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Subject: [OMPI users] Hybrid program
From: Gabriele Fatigati (g.fatigati_at_[hidden])
Date: 2008-11-18 11:18:43


Dear OpenMPI developers,
i have a strange problem with mixed program MPI+OPENMP over OpenMPI
1.2.6. I'm using PJL TASK GEOMETRY in LSF Scheduler, setting 2 MPI
process every compute node, and 2 OMP threads per process. Using
paffinity and maffinity, i've noted that over every node, i have 2
thread that works 100%, and 2 threads doesn't works, or works very
few.

If i disable paffinity and maffinity, 4 threads works well, without
load imbalance.
I don't understand this issue: paffinity and maffinity should map
every thread over a specific core, optimizing the cache flow, but i
have this without settings there!

Can i use paffinity and maffinity in mixed MPI+OpenMP program? Or it
works only over MPI thread?

Thanks in advance.

-- 
Ing. Gabriele Fatigati
CINECA Systems & Tecnologies Department
Supercomputing  Group
Via Magnanelli 6/3, Casalecchio di Reno (BO) Italy
www.cineca.it                    Tel:   +39 051 6171722
g.fatigati_at_[hidden]