[PATCH v3] Reversing calculation of __x86_shared_non_temporal_threshold

[Carlos O'Donell]

On 10/1/20 12:04 PM, Patrick McGehearty wrote:
> Having said that, a preliminary test could be developed by making
> (and documenting) as many simplifying assumptions as necessary
> to start. Then address each simplifying assumption in turn
> according to their difficulty. I would find it to be an interesting project,
> but I won't volunteer for it at the current time due to my existing
> work backlog. I'd be happy to provide review & morale support to
> someone else's efforts in this direction.

Patrick,

Thank you for those notes. I've bookmarked this to refer back to them as
we continue to develop more microbenchmarks.

I think we *can* write more generic microbenchmarks that can range across
the implementation specific details of the hardware to verify where the
cliff lies for performance. Such paraterization of the problem space
seems doable. I think we need some "pin process to cpu" framework and
probably some "what does this topology look like" framework, so we'll
need access to some of the numa topology libraries on the benchmark to
suss out at runtime how we layout and pin things and provide overrides
e.g. spit out json of our understanding or take json as input for what
the developer tells you to do for layout.

I'm OK with `make bench` taking a long time because it is usually
run under direct supervision by someone on a stable, clean, unloaded
system. I am not naive enough to think we're ever going to reliably
automate any of this even with a benchset that is smaller.

Thanks again.

-- 
Cheers,
Carlos.