Re: OpenBLAS and performance

[Pjotr Prins]

On Fri, Dec 22, 2017 at 04:10:39PM +0100, Ludovic Courtès wrote:
> Static binding has a cost, as you write, but it gives us control over
> the environment, and the ability to capture and replicate the software
> environment.  As a user, that’s something I value a lot.

> I’d also argue that this is something computational scientists should
> value: first because results they publish should not depend on the phase
> of the moon, second because they should be able to provide peers with a
> self-contained recipe to reproduce them.

As a scientist I value that *more* than a lot. There is a tension
between 'just getting things done' and making things reproducible. If
we can do the latter, we should.  Also as a programmer I value
reproducibility a lot. I want people who report bugs to use the exact
same setup. Especially when they are running on machines I can not
access (quite common in sequencing centers). If someone sends me a
core dump, stack trace or even an asserting in a shared lib it is
incredibly useful the full stack is the same.

I am wary of flexible resolution of optimized libraries and kernels.
Look at what atlas tried to do and what a mess it became. I strongly
believe we need explicit statements about what we are running. It does
imply Guix will have to provide all options, directly or through
channels.

I also work on HPC and if I know where I am running I know *what* to
target. It is a deterministic recipe. 

Pj.