| From: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
|---|---|
| To: | David Rowley <dgrowleyml(at)gmail(dot)com> |
| Cc: | 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>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andres Freund <andres(at)anarazel(dot)de>, "Shankaran, Akash" <akash(dot)shankaran(at)intel(dot)com>, 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: | 2024-04-06 01:17:04 |
| Message-ID: | 20240406011704.GB167028@nathanxps13 |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Sat, Apr 06, 2024 at 12:08:14PM +1300, David Rowley wrote:
> Won't Valgrind complain about this?
>
> +pg_popcount_avx512(const char *buf, int bytes)
>
> + buf = (const char *) TYPEALIGN_DOWN(sizeof(__m512i), buf);
>
> + val = _mm512_maskz_loadu_epi8(mask, (const __m512i *) buf);
I haven't been able to generate any complaints, at least with some simple
tests. But I see your point. If this did cause such complaints, ISTM we'd
just want to add it to the suppression file. Otherwise, I think we'd have
to go back to the non-maskz approach (which I really wanted to avoid
because of the weird function overhead juggling) or find another way to do
a partial load into an __m512i.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
| From | Date | Subject | |
|---|---|---|---|
| Next Message | David Rowley | 2024-04-06 01:34:17 | Re: Flushing large data immediately in pqcomm |
| Previous Message | John Naylor | 2024-04-06 01:08:19 | Re: fasthash32() returning uint64? |