Re: Adding OpenMP support for some of the GSL functions

[Maxime Boissonneault <maxime.boissonneault@calculquebec.ca>]

Hi Rhys,
While that is true in theory, it is not applicable in practice, since 
there can be no "return" within parallel sections. We need one parallel 
section for each loop in this case.

Maxime

Le 2012-12-13 11:44, Rhys Ulerich a écrit :
>> This feels like you're getting a small
>> memory/cache bandwidth increase for the rkf45_apply level-1-BLAS-like
>> operations by using multiple cores but the cores are otherwise not
>> being used effectively.  I say this because a state vector 1e6 doubles
>> long will not generally fit in cache.  Adding more cores increases the
>> amount of cache available.
> Hmm... I tentatively take this back on re-thinking how you've added
> the #pragma omp lines to the rkf45.c file you attached elsewhere in
> this thread.  Try using a single
>      #pragma omp parallel
> and then individual lines like
>      #pragma omp for
> at each for loop.  Using
>      #pragma omp parallel for
> repeatedly as you've done can introduce excess overhead, depending on
> your compiler, because it may incur unnecessary overhead.
>
> - Rhys