[Beowulf] MPI Processes + Auto Vectorization

amjad ali amjad11 at gmail.com
Mon Nov 30 22:14:13 PST 2009

perhaps I could not better ask my question.

My question is that if we do not have free cpu cores in a PC or cluster (all
cores are running MPI processes), still the auto-vertorization is
beneficial? Or it is beneficial only if we have some free cpu cores locally?


On Mon, Nov 30, 2009 at 5:50 PM, David N. Lombard <dnlombar at ichips.intel.com
> wrote:

> On Mon, Nov 30, 2009 at 01:24:34PM -0700, amjad ali wrote:
> > Hi,
> > Suppose we run a parallel MPI code with 64 processes on a cluster, say of
> 16 nodes. The cluster nodes has multicore CPU say 4 cores on each node.
> >
> > Now all the 64 cores on the cluster running a process. Program is SPMD,
> means all processes has the same workload.
> >
> > Now if we had done auto-vectorization while compiling the code (for
> example with Intel compilers); Will there be any benefit
> (efficiency/scalability improvement) of having code with the
> auto-vectorization? Or we will get the same performance as without
> Auto-vectorization in this example case?
> >
> > How can we really get benefit in performance improvement with
> Auto-Vectorization?
> Vectorization takes advantage of the processor's vector instructions to
> increase data-level parallelism.
> How much that benefits your code depends very much on your code; you would
> need to recompile your code and test.
> --
> David N. Lombard, Intel, Irvine, CA
> I do not speak for Intel Corporation; all comments are strictly my own.
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