From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 479764B8DC0; Tue, 3 Mar 2026 16:11:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.11.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772554315; cv=none; b=BdkCCFGpKvxK+oaqXxam0xVm2thnZEb2GCe+hIRVVWDCV7PeZyIGUKjtz6+rvPmqBE+QAaQWLZ0xjRzsY1bbpgr7VkyzCXvTqYMrmh3VBoW66z4GP1JpZKZf3PWHkJnc95jxHX1JBwaUeIuRxkRDtbI3+eJkqQiTrE1Urr5m1Sw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772554315; c=relaxed/simple; bh=qXfMFx1V+SjVZ1JKY59h8uVCQyv/ezN1YeeaK8ler8s=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=L8eCwVgG3/P02nIJ0AKUf+KgRyJmk6K+Lc7ahVIFtDojUCjQuOPP2XFCZ3buLQKWQqgDmcLpG/y1++mV42FTRlsRVmEujWN3FBMWt5PIIVUB6oZ9Sy49wXvvdO8q8Z4nlQpRATKwFLV7nvOMxc8dIP/ztNh8EUL3H4uW+zDenY8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de; spf=pass smtp.mailfrom=lst.de; arc=none smtp.client-ip=213.95.11.211 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lst.de Received: by verein.lst.de (Postfix, from userid 2407) id E4C7E68BEB; Tue, 3 Mar 2026 17:11:45 +0100 (CET) Date: Tue, 3 Mar 2026 17:11:45 +0100 From: Christoph Hellwig To: Eric Biggers Cc: Christoph Hellwig , Andrew Morton , Richard Henderson , Matt Turner , Magnus Lindholm , Russell King , Catalin Marinas , Will Deacon , Huacai Chen , WANG Xuerui , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , "David S. Miller" , Andreas Larsson , Richard Weinberger , Anton Ivanov , Johannes Berg , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Herbert Xu , Dan Williams , Chris Mason , David Sterba , Arnd Bergmann , Song Liu , Yu Kuai , Li Nan , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-crypto@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-arch@vger.kernel.org, linux-raid@vger.kernel.org Subject: Re: cleanup the RAID5 XOR library Message-ID: <20260303161145.GK7021@lst.de> References: <20260226151106.144735-1-hch@lst.de> <20260228073553.GL65277@quark> Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260228073553.GL65277@quark> User-Agent: Mutt/1.5.17 (2007-11-01) On Fri, Feb 27, 2026 at 11:35:53PM -0800, Eric Biggers wrote: > > https://git.infradead.org/?p=users/hch/misc.git;a=shortlog;h=refs/heads/xor-improvements > > Overall this looks great. xor_gen() really needs a KUnit test, though. > Without that, how was this tested? fio data integrity testing on degraded raid. But yes, a unit test would be nice. > Later we should remove some of the obsolete implementations, such as the > alpha or x86 MMX ones. Those platforms have no optimized code in > lib/crc/ or lib/crypto/, and I doubt anyone cares. I'd rather leave that to the architecture maintainers, but overall I ahree. > Also, I notice that no one has optimized this for the latest x86_64 CPUs > by using the vpternlogd instruction to do 3-input XORs. That would be > another good future project. Yes, as would rewriting the routines to deal with more than 4 + 1 stripes as that is a really narrow raid these days.