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

[LEI CHAI]

Hi Joseph,

Could you try disable the cpu affinity feature in mvapich/mvapich2, e.g.

mvapich2:
$ mpiexec -n 4 -env MV2_ENABLE_AFFINITY 0 ./a.out

or mvapich:
$ mpirun_rsh -np 4 VIADEV_ENABLE_AFFINITY=0 ./a.out

Thanks,
Lei


----- Original Message -----
From: Joseph Hargitai <joseph.hargitai at nyu.edu>
Date: Friday, January 18, 2008 6:05 pm
Subject: [mvapich-discuss] mpiexec/mvapich places processes on same cpu

> 
> 
> 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
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