[mpich-discuss] MPICH2 CPUs Vs. Cores

[Peter Willis]

On 7/15/2011 2:50 PM, Reuti wrote:
> Hi,
>
> Am 15.07.2011 um 23:34 schrieb Peter Willis:
>
>> I have a single system with 4 CPUs. Each CPU has 12 cores.(48 cores total)
>> MPICH2 is built and installed from source and there are no errors.
>>
>> The documentation is a bit vague regarding CPUs  vs. Cores.
>>
>> QUESTIONS:
>>
>> 1.)
>> What is the best way for a single node system to utilize
>> a maximum number of cores?
>
> what do you mean by this in detail? Do your applications scale well with increasing number granted cores?
>

The code we are running scales well to 128 CPUs.

We have contact with another user who has a cluster with
several machines, 4 cores each machine. They run 64 cores
total.

Our system is only one machine with 48 cores. It currently
only utilizes 4 cores of the 48. In fact the system gives
a segfault if  mpiexec -n  is greater than 4. (?...)

I am trying to deduce if there is a compilation problem,
a run-time parameter problem, or a process management problem.

Peter