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Re: [RFC] build with OpenMP by default?
From: |
Mike Miller |
Subject: |
Re: [RFC] build with OpenMP by default? |
Date: |
Wed, 23 Apr 2014 08:18:46 -0400 |
On Wed, Apr 23, 2014 at 3:49 AM, Susi Lehtola wrote:
> Still, talking about enabling OpenMP without anything in Octave that
> actually uses OpenMP is pretty much senseless... First one would have
> to implement parallellism, then test it and then talk about enabling it
> as a default.
If you didn't glance at the motivating bug report, here's a motivating
example that shows why I brought up enabling OpenMP by default:
octave:1> im = imread ("large_image.tif");
octave:2> clear -f
octave:3> system ("pwd");
/home/mike
panic: Segmentation fault -- stopping myself...
attempting to save variables to 'octave-workspace'...
save to 'octave-workspace' complete
Enabling OpenMP in Octave, whether or not Octave itself uses it,
enables using OpenMP in oct-files. Without it, oct-files that do use
OpenMP (or use OpenMP-enabled libraries) can crash Octave. This
problem exists in 3.8.1 now, the GraphicsMagick library uses OpenMP.
I've just opened https://savannah.gnu.org/bugs/?42176, for which my
fix will be to enable OpenMP by default as I proposed in this thread.
Please comment there if you have thoughts on how to solve this problem
without linking Octave with OpenMP by default.
--
mike