[mesa-users] OpenMP vs. MPI

[Josiah Schwab]

Hi Ryan,

> Did you turn hyperthreading off in the bios when doing the test on <=4
> cores?  It depends on the code, compiler, problem, cpu, etc., but
> typically that is the more practical test for checking if
> hyperthreading is faster or slower.  I have do not recall my past
> tests with MESA, but I have had codes that show a 10-20% slowdown with
> hyperthreading turned on, but typically this manifested itself only by
> changing the bios setting*.  That is, you might find MESA runs faster
> on four cores with HT turned off than with 4 or 8 cores with HT turned
> on in the bios.

In the data shown on the plot, HT was always active.  But with HT off in
the bios the results were similar for 1-4 cores.

As you say, this sort of result is very dependent on the details.

Josiah