Newsgroups: comp.parallel.mpi
From: gropp@godzilla.mcs.anl.gov (William Gropp)
Subject: Re: Bcast impmelmentation on SP2/mpich
Organization: MCS, Argonne National Laboratory
Date: Fri, 17 Apr 1998 21:42:11 GMT
Message-ID: <8928493318659@godzilla.mcs.anl.gov>

In article <35350E75.C0C490D1@ecs.soton.ac.uk>,
Panagiotis Melas  <pm95r@ecs.soton.ac.uk> wrote:
>Does anybody know whether the broadcast implementation of MPI Bcast is
>based on a binomial tree or not for the IBM SP2?

The MPICH implementation can be found in mpich/src/coll/intra_fns.c .
The algorithm uses recursive subdivision; the root will send log_2(size of
communicator) times.  The algorithm does not pipeline, nor is it tuned to 
particular systems or message sizes.  Making the algorithms more 
sophisticated has been on our list-of-things-to-do for some time, but 
are currently lower priority to the MPI-2 implementation.

Bill