Horton

RE: Popcount optimization using AVX512

Amonson, Paul D <paul.d.amonson@intel.com>

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From: "Amonson, Paul D" <paul.d.amonson@intel.com>
To: Nathan Bossart <nathandbossart@gmail.com>, David Rowley <dgrowleyml@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Alvaro Herrera <alvherre@alvh.no-ip.org>, "Shankaran, Akash" <akash.shankaran@intel.com>, Noah Misch <noah@leadboat.com>, Tom Lane <tgl@sss.pgh.pa.us>, "Matthias van de Meent" <boekewurm+postgres@gmail.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Date: 2024-03-18T16:07:40Z
Lists: pgsql-hackers

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  1. Fix __attribute__((target(...))) usage.

  2. Use __attribute__((target(...))) for AVX-512 support.

  3. Fix code for probing availability of AVX-512.

  4. Optimize visibilitymap_count() with AVX-512 instructions.

  5. Optimize pg_popcount() with AVX-512 instructions.

  6. Inline pg_popcount() for small buffers.

  7. Avoid function call overhead of pg_popcount() in syslogger.c.

  8. Refactor code for setting pg_popcount* function pointers.

  9. Inline pg_popcount{32,64} into pg_popcount().

  10. Remove MSVC scripts

  11. Use ARMv8 CRC instructions where available.

  12. Use Intel SSE 4.2 CRC instructions where available.

Won't I still need the runtime checks? If I compile with a compiler supporting the HW "feature" but run on HW without that feature,  I will want to avoid faults due to illegal operations. Won't that also affect performance?

Paul

> -----Original Message-----
> From: Nathan Bossart <nathandbossart@gmail.com>
> Sent: Monday, March 18, 2024 8:29 AM
> To: David Rowley <dgrowleyml@gmail.com>
> Cc: Amonson, Paul D <paul.d.amonson@intel.com>; Andres Freund
> <andres@anarazel.de>; Alvaro Herrera <alvherre@alvh.no-ip.org>; Shankaran,
> Akash <akash.shankaran@intel.com>; Noah Misch <noah@leadboat.com>;
> Tom Lane <tgl@sss.pgh.pa.us>; Matthias van de Meent
> <boekewurm+postgres@gmail.com>; pgsql-hackers@lists.postgresql.org
> Subject: Re: Popcount optimization using AVX512
> 
> On Mon, Mar 18, 2024 at 09:56:32AM +1300, David Rowley wrote:
> > Maybe it's worth exploring something along the lines of the attached
> > before doing the AVX512 stuff.  It seems like a pretty good speed-up
> > and will apply for CPUs without AVX512 support.
> 
> +1
> 
> --
> Nathan Bossart
> Amazon Web Services: https://aws.amazon.com