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Subject: Re: [OMPI devel] barrier problem
From: Ralph Castain (rhc_at_[hidden])
Date: 2012-03-23 08:55:52


I don't see where you told OMPI to --bind-to-core. We don't automatically bind, so you have to explicitly tell us to do so.

On Mar 23, 2012, at 6:20 AM, Pavel Mezentsev wrote:

> Hello
>
> I'm doing some testing with IMB and dicovered a strange thing:
>
> Since I have a system with new AMD opteron 6276 processors I'm using 1.5.5rc3 since it supports binding to cores.
>
> But when I run the barrier test form intel mpi benchmarks, the best I get is:
> #repetitions t_min[usec] t_max[usec] t_avg[usec]
> 598 15159.56 15211.05 15184.70
> (/opt/openmpi-1.5.5rc3/intel12/bin/mpirun -x OMP_NUM_THREADS=1 -hostfile hosts_all2all_2 -npernode 32 --mca btl openib,sm,self -mca coll_tuned_use_dynamic_rules 1 -mca coll_tuned_barrier_algorithm 1 -np 256 openmpi-1.5.5rc3/intel12/IMB-MPI1 -off_cache 16,64 -msglog 1:16 -npmin 256 barrier)
>
> And with openmpi 1.5.4 the result is much better:
> #repetitions t_min[usec] t_max[usec] t_avg[usec]
> 1000 113.23 113.33 113.28
>
> (/opt/openmpi-1.5.4/intel12/bin/mpirun -x OMP_NUM_THREADS=1 -hostfile hosts_all2all_2 -npernode 32 --mca btl openib,sm,self -mca coll_tuned_use_dynamic_rules 1 -mca coll_tuned_barrier_algorithm 3 -np 256 openmpi-1.5.4/intel12/IMB-MPI1 -off_cache 16,64 -msglog 1:16 -npmin 256 barrier)
>
> and still I couldn't come close to the result I got with mvapich:
> #repetitions t_min[usec] t_max[usec] t_avg[usec]
> 1000 17.51 17.53 17.53
>
> (/opt/mvapich2-1.8/intel12/bin/mpiexec.hydra -env OMP_NUM_THREADS 1 -hostfile hosts_all2all_2 -np 256 mvapich2-1.8/intel12/IMB-MPI1 -mem 2 -off_cache 16,64 -msglog 1:16 -npmin 256 barrier)
>
> I dunno if this is a bug or me doing something not the way I should. So is there a way to improve my results?
>
> Best regards,
> Pavel Mezentsev
>
>
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