[aspect-devel] Performance issue with Trilinos solver on Aspect

Timo Heister heister at clemson.edu
Sat Sep 14 08:57:20 PDT 2013

>> While when I enable it, the solver do use more
>> cores (also checked with top, multiple CPU used) but the solver works even
>> slower than the single thread build !!! I wonder if did something wrong in
>> the
>> configuration and you may give me some hint. Thanks.

We have not experimented with multithreading inside Trilinos and the
combination with deal.II. The big problem is that mixing Intel TBB
(what we are using) with OpenMP in a single program won't work as far
as I know. Both systems will mess with thread affinities and create
threads that are busy-waiting and hogging cores.
This is a big problem in the scientific computing community. For now I
recommend disabling OpenMP (export OMP_NUM_THREADS=1) and using MPI

Timo Heister

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