Re: Popcount optimization using AVX512

Nathan Bossart <nathandbossart@gmail.com>

From: Nathan Bossart <nathandbossart@gmail.com>

To: Tom Lane <tgl@sss.pgh.pa.us>

Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Ants Aasma <ants.aasma@cybertec.at>, "Amonson, Paul D" <paul.d.amonson@intel.com>, David Rowley <dgrowleyml@gmail.com>, Andres Freund <andres@anarazel.de>, "Shankaran, Akash" <akash.shankaran@intel.com>, Noah Misch <noah@leadboat.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>

Date: 2024-04-02T22:20:20Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Fix __attribute__((target(...))) usage.
- 41b98ddb77bf 18.0 landed
Use __attribute__((target(...))) for AVX-512 support.
- f78667bd910e 18.0 landed
Fix code for probing availability of AVX-512.
- 598e0114a3b1 17.0 landed
Optimize visibilitymap_count() with AVX-512 instructions.
- 41c51f0c68b2 17.0 landed
Optimize pg_popcount() with AVX-512 instructions.
- 792752af4eb5 17.0 landed
Inline pg_popcount() for small buffers.
- deb1486c7d36 17.0 landed
Avoid function call overhead of pg_popcount() in syslogger.c.
- 4133c1f45c54 17.0 landed
Refactor code for setting pg_popcount* function pointers.
- 6687430c98f3 17.0 landed
Inline pg_popcount{32,64} into pg_popcount().
- cc4826dd5e52 17.0 landed
Remove MSVC scripts
- 1301c80b2167 17.0 cited
Use ARMv8 CRC instructions where available.
- f044d71e331d 11.0 cited
Use Intel SSE 4.2 CRC instructions where available.
- 3dc2d62d0486 9.5.0 cited

Attachments

v22-0001-inline-pg_popcount-for-small-numbers-of-bytes.patch (text/x-diff)

On Tue, Apr 02, 2024 at 05:01:32PM -0500, Nathan Bossart wrote:
> In v21, 0001 is just the above inlining idea, which seems worth doing
> independent of $SUBJECT.  0002 and 0003 are the AVX-512 patches, which I've
> modified similarly to 0001, i.e., I've inlined the "fast" version in the
> function pointer to avoid the function call overhead when there are fewer
> than 64 bytes.  All of this overhead juggling should result in choosing the
> optimal popcount implementation depending on how many bytes there are to
> process, roughly speaking.

Sorry for the noise.  I noticed a couple of silly mistakes immediately
after sending v21.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com