| From: | David Rowley <dgrowleyml(at)gmail(dot)com> |
|---|---|
| To: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
| Cc: | Ranier Vilela <ranier(dot)vf(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Optmize bitmapword macros calc (src/backend/nodes/bitmapset.c) |
| Date: | 2024-01-29 22:23:57 |
| Message-ID: | CAApHDvqJA9FmiKS5zoRceGFKUY8Y8-pBXVoGVJKyvMPLy=k6SQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, 30 Jan 2024 at 08:32, Nathan Bossart <nathandbossart(at)gmail(dot)com> wrote:
> I'm currently +0.1 for this change. I don't see any huge problem with
> trimming a few instructions, but I'm dubious there's any measurable impact.
> However, a cycle saved is a cycle earned...
FWIW, In [1] and subsequent replies, there are several examples of
benchmarks where various bitmapset functions are sitting high in the
profiles. So I wouldn't be too surprised if such a small change to the
WORDNUM and BITNUM macros made a noticeable difference.
A benchmark speaks a thousand words, however.
David
[1] https://postgr.es/m/CAApHDvq9eq0W_aFUGrb6ba28ieuQN4zM5Uwqxy7+LMZjJc+VGg@mail.gmail.com
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