Control: found -1 0.2.8-4 Control: tags -1 + wontfix Le dimanche 22 décembre 2013 à 20:15 +0100, Michael Banck a écrit : > On Wed, Aug 08, 2012 at 05:58:35PM -0400, Steven G. Johnson wrote: > > Currently, Debian installs the version of OpenBLAS that uses pthreads > > parallelism. In addition to this, or perhaps instead of this, it would > > be nice to have a version that uses OpenMP parallelism (compile with > > USE_OPENMP=1).
In 0.2.8-3, I had switched OpenBLAS to OpenMP, as you had requested. However, it turned out that this change caused several problems. See #737675 and https://github.com/xianyi/OpenBLAS/issues/294 for some examples. I have therefore reverted to pthreads in 0.2.8-4. Fundamentally, there seems to be a design problem when mixing OpenMP features with forks, at least with GCC. See http://bisqwit.iki.fi/story/howto/openmp/#OpenmpAndFork The discussion of a possible fix at the GCC level is discussed there: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60035 For the time being, the only safe solution is to have OpenBLAS compiled with pthreads. I therefore mark this bug as wontfix. This decision could be later revised if the issue with GCC is fixed. So if you want an OpenMP version of OpenBLAS, the easiest way is to create a custom build (as explained in README.Debian), adding the USE_OPENMP=1 flag in debian/rules. > Besides, I get very noisy warnings when building the newest (hybrid > MPI/OpenMP) version of MolDS, which uses OpenBLAS: > > OpenBLAS Warning : Detect OpenMP Loop and this application may hang. > Please rebuild the library with USE_OPENMP=1 option. > > There's more than one million of them while running the test suite, > which seriously bloats the build log. So at least it would be nice to > rate-limit or patch out this warning. Michael: to mitigate your problems with the pthreads version of OpenBLAS, I have added in 0.2.8-4 a patch that disables the annoying warning. -- .''`. Sébastien Villemot : :' : Debian Developer `. `' http://www.dynare.org/sebastien `- GPG Key: 4096R/381A7594
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