From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B712DC43458 for ; Mon, 29 Jun 2026 12:22:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=dircqAEtLKhzXLNYPYvdhjyZBvBeGfOpZZwNNS747TM=; b=SbYJdguSz5XSGnzfSNldmxQuA/ h4fVXvg7kI9U710wFHAQ7kHfvh/bf+UqFTrzJlNti45Ho4P7l7jbMmcSRK9jow6Vr2unb9MKTTzXt TsWXXkIiUengvXrphwDWWvDK3zZs1ID0EqtpSKIRQSnHCazIB+uN/4Z79eUfPnee/REoGhsbXwGSe 92kyQ1sQHMIo1xlsQr4P39NtKyHzpevcQFSphoXV9DvR0aHK/DECskAy9X50lcU84bW0rxdl2XROG xSA/MsYttwupcgFTrweSQQ4Z51lFq3M3HYoefXcHPjY8WQWbJv3zR1L1CgGoyr7SeS2aQJwDGv1td kIZ3hcvA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1weB03-0000000EXWJ-1Pzq; Mon, 29 Jun 2026 12:22:07 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1weB00-0000000EXVa-0Csn; Mon, 29 Jun 2026 12:22:05 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id E5ACE68AFE; Mon, 29 Jun 2026 14:21:52 +0200 (CEST) Date: Mon, 29 Jun 2026 14:21:52 +0200 From: Christoph Hellwig To: "H. Peter Anvin" Cc: Christoph Hellwig , 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 Message-ID: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7d8efc7c-65e3-49f8-9381-910de7affef2@zytor.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260629_052204_269255_B87E7E4F X-CRM114-Status: GOOD ( 18.67 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jun 26, 2026 at 05:52:18PM -0700, H. Peter Anvin wrote: > On 2026-05-19 01:24, Christoph Hellwig wrote: > > > > raid6: rework registration of optimized algorithms > > > > - avx2 instead of avx512 is probably the right thing for no > > benchmarking, but if it was intentional (it wasn't), that should > > be document. So I'll just switch back to the previous version to > > keep the state of the art > > It is unlikely to be the right thing *going forward*, though. > > The very unfortunate performance inversion is likely model-specific. 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. This is just about the case where the user explicitly disabled that benchmark-based selection.