#1886: Should update openmpi in F11 prior to final

[Fedora Release Engineering]

#1886: Should update openmpi in F11 prior to final
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  Reporter:  dledford         |       Owner:  rel-eng at lists.fedoraproject.org
      Type:  task             |      Status:  new                            
 Milestone:  Fedora 11 Final  |   Component:  koji                           
Resolution:                   |    Keywords:                                 
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Comment (by dledford):

 Actually, no.  Both lapack and blas are *not* MPI using apps (one, they
 don't even include a BuildRequires: on any mpi stack, and two neither one
 have a single invocation to MPI_init() in their source code, and without
 it they will never use MPI directly).

 Secondly, the MPI spec requires any app to call MPI_init() prior to using
 any MPI functions.  MPI_init() would have to be a forking function with
 some rather tricky hand offs of file descriptors in order to allow an
 application linked against an MPI library to run without a runtime
 environment.  Instead, every MPI or psuedo MPI implementation I know of,
 going all the way back to pvm and lam, have required a run time for their
 apps.  The run time took care of A) determining which machines in the
 cluster to run on and how many to run on, B) determining which copies of
 the app were at what tier, C) starting a copy of the runtime on all the
 target machines, D) creating all the connections between the target
 machines/apps, and E) finally forking and starting the app with all the
 connections already up and going so that the MPI_init() merely needs to
 find out what tier it is and how many connections it has and then go from
 there.  It is much easier to do this work *before* you fork off the target
 app than it is afterwards, hence why everyone does it via a run time and
 not by hooking MPI_init() and then trying to retrofit things onto an
 already running app.  So I don't see any MPI stack working without their
 runtime any time soon.

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Ticket URL: <https://fedorahosted.org/rel-eng/ticket/1886#comment:6>
Fedora Release Engineering <http://fedorahosted.org/rel-eng>
Release Engineering for the Fedora Project