Horton

Re: define pg_structiszero(addr, s, r)

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: David Rowley <dgrowleyml@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, Ranier Vilela <ranier.vf@gmail.com>, Peter Smith <smithpb2250@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, pgsql-hackers@lists.postgresql.org
Date: 2024-11-07T08:41:52Z
Lists: pgsql-hackers 
Hi,

On Thu, Nov 07, 2024 at 09:45:44AM +0900, Michael Paquier wrote:
> On Thu, Nov 07, 2024 at 08:05:10AM +1300, David Rowley wrote:
> > That might be quite good for small lengths or for use cases where the
> > memory is always or almost always zero. The problem is there's no
> > early exit when you find the first non-zero which means, for larger
> > lengths, reading much more memory. That'll both take longer and
> > possibly evict cache lines which might be useful to have in the near
> > future.
> 
> Didn't know this one either, thanks for the explanation.

+1, thanks!

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

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