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

[JohnD]

> Message: 2
> Date: Mon, 14 Dec 2015 13:10:04 -0500
> From: Mike Miller <address@hidden>
> To: address@hidden
> Subject: Re: Perfromance problem running multiple copies of Octave on
>       a       multicore processor
> Message-ID: <address@hidden>
> Content-Type: text/plain; charset=utf-8
> 
> 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
> 
> 

It was probably changed from this: https://savannah.gnu.org/bugs/?43525