Re: use CLZ instruction in AllocSetFreeIndex()

John Naylor <john.naylor@2ndquadrant.com>

From: John Naylor <john.naylor@2ndquadrant.com>

To: David Fetter <david@fetter.org>

Cc: Tom Lane <tgl@sss.pgh.pa.us>, Alvaro Herrera <alvherre@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2019-12-28T14:50:24Z

Lists: pgsql-hackers

Attachments

v3-0001-Use-the-CLZ-instruction-in-AllocSetFreeIndex.patch (application/octet-stream) patch v3-0001

v2 had an Assert that was only correct while experimenting with
eliding right shift. Fixed in v3.

-- 
John Naylor                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

Micro-optimize AllocSetFreeIndex() by reference to pg_bitutils code.
- 0ce38730ac72 13.0 landed
Speed up AllocSetFreeIndex, which is a significant cost in palloc and pfree,
- ab5b4e2f9ede 9.0.0 cited