On Wed, 1 Jul 2020 at 19:03, Jerry James <loganje...@gmail.com> wrote: > > On Wed, Jul 1, 2020 at 10:26 AM Iñaki Ucar <iu...@fedoraproject.org> wrote: > > BTW, I would also like to discuss here, as part of this proposal, > > which backend should be the system-wide default. I believe we all > > would agree that OpenBLAS nowadays is the best choice. But then, the > > serial or the openmp version? > > First, I want to make sure I understand the current openblas > packaging. Is this correct? > > openblas-openmp: use if the application uses OpenMP > openblas-serial: use if the application is multithreaded > openblas-threads: use if the application is single-threaded > > I've always found the naming of the openblas packages to be confusing, > so that may not be right. Somebody set me straight if so.
The naming means (the same for BLIS): -serial: runs single-threaded. -openmp: some parts use OpenMP. -threads: runs multi-threaded. So it's a property of the OpenBLAS build, not a property of the application. In fact, the serial version is not thread-safe unless you activate a particular option at build time. We found that issue recently and fixed it, and BTW the workaround was to switch to openblas-openmp. Potentially, you could run every version regardless of the application, but some combinations are clearly a no-go, like a threaded OpenBLAS in a threaded application. > The question of the default is a hard one. What happens if a > multithreaded application that does not use OpenMP is linked with the > OpenMP build of OpenBLAS? That combination is fine AFAIK. But I don't know whether the serial version would perform better in that situation or not at all. I'll bother the FlexiBLAS maintainer about this. :) They use FlexiBLAS as a research tool in high-performance computing, so maybe he knows better about all these possible combinations. -- Iñaki Úcar _______________________________________________ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org
