Re: Perfromance problem running multiple copies of Octave on a multicore processor

[Mike Miller]

On Mon, Dec 14, 2015 at 16:54:38 +0000, Ian McCallion wrote:
> Hi Olaf and Mike,
> 
> Thank you both for your help. I have now worked out in more detail
> what has been happening to cause anomalous performance between Octave
> 3.8.2 and Octave 4.0.0 in my signal processing system:
> 
>      Octave 3.8.2 and earlier releases, with the supplied openblas
>      and lapack, only ever used a single thread, whether by design
>      or accident and whatever value (or none) at all was set for
>          OPENBLAS_NUM_THREADS
> 
>     This was changed/fixed in Octave 4.0.0.
> 
> I did not find any reference to this change in the documentation, and
> it may be worth adding a few lines in news to explain this.

I'm glad you were able to work out the problem with your system.

This change, if true, is likely due to either the way OpenBLAS is built
for the Octave 4.0.0 bundle, or the version of OpenBLAS that is now
used, or perhaps that OpenBLAS was not even present or being used in the
earlier release that you were running.

I don't know if we currently have a place to document changes or release
notes specific to the binary packaging of Octave for Windows, maybe we
should.

-- 
mike