Re: Multithreaded FFTW3 in octave?

[Mike Miller]

On Wed, Dec 12, 2012 at 8:30 AM, John W. Eaton wrote:
> On 12-Dec-2012, Andreas Weber wrote:
>
> | Dear maintainers,
> |
> | Why does octave not use the multithreaded FFTW3 libs or am I missing a
> | configure flag?
>
> Because no one has done the work for it?
>
> [...]
>
> That looks like a nice performance improvement.  Would you like to
> propose a complete patch that

Yeah, I like the sound of this additional option, thanks for bringing
it to our attention. If you do plan on working on it please keep us
updated, or least me, I'm interested in trying this out. If you don't
work on it, I may get to it at some point, I could use this. Also if
you don't plan on working on it, feel free to submit it as a feature
request at http://bugs.octave.org/

>   * makes the number of threads configurable by the user (probably by
>     adding a new fftw_max_nthreads function or similar)

How about adding an extra option to the existing fftw interpreter
function? Something like

octave:1> fftw ("threads")
ans = 1
octave:2> fftw ("threads", 8)

>   * documents the new configuration function
>
>   * adds a configure test for this feature (unless it can be assumed
>     to be present in every reasonable FFTW installation today) and
>     checks for the necessary library

Yes, definitely needs a configure test. I did a quick test and these
threading functions are not in my self-compiled FFTW library. There
are apparently fftw3_threads and fftw3_omp variants that you have to
link with instead of the normal fftw3 library.

--
mike