RE: Popcount optimization using AVX512

> -----Original Message-----
> From: Amonson, Paul D <paul(dot)d(dot)amonson(at)intel(dot)com>
> Sent: Friday, March 15, 2024 8:31 AM
> To: Nathan Bossart <nathandbossart(at)gmail(dot)com>
...
> When I tested the code outside postgres in a micro benchmark I got 200-
> 300% improvements. Your results are interesting, as it implies more than
> 300% improvement. Let me do some research on the benchmark you
> referenced. However, in all cases it seems that there is no regression so should
> we move forward on merging while I run some more local tests?

When running quick test with small buffers (1 to 32K) I see up to about a 740% improvement. This was using my stand-alone micro benchmark outside of PG. My original 200-300% numbers were averaged including sizes up to 512MB which seems to not run as well on large buffers. I will try the referenced micro benchmark on Monday. None of my benchmark testing used the command line "time" command. For Postgres is set "\timing" before the run and for the stand-alone benchmark is took timestamps in the code. In all cases I used -O2 for optimization.

Thanks,
Paul