Hi Claudio Check 'man mpirun'. You will find examples of the '-byslot', '-bynode', '-loadbalance', and rankfile options, which allow some control of how ranks are mapped into processors/cores.
I hope this helps, Gus Correa On Mar 1, 2012, at 2:34 PM, Claudio Pastorino wrote: > Hi, thanks for the answer. > You are right is not the rank what matters but how do I arrange > the physical procs in the cartesian topology. I don't care about the label. > So, how do I achieve that? > > Regards, > Claudio > > > > 2012/3/1, Ralph Castain <r...@open-mpi.org>: >> Is it really the rank that matters, or where the rank is located? For >> example, you could leave the ranks as assigned by the cartesian topology, >> but then map them so that ranks 0 and 2 share a node, 1 and 3 share a node, >> etc. >> >> Is that what you are trying to achieve? >> >> >> On Mar 1, 2012, at 11:57 AM, Claudio Pastorino wrote: >> >>> Dear all, >>> I apologize in advance if this is not the right list to post this. I >>> am a newcomer and please let me know if I should be sending this to >>> another list. >>> >>> I program MPI trying to do HPC parallel programs. In particular I >>> wrote a parallel code >>> for molecular dynamics simulations. The program splits the work in a >>> matrix of procs and >>> I send messages along rows and columns in an equal basis. I learnt >>> that the typical >>> arrangement of cartesian topology is not usually the best option, >>> because in a matrix, let's say of 4x4 procs with quad procs, the >>> procs are arranged so that >>> through columns one stays inside the same quad proc and through rows >>> you are always going out to the network. This means procs are >>> arranged as one quad per row. >>> >>> I try to explain this for a 2x2 case. The cartesian topology does this >>> assignment, typically: >>> cartesian mpi_comm_world >>> 0,0 --> 0 >>> 0,1 --> 1 >>> 1,0 --> 2 >>> 1,1 --> 3 >>> The question is, how do I get a "user defined" assignment such as: >>> 0,0 --> 0 >>> 0,1 --> 2 >>> 1,0 --> 1 >>> 1,1 --> 3 >>> >>> ? >>> >>> Thanks in advance and I hope to have made this more or less >>> understandable. >>> Claudio >>> _______________________________________________ >>> 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 >> > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
