Gabriele Fatigati wrote:
This may not be relevant, but I could not get a hybrid mpi+OpenMP code to work correctly.Ok, but in Ompi 1.3 how can i enable it?
Would my problem be related to Gabriele's and perhaps fixed in openmpi 1.3? Stephen
2008/11/18 Ralph Castain <r...@lanl.gov>:I am afraid it is only available in 1.3 - we didn't backport it to the 1.2 seriesOn Nov 18, 2008, at 10:06 AM, Gabriele Fatigati wrote:Hi, how can i set "slot mapping" as you told me? With TASK GEOMETRY? Or is a new 1.3 OpenMPI feature? Thanks. 2008/11/18 Ralph Castain <r...@lanl.gov>:Unfortunately, paffinity doesn't know anything about assigning threads to cores. This is actually a behavior of Linux, which only allows paffinity to be set at the process level. So, when you set paffinity on a process, you bind all threads of that process to the specified core(s). You cannot specify that a thread be given a specific core. In this case, your two threads/process are sharing the same core and thus contending for it. As you'd expect in that situation, one thread gets the vast majority of the attention, while the other thread is mostly idle. If you can upgrade to the beta 1.3 release, try using the slot mapping to assign multiple cores to each process. This will ensure that the threads for that process have exclusive access to those cores, but will not bind a particular thread to one core - the threads can "move around" across the specified set of cores. Your threads will then be able to run without interfering with each other. Ralph On Nov 18, 2008, at 9:18 AM, Gabriele Fatigati wrote: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.fatig...@cineca.it _______________________________________________ users mailing list us...@open-mpi.org http://www.open-mpi.org/mailman/listinfo.cgi/users_______________________________________________ users mailing list us...@open-mpi.org http://www.open-mpi.org/mailman/listinfo.cgi/users-- 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.fatig...@cineca.it _______________________________________________ users mailing list us...@open-mpi.org http://www.open-mpi.org/mailman/listinfo.cgi/users_______________________________________________ users mailing list us...@open-mpi.org http://www.open-mpi.org/mailman/listinfo.cgi/users
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