[bug#51198] [PATCH] gnu: Add b2sum.

[Leo Famulari]

On Wed, Oct 27, 2021 at 10:44:45AM +0200, Nicolò Balzarotti wrote:
> This blog post [fn:1] on guix-hpc address the "Pre-built binaries
> vs. performance" dilemma.
>
> [fn:1] https://hpc.guix.info/blog/2018/01/pre-built-binaries-vs-performance/

It's helpful, but it doesn't look like we are using that method in Guix
anymore. It was removed in this commit:

https://git.savannah.gnu.org/cgit/guix.git/commit/?id=969adb235ee34decb65255e1ea821ff0e221ed3d

I guess it learned how to do runtime feature detection?

> I guess the easiest way is to provide a variant (b2sum-avx or something
> like that) with avx enabled.  Else, I'd just go with the unoptimized
> version as it happens for many other packages, but let's hear from
> others.

The easiest thing is require local building, since it's an extremely
cheap build. Only 1.5 seconds on my laptop, total (not just the build
phase). With blis, one had to consider the lengthy build time.

Because performance is critical for a tool like this, and because it's
cheap to build, I've attached a patch to require local building. This is
easier for me than creating a set of package variants that will need to
be expanded for each new generation of CPUs :)

0001-gnu-b2sum-Build-on-the-local-machine.patch
Description: Text document