[Users] Possible performance issue

Mon Oct 7 10:56:14 CDT 2019

Dear Sir,

Please find the config-info file attached herewith...

Yours,

Vaishak

On Mon, Oct 7, 2019 at 7:56 PM Haas, Roland <rhaas at illinois.edu> wrote:

> Hello Vaishak,
>
> hmm, still very slow.
>
> One question that I forgot to ask before: did you make sure to build
> and optimized Cactus executable (setting OPTIMISE=yes, DEBUG=no to
> ensure that you have -O2 or -O3 optimisation settings enabled)?
>
> Ideally if you could send the file configs/sim/config-info that would
> tell me.
>
> Yours,
> Roland
>
> > Dear Sir,
> >
> > I am a little worried about the performance because this is a new cluster
> > we have and it is supposed to be performing well. I am inclined to think
> > that some libraries/compiler options / settings might be the bottleneck.
> >
> >
> > I am presently running two simulations, both using the same parameter
> file
> > GW150914.rpar.
> >
> > The first one is using mpich-3.3.1, the same as in the simulation
> mentioned
> > in the previous thread. I am using one node consisting of 2*16 cores, and
> > 32 mpiprocs.
> >
> > The second one is using openmpi-3.1.2 with openmp. It uses 128 procs,
> > distributed among 16 mpiprocs and 8 openmp threads per mpiproc. Since I
> > have 32 PPN, it is launching 4 mpiprocs per node.
> >
> > I am herewith attaching the carpet-timing..asc file from both these runs.
> >
> > Thanking you
> >
> > Regards,
> > Vaishak
> >
> >
> > On Fri, Oct 4, 2019 at 8:05 PM Haas, Roland <rhaas at illinois.edu> wrote:
> >
> > > Hello Vaishak,
> > >
> > > I do not see anything obviously wrong with the setup.
> > >
> > > It uses 128 MPI ranks for the 4 nodes which fits with there being 2x16
> > > cores per node.
> > >
> > > Lookin at the timer tree output at iteration 1024 (search for
> > > "gettimeof " and you will find the spot) out of 5977s spend during
> > > Evolve about 2143s were spent in "syncs" which is communication and
> > > about the same amount of time in "thorns" that is doing computation.
> > > While this ratio is not great (spending more time sending data than
> > > doing computation) it is also not unheard of.
> > >
> > > Getting the original output files for the gallery data from Zenodo
> > > (link is on the gallery page):
> > >
> > > wget
> > > https://zenodo.org/record/155394/files/GW150914_28.tar.xz?download=1
> > >
> > > you can see (in GW150914_28/output-0000/GW150914_28.out) that that one
> > > took about 137s for syncs and 198s for thorns, so the same ratio but
> > > about a factor of 10 faster.
> > >
> > > I am reaching for straws here, but sometimes having too many MPI ranks
> > > can be detrimental if there is not enough work to split up (OpenMP can
> > > be a bit more forgiving in that respect, the original gallery run
> > > used 120 cores on 10 nodes using 6 OpenMP threads per MPI rank).
> > >
> > > Since each node has lots of RAM (more than the 96GB required to run the
> > > simulation), can you try and see what would happen if you were to run
> > > on only a single node?
> > >
> > > Also if you could add the parameter:
> > >
> > > Carpet::output_timers_every = 1024
> > >
> > > then provide the files carpet-timing-statistics*.asc that would let us
> > > know in even more detail where the time is spent.
> > >
> > > Running for a short time (2048 iterations) is enough to get data to
> > > compare.
> > >
> > > Yours,
> > > Roland
> > >
> > > > Dear All,
> > > >
> > > > I am running the simulation GW150914 using the parameter file
> available
> > > at
> > > > the ETK gallery at (GW150914-ETK gallery
> > > > <https://einsteintoolkit.org/gallery/bbh/index.html>) using 128
> cores.
> > > >
> > > > Each compute node consists of 2 X 16 Cores Intel SkyLake ( Intel(R)
> > > Xeon(R)
> > > > Gold 6142 CPU @ 2.60GHz) and 384 GB RAM .  I have compiled and am
> running
> > > > Einstein Toolkit without OpenMP and using mpich-3.3.1.
> > > >
> > > >
> > > > The issue is that the simulation seems to be running at a very slow
> pace.
> > > > The number of physical time per hour that it is completing is only
> about
> > > > 1.3 units. At this rate to complete 1700 units, it would take about
> 54
> > > > days, in contrast to 2.8 days on (Intel(R) Xeon(R) CPU E5-2630 v3 @
> > > > 2.40GHz) as per the details at the example run of GW150914 available
> at
> > > the
> > > > gallery (GW150914-ETK gallery
> > > > <https://einsteintoolkit.org/gallery/bbh/index.html>).
> > > >
> > > > I have also tried using intel mpi (impi) but with simular results.
> > > >
> > > > I am also attaching the out file from the simulation.
> > > >
> > > > Looking forward to your inputs.
> > > >
> > > >
> > > > Thanks and regards,
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Vaishak P
> > > >
> > > > PhD Scholar,
> > > > Shyama Prasad Mukherjee Fellow
> > > > Inter-University Center for Astronomy and Astrophysics (IUCAA)
> > > > Pune, India
> > >
> > >
> > >
> > > --
> > > My email is as private as my paper mail. I therefore support encrypting
> > > and signing email messages. Get my PGP key from http://pgp.mit.edu .
> > >
> >
> >
>
>
>
> --
> My email is as private as my paper mail. I therefore support encrypting
> and signing email messages. Get my PGP key from http://pgp.mit.edu .
>

-- 
Regards,
Vaishak P

PhD Scholar,
Shyama Prasad Mukherjee Fellow
Inter-University Center for Astronomy and Astrophysics (IUCAA)
Pune, India
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