Re: define pg_structiszero(addr, s, r)
Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: David Rowley <dgrowleyml@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: 2024-11-06T11:40:06Z
Lists: pgsql-hackers
Hi,
On Wed, Nov 06, 2024 at 01:44:58PM +0900, Michael Paquier wrote:
> Should the last loop check only 1 byte at a time or should this stuff
> include one more step before the last one you wrote to do a couple of
> checks with size_t? That may matter for areas small enough (len <
> sizeof(size_t) * 8) causing the second step to not be taken, but large
> enough (len > sizeof(size_t)) to apply a couple of size_t checks per
> loop.
Do you mean add:
"
for (; p < aligned_end; p += sizeof(size_t))
{
if (*(size_t *)p != 0)
return false;
}
"
just before the last loop?
If so, I did a few tests and did not see any major improvements. So, I thought
it's simpler to not add more code in this inline function in v7 shared up-thread.
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
Commits
-
Use pg_memory_is_all_zeros() in PageIsVerifiedExtended()
- 03a42c9652f8 18.0 landed
-
Optimize pg_memory_is_all_zeros() in memutils.h
- 5be1dabd2ae0 18.0 landed
-
Remove use of pg_memory_is_all_zeros() in bufpage.c
- e819bbb7c82a 18.0 landed
-
Add pg_memory_is_all_zeros() in memutils.h
- 07e9e28b56db 18.0 landed