On Fri, 17 Jul 2020 at 10:34, Dave Love loveshack@fedoraproject.org wrote:
[I found I hadn't sent this earlier, as I should have.]
https://fedoraproject.org/wiki/Changes/FlexiBLAS_as_BLAS/LAPACK_manager
== Summary == BLAS/LAPACK packages will be compiled against the FlexiBLAS wrapper library, which will set OpenBLAS as system-wide default backend, and at the same time will provide a proper switching mechanism that currently Fedora lacks.
I oppose this (in favour of a different approach) from experience in research computing system management, general support, and implementation. It doesn't solve any problem I (have) had, as far as I can tell, and looks as if it produces more. The licence seems to me to rule it out a priori.
The authors are going to add an exception, so the license won't be a problem. What problems do you think it produces?
The proposal doesn't justify things, including its dismissal of the simple, clean alternative in similar to Debian's, with which I have some
I don't justify that because Debian's alternative has been repeatedly dismissed as an option for Fedora for a simple reason: one could end up with libblas pointing to one implementation and liblapack pointing to another. This problem, that Debian has, is solved with this library.
There will be hoops to jump through to get packages to configure when they don't know about the library.
I don't think so, but if there are serious issues, rolling back the change is pretty straightforward.
If I want to use a library that's not included, I'm in the same position.
No, you are not. You just need to point to that library using the FLEXIBLAS environment variable.
It's not clear to me a priori what happens if you try to use just BLIS even, given that OpenBLAS' LAPACK implementation isn't the vanilla one, and depends on OpenBLAS as far as I know.
I don't understand this. You can switch to BLIS easily. The default one doesn't matter.
The choice of OpenBLAS isn't justified. It's not even obvious that you want the same implementation for serial and multi-threaded as OpenBLAS seems to have had continual problems with threading which BLIS hasn't as far as I know. I expect OpenBLAS is the best serial option on average, at least, but that needs data for different architectures.
This is about having a sane default one. That's it. You can switch then to whatever implementation you want.
I realize no-one is going to be running Fedora on HPC systems, where this really matters, but presumably it filters down to RHEL, which is looking less and less like a good HPC platform to me.
Actually, FlexiBLAS is developed by researchers in HPC.