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Date: Fri, 26 Jun 2026 07:47:31 +0200
From: Christoph Hellwig <hch@lst.de>
To: Eric Biggers <ebiggers@kernel.org>
Cc: x86@kernel.org, linux-um@lists.infradead.org,
	linux-raid@vger.kernel.org, linux-crypto@vger.kernel.org,
	linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	David Laight <david.laight.linux@gmail.com>
Subject: Re: [PATCH 8/8] lib/raid/xor: x86: Add AVX-512 optimized xor_gen()
Message-ID: <20260626054731.GC9629@lst.de>
References: <20260626043731.319287-1-ebiggers@kernel.org> <20260626043731.319287-9-ebiggers@kernel.org>
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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).