From: Nathan Bossart <nathan@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Optimize visibilitymap_count() with AVX-512 instructions.
Date: Sun, 07 Apr 2024 04:00:52 +0000
Message-ID: <E1rtJi8-000ucP-Cg@gemulon.postgresql.org> (raw)
Optimize visibilitymap_count() with AVX-512 instructions.
Commit 792752af4e added infrastructure for using AVX-512 intrinsic
functions, and this commit uses that infrastructure to optimize
visibilitymap_count(). Specificially, a new pg_popcount_masked()
function is introduced that applies a bitmask to every byte in the
buffer prior to calculating the population count, which is used to
filter out the all-visible or all-frozen bits as needed. Platforms
without AVX-512 support should also see a nice speedup due to the
reduced number of calls to a function pointer.
Co-authored-by: Ants Aasma
Discussion: https://postgr.es/m/BL1PR11MB5304097DF7EA81D04C33F3D1DCA6A%40BL1PR11MB5304.namprd11.prod.outlook.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/41c51f0c68b21b4603bd2a9c3d3ad017fdd22627
Modified Files
--------------
src/backend/access/heap/visibilitymap.c | 25 ++-----
src/include/port/pg_bitutils.h | 34 +++++++++
src/port/pg_bitutils.c | 126 ++++++++++++++++++++++++++++++++
src/port/pg_popcount_avx512.c | 60 +++++++++++++++
4 files changed, 225 insertions(+), 20 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: nathan@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Optimize visibilitymap_count() with AVX-512 instructions.
In-Reply-To: <E1rtJi8-000ucP-Cg@gemulon.postgresql.org>
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