Horton

Re: define pg_structiszero(addr, s, r)

Ranier Vilela <ranier.vf@gmail.com>

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From: Ranier Vilela <ranier.vf@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, Bertrand Drouvot <bertranddrouvot.pg@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, pgsql-hackers@lists.postgresql.org
Date: 2024-10-28T16:29:08Z
Lists: pgsql-hackers 
Em seg., 28 de out. de 2024 às 12:08, Tom Lane <tgl@sss.pgh.pa.us> escreveu:

> Ranier Vilela <ranier.vf@gmail.com> writes:
> > It seems to me that [reversing the loop direction] is more optimized.
>
> That's far from clear: you're ignoring the possibility that memory
> access logic is better optimized for forward scanning than reverse
> scanning.  I'd stick with the forward scan without some extremely
> detailed testing.
>
I don't disagree.
After posting, I was wondering if the first possible is not zero, it should
probably be at the beginning and not at the end.

best regards,
Ranier Vilela

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