[petsc-dev] PETSc and threads

[Nystrom, William David]

So is there any schedule for the availability of the new PETSc thread model implementation?
My understanding is that the current thread implementation in PETSc is not even supported
by the PETSc Team and use of it is discouraged.  I'm interested in this capability for both
Sequoia and Trinity and have been thinking about making a PETSc interface to one of the
main LANL ASC codes.

Dave

--
Dave Nystrom
LANL HPC-5
Phone: 505-667-7913
Email: wdn at lanl.gov
Smail: Mail Stop B272
       Group HPC-5
       Los Alamos National Laboratory
       Los Alamos, NM 87545


________________________________________
From: petsc-dev-bounces at mcs.anl.gov [petsc-dev-bounces at mcs.anl.gov] on behalf of Jed Brown [jed at jedbrown.org]
Sent: Friday, January 09, 2015 8:44 AM
To: Mark Adams; Barry Smith
Cc: For users of the development version of PETSc
Subject: Re: [petsc-dev] PETSc and threads

Mark Adams <mfadams at lbl.gov> writes:
> No this is me.  They will probably have about 30K (2D linear FE) equations
> per 40 Tflop node.  10% (4 Tflops) is too much resources for 30K equations
> as it is.  No need to try utilize the GPU as far as I can see.

With multiple POWER9 sockets per node, you have to deal with NUMA and
separate caches.  The rest of the application is not going to do this
with threads, so you'll have multiple MPI processes anyway.  The entire
problem will fit readily in L2 cache and you have a latency problem on
the CPU alone.  Ask them to make neighborhood collectives fast.