From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (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 93B5140149E; Mon, 29 Jun 2026 12:47:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782737257; cv=none; b=p/5238a4eh4VbKGdcmV5xCK6u4pMsP4cJ9/kcm3NUxkoTBOQISJ94YWxiv+/cFRe5mhaFW89dywTifQ6ezuEiG4lsCumy9Ucy5NjxxwnqaJGtFep8+f/O3H8nfdUKC1ILzcq92U0vr8sZYJG+AV9IKafpQF5dAkPB4xjmlfLuZo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782737257; c=relaxed/simple; bh=z/WphS08I3Q3YI1k39FHOZlyjeIMdtgSIvsLXR1+OYs=; h=Date:From:To:CC:Subject:In-Reply-To:References:Message-ID: MIME-Version:Content-Type; b=BHyeU7BlOJ+U4mjacCa7QcYdXGSNKBKeitBlhU/iBEowdXMiCBzQDDx9lGd5Oi4nLo6h2Lgp4fnUCVudiE5tblMyilfogK5jNh2iE+86q6cxcXnrDJJRlQfK4V+vjtssV/Kp1s1bug5iGInXhzpy1X+389p2cMc7KZvx3wrkgiY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=ItDa3yOy; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="ItDa3yOy" Received: from ehlo.thunderbird.net (c-76-133-66-138.hsd1.ca.comcast.net [76.133.66.138]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 65TCYlVH219229 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Mon, 29 Jun 2026 05:34:48 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 65TCYlVH219229 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2026062701; t=1782736492; bh=F5eNBCeca9FFTuFbHhVBFOemJYWYzDmHgzejZkXlIwM=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=ItDa3yOyOnzgUJtBSZCdhS4zlYRD1XzlbHnWBCrsgDuyOKDQnLXWfugxh1RYrcnHj Wo6d2ASe4aa2kENlvakDGwv3s+KtWwghI1YzuSK4mfraTOB1p7+BurPnKzbMpbQKQL FArnwwcKd8vhlMO88QNlKM8z1OAEuHhiE7bWCyq/7xJ09JZm9//17j5avtQhx3ZQCW 62VMIArJVSZ3KSFw9+v6qyIZPgiOE1KxeelvfNkr5eljLOhZuntNE2qq7OnkyMcON6 lCC018LGMBA4PoGUZ03daik0PWEEF4Ej3Y7mFmcxCoVSXT9w4uUsvXWEvA5Jy73wT+ n9LoSC8sobApw== Date: Mon, 29 Jun 2026 05:34:41 -0700 From: "H. Peter Anvin" To: Christoph Hellwig CC: Andrew Morton , Catalin Marinas , Will Deacon , Ard Biesheuvel , 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 , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Herbert Xu , Dan Williams , Chris Mason , David Sterba , Arnd Bergmann , Song Liu , Yu Kuai , Li Nan , 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, linux-crypto@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-arch@vger.kernel.org, linux-raid@vger.kernel.org Subject: Re: cleanup the RAID6 P/Q library v3 User-Agent: K-9 Mail for Android In-Reply-To: <20260629122152.GA21344@lst.de> References: <20260518051804.462141-1-hch@lst.de> <20260518141205.c100f76eec5f58e78bbbf7af@linux-foundation.org> <20260519082432.GA14956@lst.de> <7d8efc7c-65e3-49f8-9381-910de7affef2@zytor.com> <20260629122152.GA21344@lst.de> Message-ID: <8684FEC2-AD56-4BDA-874F-1D3D7170F880@zytor.com> Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On June 29, 2026 5:21:52 AM PDT, Christoph Hellwig wrote: >On Fri, Jun 26, 2026 at 05:52:18PM -0700, H=2E Peter Anvin wrote: >> On 2026-05-19 01:24, Christoph Hellwig wrote: >> >=20 >> > raid6: rework registration of optimized algorithms >> >=20 >> > - avx2 instead of avx512 is probably the right thing for no >> > benchmarking, but if it was intentional (it wasn't), that should >> > be document=2E So I'll just switch back to the previous version t= o >> > keep the state of the art >>=20 >> It is unlikely to be the right thing *going forward*, though=2E >>=20 >> The very unfortunate performance inversion is likely model-specific=2E = It is one >> of those things where you largely would have to have a list of quirks := ( > >Note that the default is still to benchmark the implementations=2E >This is just about the case where the user explicitly disabled that >benchmark-based selection=2E > The real issue though is that the benchmarking isn't really helpful, eithe= r=2E=20 It has to do with power across the whole chip, so it perversely enough dep= ends on what *else* is going on=2E=2E=2E