Horton

Re: define pg_structiszero(addr, s, r)

David Rowley <dgrowleyml@gmail.com>

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From: David Rowley <dgrowleyml@gmail.com>
To: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Peter Smith <smithpb2250@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, Heikki Linnakangas <hlinnaka@iki.fi>, pgsql-hackers@lists.postgresql.org
Date: 2024-11-01T07:21:50Z
Lists: pgsql-hackers 
On Fri, 1 Nov 2024 at 19:33, Bertrand Drouvot
<bertranddrouvot.pg@gmail.com> wrote:
> Agree, I did a quick test (see [0]) and it looks like it's significantly slower
> using the new inline function.
>
> We could try to write a more elaborate version of pg_memory_is_all_zeros(), but
> as it looks like there is only one use case, then it's probably better to not
> implement (revert) this change here and "just" add a comment as to why pg_memory_is_all_zeros()
> should not be used here, thoughts?

My vote is to just revert this usage of the function. Anything more
elaborate would need to check pointer alignment before using any types
larger than char. The previous code does not need to do that because
the page is going to be at least MAXALIGNed.

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