RE: Popcount optimization using AVX512

> -----Original Message-----
> From: Nathan Bossart <nathandbossart(at)gmail(dot)com>
> Sent: Monday, March 11, 2024 6:35 PM
> To: Amonson, Paul D <paul(dot)d(dot)amonson(at)intel(dot)com>

> Thanks. There's no need to wait to post the AVX portion. I recommend using
> "git format-patch" to construct the patch set for the lists.

After exploring git format-patch command I think I understand what you need. Attached.

> > What exactly do you suggest here? I am happy to always call either
> > pg_popcount32() or pg_popcount64() with the understanding that it may
> > not be optimal, but I do need to know which to use.
>
> I'm recommending that we don't change any of the code in the pg_popcount()
> function (which is renamed to pg_popcount_slow() in your v6 patch). If
> pointers are 8 or more bytes, we'll try to process the buffer in 64-bit chunks.
> Else, we'll try to process it in 32-bit chunks. Any remaining bytes will be
> processed one-by-one.

Ok, we are on the same page now. :) It is already fixed that way in the refactor patch #1.

As for new performance numbers: I just ran a full suite like I did earlier in the process. My latest results an equivalent to a pgbench scale factor 10 DB with the target column having varying column widths and appropriate random data are 1.2% improvement with a 2.2% Margin of Error at a 98% confidence level. Still seeing improvement and no regressions.

As stated in the previous separate chain I updated the code removing the extra "extern" keywords.

Thanks,
Paul