On Feb 3, 2011, at 8:33 PM, Jed Brown wrote:
> Try telling your MPI to run each process on different sockets, or on the same
> socket with different caches. This is easy with Open MPI and with
> MPICH+Hydra. You can simply use taskset for serial jobs.
We should add this options to the FAQ.html memory bandwidth question for
everyone to easily look up.
Barry
>
>
>> On Feb 3, 2011 5:46 PM, "Barry Smith" <bsmith at mcs.anl.gov> wrote:
>>
>>
>> Based on these numbers (that is assuming these numbers are a correct
>> accounting of how much memory bandwidth you can get from the system*) you
>> essentially have a one processor machine that they sold to you as a 8
>> processor machine for sparse matrix computation. The one core run is using
>> almost all the memory bandwidth, adding more cores in the computation helps
>> very little because it is completely starved for memory bandwidth.
>>
>> Barry
>>
>> * perhaps something in the OS is not configured correctly and thus not
>> allowing access to all the memory bandwidth, but this seems unlikely.
>>
>> On Feb 3, 2011, at 4:29 PM, Vijay S. Mahadevan wrote:
>>
>> > Barry,
>> >
>> > The outputs are attached. I do...
>>
>> > <basicversion_np1.out><basicversion_np2.out>
>>
>
