Discussion related to cado-nfs

[Emmanuel Thomé <Emmanuel.Thome@inria.fr>]

On Thu, Jan 07, 2016 at 09:01:12AM +0100, Paul Zimmermann wrote:
>        Rob,
> 
> > Using bridged networking and 8 MIC co-processors, hybrid Xeon and Xeon
> > Phi execution is feasible.  Ten factor trials of RSA-120 finished in
> > under 2 hours.
> > (1.6337+1.6400+1.6357+1.7245+1.6255+1.7062+1.6105+1.6214+1.6021+1.6321)/10=1.64317
> > hrs
> 
> I've just added timings on http://cado-nfs.gforge.inria.fr/ with 2.2.0:
> on a dual 8-core Intel(R) Xeon(R) CPU E5-2650 at 2.00GHz, factoring
> RSA-120 with CADO-NFS 2.2.0 takes about 2.2 hours of wall clock time
> (32.2 hours of cpu time). You used about 1200 hours cpu.
> 
> > 1.) Will MPI enable utilization of the 1920 MIC cores for linalg?
> 
> I let Emmanuel answer to that.

probably, yes. Depends on which mpi implementation you intend to use. But
one may imagine that with proper mpi incantations, you may run one thread
per MIC core.

This would mean passing mpi=48x40 to bwc.pl, and pass in mpi_extra_args
all the stuff needed to address the MIC cores. Which I have absolutely no
clue about.

I doubt this will be very efficient, though.

E.