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Date: Thu, 18 Jun 2026 11:25:00 +0200
From: Christoph Hellwig <hch@lst.de>
To: David Laight <david.laight.linux@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>, Eric Biggers <ebiggers@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
	x86@kernel.org, linux-raid@vger.kernel.org
Subject: Re: [PATCH v3] lib/raid/xor: x86: Add AVX-512 optimized xor_gen()
Message-ID: <20260618092500.GC17530@lst.de>
References: <20260615190338.26581-1-ebiggers@kernel.org> <20260617055653.GB19218@lst.de> <20260617110516.0a70950e@pumpkin>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Wed, Jun 17, 2026 at 11:05:16AM +0100, David Laight wrote:
> > FYI, one or 2 sources are basically useless as they RAID5 configs
> > that have no benefits over simple mirroring and thus the numbers
> > aren't too interesting.
> 
> With three disks you xor two buffers (src_count == 1) to get the parity
> to write to the third - so that is a valid RAID5 config.

Sure.  It did not say it is invalid, it just isn't very useful.