[Wrf-users] SMPar and DMPar

[Gerardo Cisneros]

On Mon, 18 Aug 2008, jcrosby wrote:
> I was wondering if someone could tell me the difference between Serial, 
> SMPar and DMPar compiles of WRF and the Post Processors.
> 
> As far as I can figure out Serial is for single CPUs, SMPar is for 
> multi-core/Multi CPUs and DMPar is for Clusters.  Would this be accurate?

You're right about "Serial".  What you get is
an executable that will only run on a single
processor (or core).

"SMPar" means "Shared-Memory Parallelism"; in
practice what happens is that OpenMP directives
are enabled and the resulting binary will only
run within a single shared-memory system.

"DMPar" means "Distributed-Memory Parallelism",
which in turn means MPI will be used in the
build.  The resulting binary will run within
and across multiple nodes of a distributed-
memory system, better known these days as a
cluster.

You can also configure for a build that includes
both SMPar and DMPar; the resulting binary can
be run hybrid, meaning using OpenMP for parallelism
within nodes (total or partial) and MPI across nodes.
Getting a hybrid build to have its OpenMP threads
and MPI tasks placed properly on the processors can
tricky, though.

Saludos,

Gerardo
-- 
Dr. Gerardo Cisneros	|SGI (Silicon Graphics, S.A. de C.V.)
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