[Users] OpenMP now used by default in Simfactory

[Erik Schnetter]

Dear Einstein Toolkit users

Up until now, Simfactory did not use OpenMP by default. That is, even
if a code was built with OpenMP, Simfactory would by default use only
a single thread when submitting a job, and parallelise purely via MPI
instead. This reflected the state of the thorns, as several key thorns
could in the past not make efficient use of OpenMP.

This has changed, and e.g. the recent release of the Einstein Toolkit
contains efficient OpenMP-parallelised implementations of the BSSN and
GR-MHD equations, and all other key thorns. To our knowledge, most
people use OpenMP for most of their production runs.

We therefore now proudly announce that we are enabling OpenMP in job
submissions by default. Simfactory "knows" what a good number of
OpenMP threads is for most machines. This number depends on the
hardware architecture, and thus differs from machine to machine, and
Simfactory will use that many threads by default. You can override
this via the --num-threads=... option; using a single thread will
effectively disable OpenMP.

I assume that this "good" number of threads described in Simfactory
may require some adjustment in some cases. Please report cases where
you think that Simfactory is mis-behaving.

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>   http://www.cct.lsu.edu/~eschnett/