[PATCH 8/8] lib/raid/xor: x86: Add AVX-512 optimized xor_gen()

Christoph Hellwig hch at lst.de
Thu Jun 25 22:47:31 PDT 2026


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).




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