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
