| From: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
|---|---|
| To: | "Devulapalli, Raghuveer" <raghuveer(dot)devulapalli(at)intel(dot)com> |
| Cc: | "Shankaran, Akash" <akash(dot)shankaran(at)intel(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, David Rowley <dgrowleyml(at)gmail(dot)com>, Ants Aasma <ants(dot)aasma(at)cybertec(dot)at>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, "Amonson, Paul D" <paul(dot)d(dot)amonson(at)intel(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Noah Misch <noah(at)leadboat(dot)com>, 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: | 2024-04-18 22:13:58 |
| Message-ID: | 20240418221358.GA3927188@nathanxps13 |
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| Lists: | pgsql-hackers |
On Thu, Apr 18, 2024 at 10:11:08PM +0000, Devulapalli, Raghuveer wrote:
>> On that note, is it necessary to also check for avx512f? At the moment,
>> we are assuming that's supported if the other AVX-512 instructions are
>> available.
>
> No, it's not needed. There are no CPU's with avx512bw/avx512popcnt
> without avx512f. Unfortunately though, avx512popcnt does not mean
> avx512bw (I think the deprecated Xeon Phi processors falls in this
> category) which is why we need both.
Makes sense, thanks. I'm planning to commit this fix sometime early next
week.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
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