[petsc-users] A bad commit affects MOOSE

[Matthew Knepley]

On Tue, Apr 3, 2018 at 6:06 PM, Jed Brown <jed at jedbrown.org> wrote:

> Derek Gaston <friedmud at gmail.com> writes:
>
> > Sounds great to me - what library do I download that we're all going to
> use
> > for managing the memory pool?  :-)
> >
> > Seriously though: why doesn't MPI give us an ability to get unique tag
> IDs
> > for a given communicator?
>
> It's called a dup'd communicator.
>
> > I like the way libMesh deals with this:
> > https://github.com/libMesh/libmesh/blob/master/include/
> parallel/parallel_implementation.h#L1343
>
> PETSc does something similar, but using attributes inside the MPI_Comm
> instead of as a wrapper that goes around the communicator.
>
> https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/
> PetscCommGetNewTag.html
>
> > I would definitely sign on for all of us to use the same library for
> > getting unique tag IDs... and then we would need a lot less
> communicators...
>
> Communicators should be cheap.  One per library per "size" isn't a huge
> number of communicators.
>

And this
https://experts.illinois.edu/en/publications/mpi-on-millions-of-cores still
got published? I guess
the reviewers never wanted any more than 2K communicators ;)

   Matt

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>
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