[mvapich-discuss] mpiexec/mvapich places processes on same cpu

[Joseph Hargitai]

hi all:

While submitting two identical mpi jobs (-np 4) with differetnt datasets for a dual socket quadocore node using two distinct pbs/mpiexec submission both jobs end up on the first processor, such they use 4 cores of the first cpu, none of the second. This results in 8 processes on cpu 1, with a load of about 8-9, both jobs producing output okay, but obviously the choice would be to have them on distinct cpus. 

When one of these mpi jobs meet 4 others regular serial jobs submitted without mpiexec, all 8 cores are populated. 

I did read on the group list about the first mpiexec session being the master, but not reserving the first 4 cores such allowing the possibility for the next mpi job to end up on the same cpu. 

best,   
joseph