Newsgroups: comp.parallel.mpi
From: don schad <dschad@frontiernet.net>
Subject: multi-cpu machines and mpi
Organization: Frontier Internet Rochester N.Y. (716)-777-SURF
Date: 18 Aug 1998 17:47:12 GMT
Message-ID: <6rcen0$qju$1@node17.cwnet.frontiernet.net>

hi,

we are currently looking to invest in computer
equipment to develop a beowulf-type multi-computer
and convert existing computer models to work on
this system. the parallelization of the code will (likely)
be through the MPI libraries. the question came up 
as to whether we should purchase (N/2) two-processor
intel machines or N single-processor machines.  i
am trying to acess the advantages/disadvantages
of using the networked multi-processor machines vs
twice as many single-processor machines.

from this i have a fairly basic question, for which
i have been unable to find the answer on the web or
FAQ's:

does MPI directly support multiple cpus in one machine,
or does one simply create multiple processes on the
same host to take advantage of the cpu's?  if the latter is
the case, is the overhead  [essentially] the same
as if these two processes were running on two different
networked machines (assuming we have independent buses
for each processor, two ethernet cards, etc) ?  can we 
speed things up using either hardware or software 
configuration (i.e. using route or something)? 

i very much appreciate any and all input, comments and
suggestions.

thank you,

don schad
hydroqual, inc.