| From: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
|---|---|
| To: | "Amonson, Paul D" <paul(dot)d(dot)amonson(at)intel(dot)com> |
| Cc: | David Rowley <dgrowleyml(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, "Shankaran, Akash" <akash(dot)shankaran(at)intel(dot)com>, Noah Misch <noah(at)leadboat(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Popcount optimization using AVX512 |
| Date: | 2024-03-18 17:53:50 |
| Message-ID: | 20240318175350.GA413342@nathanxps13 |
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| Lists: | pgsql-hackers |
On Mon, Mar 18, 2024 at 12:30:04PM -0500, Nathan Bossart wrote:
> Here is a more fleshed-out version of what I believe David is proposing.
> On my machine, the gains aren't quite as impressive (~8.8s to ~5.2s for the
> test_popcount benchmark). I assume this is because this patch turns
> pg_popcount() into a function pointer, which is what the AVX512 patches do,
> too. I left out the 32-bit section from pg_popcount_fast(), but I'll admit
> that I'm not yet 100% sure that we can assume we're on a 64-bit system
> there.
>
> IMHO this work is arguably a prerequisite for the AVX512 work, as turning
> pg_popcount() into a function pointer will likely regress performance for
> folks on systems without AVX512 otherwise.
Apologies for the noise. I noticed that we could (and probably should)
inline the pg_popcount32/64 calls in the "slow" version, too.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
| Attachment | Content-Type | Size |
|---|---|---|
| 0001-inline-function-calls-in-pg_popcount-when-possible.patch | text/x-diff | 7.1 KB |
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