Re: [eigen] Architecture specific performance optimizations

[Rhys Ulerich <rhys.ulerich@xxxxxxxxx>]

> I think as a first step, we should have some kind of survey on what
> platforms Eigen currently is used, who requires to have top-performance (I
> would assume this correlates with people having up-to-date hardware).

Everyone will claim they need top performance.

Is there an automatic performance reporting capability within CDash,
or similar?  Caring enough about performance to set up CI hardware
that automatically submits to a central tracking system (or enough to
buy such hardware for a core developer) is a great
this-platform-deserves-attention threshold.  Plus, it's the only way
to understand narrow the changes triggering regressions without access
to the entire fleet of chips.

The approach works well already from a compiler-support perspective.
Folks who care sufficiently, if they see their compiler vendor/version
isn't covered, personally submit to CDash.

(None of this is meant to be a slap to people who don't run
correctness CI or who wouldn't run performance CI.  I personally would
likely skip running performance CI.  Everyone has finite time and
resources.)

- Rhys