[petsc-users] Streams scaling.log

Wed Apr 25 14:34:24 CDT 2018

I get it, thanks, that's a strong argument i will tell my advisor about

Have a great day,

On Wed, Apr 25, 2018 at 12:30 PM, Smith, Barry F. <bsmith at mcs.anl.gov>
wrote:

>
>
> > On Apr 25, 2018, at 2:12 PM, Manuel Valera <mvalera-w at sdsu.edu> wrote:
> >
> > Hi and thanks for the quick answer,
> >
> > Yes it looks i am using MPICH for my configure instead of using the
> system installation of OpenMPI, in the past i had better experience using
> MPICH but maybe this will be a conflict, should i reconfigure using the
> system MPI installation?
> >
> > I solved the problem in a different way by login into the nodes i wanted
> to use and doing the make streams tests there, but i get the following:
> >
> > np  speedup
> > 1 1.0
> > 2 1.51
> > 3 2.17
> > 4 2.66
> > 5 2.87
> > 6 3.06
> > 7 3.44
> > 8 3.84
> > 9 3.81
> > 10 3.17
> > 11 3.69
> > 12 3.81
> > 13 3.26
> > 14 3.51
> > 15 3.61
> > 16 3.81
> > 17 3.8
> > 18 3.64
> > 19 3.48
> > 20 4.01
> >
> > So very modest scaling, this is about the same i get with my
> application, how can i make it work faster?
>
>    You can't, the memory bandwidth is the limiting factor on this machine
> (not the number of cores) and there is nothing to be done about it. When
> buying machines make sure that the memory bandwidth is an important factor
> in the decision.
>
>   Barry
>
>
> > i am already using --map-by and --machinefile arguments for mpirun,
> maybe this is also a conflict with the different MPI installations?
> >
> > Thanks,
> >
> >
> >
> > On Wed, Apr 25, 2018 at 11:51 AM, Karl Rupp <rupp at iue.tuwien.ac.at>
> wrote:
> > Hi Manuel,
> >
> > this looks like the wrong MPI gets used. You should see an increasing
> number of processes, e.g.
> >
> > Number of MPI processes 1 Processor names  node37
> > Triad:         6052.3571   Rate (MB/s)
> > Number of MPI processes 2 Processor names  node37 node37
> > Triad:        9138.9376   Rate (MB/s)
> > Number of MPI processes 3 Processor names  node37 node37 node37
> > Triad:        11077.5905   Rate (MB/s)
> > Number of MPI processes 4 Processor names  node37 node37 node37 node37
> > Triad:        12055.9123   Rate (MB/s)
> >
> > Best regards,
> > Karli
> >
> >
> >
> >
> > On 04/25/2018 08:26 PM, Manuel Valera wrote:
> > Hi,
> >
> > I'm running scaling tests on my system to check why my scaling is so
> poor, and after following the MPIVersion guidelines my scaling.log output
> looks like this:
> >
> > Number of MPI processes 1 Processor names  node37
> > Triad:        12856.9252   Rate (MB/s)
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Triad:         9138.3320   Rate (MB/s)
> > Triad:         9945.0006   Rate (MB/s)
> > Triad:        10480.8471   Rate (MB/s)
> > Triad:        12055.4846   Rate (MB/s)
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Triad:         7394.1014   Rate (MB/s)
> > Triad:         5528.9757   Rate (MB/s)
> > Triad:         6052.7506   Rate (MB/s)
> > Triad:         6188.5710   Rate (MB/s)
> > Triad:         6944.4515   Rate (MB/s)
> > Triad:         7407.1594   Rate (MB/s)
> > Triad:         9508.1984   Rate (MB/s)
> > Triad:        10699.7551   Rate (MB/s)
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Number of MPI processes 1 Processor names  node37
> > Triad:         6682.3749   Rate (MB/s)
> > Triad:         6825.3243   Rate (MB/s)
> > Triad:         7217.8178   Rate (MB/s)
> > Triad:         7525.1025   Rate (MB/s)
> > Triad:         7882.1781   Rate (MB/s)
> > Triad:         8071.1430   Rate (MB/s)
> > Triad:        10341.9424   Rate (MB/s)
> > Triad:        10418.4740   Rate (MB/s)
> >
> >
> > Is this normal? i feel is different from what i get from an usual
> streams test, how can i get it to work properly?
> >
> > Thanks,
> >
> >
> >
> >
> >
>
>
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