Is there a way to assign one thread to one core? Also from code, not necessary with OpenMPI option.
Thanks. 2008/11/19 Stephen Wornom <stephen.wor...@sophia.inria.fr>: > Gabriele Fatigati wrote: >> >> Ok, >> but in Ompi 1.3 how can i enable it? >> > > This may not be relevant, but I could not get a hybrid mpi+OpenMP code to > work correctly. > 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 >>> series >>> >>> >>> On 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 >>> >>> >>> >> >> >> >> > > > -- > stephen.wor...@sophia.inria.fr > 2004 route des lucioles - BP93 > Sophia Antipolis > 06902 CEDEX > > Tel: 04 92 38 50 54 > Fax: 04 97 15 53 51 > > > _______________________________________________ > 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
