Horton

Re: define pg_structiszero(addr, s, r)

David Rowley <dgrowleyml@gmail.com>

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From: David Rowley <dgrowleyml@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>, Ranier Vilela <ranier.vf@gmail.com>, Peter Smith <smithpb2250@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, Heikki Linnakangas <hlinnaka@iki.fi>, pgsql-hackers@lists.postgresql.org
Date: 2024-11-06T02:53:48Z
Lists: pgsql-hackers 
On Wed, 6 Nov 2024 at 13:52, Michael Paquier <michael@paquier.xyz> wrote:
>
> On Wed, Nov 06, 2024 at 01:38:50PM +1300, David Rowley wrote:
> > We could just write it that way and leave it up to the compiler to
> > decide whether to use SIMD or not. Going by [1], gcc with -O2 uses
> > SIMD instructions from 14.1 and clang with -O2 does it from version
> > 8.0.0. gcc 14.1 was release in May 2024, so still quite new. It'll be
> > quite a bit older once PG18 is out.  Using the bitwise-OR method, more
> > and more people will benefit as gcc14.1 and beyond becomes more
> > mainstream.
> >
> > Clang 8.0.0 is from March 2019, so quite old already.
>
> Okay, WFM to keep things the way they are in the patch.

I'm not sure if I'm clear on what works for you.  The latest patch I
saw did 1 size_t per iteration. Are you saying we should do just
size_t per loop? or we should form the code in a way that allows the
compiler to use SIMD instructions?

David

Commits

  1. Use pg_memory_is_all_zeros() in PageIsVerifiedExtended()

  2. Optimize pg_memory_is_all_zeros() in memutils.h

  3. Remove use of pg_memory_is_all_zeros() in bufpage.c

  4. Add pg_memory_is_all_zeros() in memutils.h