 processors.   
However, the processing speed goes down as the used processors exceeds  
8, so if possible I'd prefer to not have more than 8 processors  
working on each machine at a time.

Unfortunately, if I submit a 16-processor job to xgrid it all goes to  
"xserve03".  Or even worse, it does so if I submit two separate 8- 
processor jobs.  Is there anyway to steer jobs to less-busy agents?

I tried making a hostfile and then specifying the host, but I get:

/usr/local/openmpi/bin/mpirun -n 8 --hostfile hostfile --host  
xserve01.local ../build/mitgcmuv

Some of the requested hosts are not included in the current allocation  
for the
The requested hosts were:

so I assume --host doesn't work with xgrid?

Is a reasonable alternative to simply not use xgrid and rely on ssh?

Thanks,  Jody

Jody Klymak


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