Re: [PATCH 8/8] lib/raid/xor: x86: Add AVX-512 optimized xor_gen()
From: Christoph Hellwig
Date: Fri Jun 26 2026 - 01:48:46 EST
On Thu, Jun 25, 2026 at 09:37:31PM -0700, Eric Biggers wrote:
> + if (IS_ENABLED(CONFIG_X86_64) && boot_cpu_has(X86_FEATURE_AVX512F) &&
> + !boot_cpu_has(X86_FEATURE_PREFER_YMM)) {
> + /* AVX-512 will be the best; no need to try others. */
> + /* !PREFER_YMM excludes CPUs with overly-eager downclocking. */
Can you turn this into a single block comment using full sentences?
Right now the two separate comments almost feel contradictory even
if I get what you mean. While you're at it also through in a blurb
why we dont bother with AVX-512 (number of register, no one in the right
mind would bother running high performance code on modern cpus in 32-bit
mode).