[mpich-discuss] MPICH2 and Process Affinity

[Pavan Balaji]

> 1. Is there a similar way in MPICH2 or I have to use 
> SetProcessAffinityMask() in Windows to pin all my MPI processes to the 
> specific logical processor/core ?
>     (If a process is pinned to a specific logical processor, the CPU 
> loading histroy from the Windows task manager is smoother rather than 
> lots of zigzags.)

Not right now, but its planned to be added in the mpich2-1.1 release. 
Microsoft's modification to MPICH2 (called MS-MPI) already has this 
support, if you want to try it out sooner 
(http://www.microsoft.com/hpc). I don't know if it's free though :-).

> 2. Does the process migration cause large penalty in parallel computing ?

I know that Linux gives "preference" to keep processes on the same core 
when there are equal number of processes and cores. This is not the same 
thing as binding, but it's close to it. Windows probably does something 
similar too, but I'm not really sure.

  -- Pavan

-- 
Pavan Balaji
http://www.mcs.anl.gov/~balaji