[mpich-discuss] MPICH2 CPUs Vs. Cores

[Reuti]

Am 16.07.2011 um 00:18 schrieb 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. (?...)

Are all 4 cores allocated on one and the same CPU?

What about a simple mpihello - is this running well with more than 4 cores?

Running across more than one machine might give more memory in total - depends. What has the other cluster per node and your machine in total?

-- Reuti


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