Re:Zen4's AVX512 Teardown
by janwas on Tuesday September 27, 2022 @01:11AM
(#32991748)
> The gains AVX512 brings over AVX2 are, for most people w/ specialty libs excluded
The last two things I worked on, image compression and quicksort, see 1.4-1.6x end to end speedups from AVX-512 vs AVX2. Is that sufficiently motivating? Especially because the only thing we had to do was ensure that CI machines are AVX-512 capable so that those test codepaths also run.
The "terrible CPU support" is a fact of life, not just in x86 (AES is 'optional' in SVE2, sigh), and so we deal with it via runtime dispatch - using what the CPU supports.
The last two things I worked on, image compression and quicksort, see 1.4-1.6x end to end speedups from AVX-512 vs AVX2. Is that sufficiently motivating? Especially because the only thing we had to do was ensure that CI machines are AVX-512 capable so that those test codepaths also run.
The "terrible CPU support" is a fact of life, not just in x86 (AES is 'optional' in SVE2, sigh), and so we deal with it via runtime dispatch - using what the CPU supports.