Newsgroups: comp.parallel.mpi
From: patrick@walt.CS.MsState.Edu (Patrick G. Bridges)
Subject: Re: MPI for shared memory machines?
Organization: Mississippi State University CS Dept.
Date: 04 Aug 1994 18:12:23 GMT
Message-ID: <PATRICK.94Aug4131223@walt.CS.MsState.Edu>

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>>>>> "LB" == Luis Barriga <luis@quipu.electrum.kth.se> writes:
In article <LUIS.94Aug4191334@quipu.electrum.kth.se> luis@quipu.electrum.kth.se (Luis Barriga) writes:


    LB> (I saw FAQ and coudn't find an answer to the following
    LB> question) I will soon develop parallel software on a Sun
    LB> multiprocessor with shared memory (S-2000). Initially, for
    LB> portability reasons, it was planned to use the P4 package but
    LB> somebody suggested to use MPI instead. P4 supports both models
    LB> message-passing and shared-memory, but it seems that MPI only
    LB> supports message-passing. Is that right?

MPI is a message passing standard, and, as such, supports only message
passing semantics. However, implementations are free to use whatever
technique they want to implement message passing semantics. The
refrence implementation from Argonne and Mississippi State can sit on
top of p4 (this is the prefered device for workstation clusters) and
use p4's shared memory for message passing. This requires changing the
options P4 is compiled with to define SYSV_IPC. (The file to set this
is in the top level p4 directory, which is mpich/mpid/ch_p4/p4-1.4 in
the ANL/MSU implementation. The file is called, of all things, OPTIONS) 

Honestly, we don't usually use the shared memory version on the
Suns or SGIs, just because SYSV is, IMHO, such a kludge. Still it
should work.  If it doesn't report it as a bug...

    LB> BTW, from all available implementations of MPI, does any of
    LB> them run on Solaris 2.x?

I don't know about the others, but Argonne/MSU implementation 
can when configured with :

configure -arch=solaris -device=ch_p4

(add -mpe for MPE extensions, -nof77 if you don't have fortran)

Or at least it did last I checked... :-) If it doesn't, report the
problems and they should get fixed ASAP.  Report bugs in the Argonne
implementation (which is available from ftp.mcs.anl.gov:/pub/mpi) to
mpi-bugs@mcs.anl.gov.



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