Horton

Re: Popcount optimization using AVX512

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: "Amonson, Paul D" <paul.d.amonson@intel.com>
Cc: Nathan Bossart <nathandbossart@gmail.com>, Andres Freund <andres@anarazel.de>, "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: 2024-03-07T17:53:12Z
Lists: pgsql-hackers

Commits

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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.

On 2024-Mar-04, Amonson, Paul D wrote:

> > -#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
> > +#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31)
> > +<< 31))
> >
> > IME this means that the autoconf you are using has been patched.  A
> > quick search on the mailing lists seems to indicate that it might be
> > specific to Debian [1].
>  
> I am not sure what the ask is here?  I made changes to the
> configure.ac and ran autoconf2.69 to get builds to succeed. Do you
> have a separate feedback here? 

So what happens here is that autoconf-2.69 as shipped by Debian contains
some patches on top of the one released by GNU.  We use the latter, so
if you run Debian's, then the generated configure script will contain
the differences coming from Debian's version.

Really, I don't think this is very important as a review point, because
if the configure.ac file is changed in the patch, it's best for the
committer to run autoconf on their own, using a pristine GNU autoconf;
the configure file in the submitted patch is not relevant, only
configure.ac matters.

What committers do (or should do) is keep an install of autoconf-2.69
straight from GNU.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/