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Date: Wed, 10 Mar 2010 09:03:17 -0700
From: RB <>
Subject: Re: Is JTR MPIrun can be optimized for more cores ?

On Wed, Mar 10, 2010 at 01:26,
<> wrote:
>  Here it is a new test with Magnum's advice :
> ------------------------------------------------------
> 1  core,  duration 40 mn : found 8676
> ------------------------------------------------------
> 2 cores, duration  20 mn : found 8207
> ------------------------------------------------------
> 4 cores, duration  10 mn : found 7886
> ------------------------------------------------------
> 8 cores, duration   5  mn : found 7189
> ------------------------------------------------------

This does serve to roughly illustrate the point, but is also a clear
indicator of the lack of communication between the individual
processes.  There is a lot of room for improvement.

The most accurate test would be to do an incremental run of a
character set you know will complete on a single core in a reasonable
timeframe.  Then, test the completion time (using 'time john ...' for
accuracy) of 2, 3, and 4-core runs.

Please be aware that the MPI patch by itself induces (as I recall)
10-15% overhead in a single-core run.  All runs you are only going to
do on a single processor should never have the MPI patch applied.

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