Re: [PATCH] cksum: Use AVX2 and AVX512 for speedup

[Sam Russell]

Nice find protecting the flag checks, thanks for your help.

Thanks also to Jeff for giving me access to test on a few different
machines with various levels of avx2/avx512 support

On Tue, Nov 26, 2024, 17:19 Pádraig Brady <P@draigbrady.com> wrote:

> On 26/11/2024 12:19, Sam Russell wrote:
> >  > Now I think what you are saying is there was no SIGILL with the
> adjusted cksum,
> > and that issue was only with the less protected benchmarking code.
> >
> > Correct, the benchmarking code has zero protections, and the servers I
> got SIGILL they were not setting the VPCLMULQDQ flag so cksum will catch
> this and fall back
>
> Thanks for the confirmation.
>
> I've tweaked NEWS a bit and also adjusted the avx2_supported() and
> avx512_supported()
> functions to avoid a build failure which I think would happen on x86 with
> gcc 8 for example,
> by protecting the builtin_cpu_supports() calls with USE_AVX2_CRC32 and
> USE_AVX512_CRC32.
> I'll push in a couple of hours.
>
> thanks!
> Pádraig
>
>
>