Horton

Re: Avoid stack frame setup in performance critical routines using tail calls

David Rowley <dgrowleyml@gmail.com>

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From: David Rowley <dgrowleyml@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>, Michael Paquier <michael.paquier@gmail.com>, Tomas Vondra <tv@fuzzy.cz>
Date: 2021-07-20T04:50:09Z
Lists: pgsql-hackers

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On Tue, 20 Jul 2021 at 08:00, Andres Freund <andres@anarazel.de> wrote:
> I have *not* carefully benchmarked this, but a quick implementation of this
> does seem to increase readonly pgbench tps at a small scale by 2-3% (both

Interesting.

I've not taken the time to study the patch but I was running some
other benchmarks today on a small scale pgbench readonly test and I
took this patch for a spin to see if I could see the same performance
gains.

This is an AMD 3990x machine that seems to get the most throughput
from pgbench with 132 processes

I did: pgbench -T 240 -P 10 -c 132 -j 132 -S -M prepared
--random-seed=12345 postgres

master = dd498998a

Master: 3816959.53 tps
Patched: 3820723.252 tps

I didn't quite get the same 2-3% as you did, but it did come out
faster than on master.

David

Commits

  1. Optimize GenerationAlloc() and SlabAlloc()

  2. Refactor AllocSetAlloc(), separating hot and cold paths

  3. Adjust memory allocation functions to allow sibling calls