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 B9747C55174 for ; Wed, 5 Aug 2026 06:12:41 +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:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=1hLSDYK85M3wvI1xgsH2onhHuYsbD0hLp15Rb5kZzBE=; b=DKrN87fCfgHVD8JNpogs9J41+d 6JzX3qtq3joHAT3EWh4QhzWjZb9/ATlbKxWbwtYhMHJ56gnDYpAUkFEzsH+WQuTY9fJ0vzAX6/BUK r0lF0FFUzpJvvH5hq83e7rnMpFootxYiDuV3zz4njY1HfLzC1lnf2NdvuGaL3cEwXlDAoZ60S66LB LNfEdDA481nkAvEdYOAd11VfoY2A3ZnH0hmc9AxdMJq4m3i9yTpl+eQJF+cy7u4Kjy0mNGjmIQ0uL mNYH+PWqaFfs98jmfOp4MVCND2EKRJdMeo6+b9jbb2eJW28DPUuMuprOHMzrEAysJiIoG69KW5AKQ LcuDjVig==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wrUrc-00000003HxN-1e5d; Wed, 05 Aug 2026 06:12:28 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wrUrb-00000003HxA-1V6C for linux-arm-kernel@lists.infradead.org; Wed, 05 Aug 2026 06:12:27 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 37141600B1; Wed, 5 Aug 2026 06:12:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 875871F000E9; Wed, 5 Aug 2026 06:12:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785910345; bh=1hLSDYK85M3wvI1xgsH2onhHuYsbD0hLp15Rb5kZzBE=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=nuE1953L+3uAi2FMf+5JWzAAPNWofIinBa7crSNrCgsraRRSMNncnBoftKUUhA5LL /XIkABmVioCXWD4/nqjYmth/a1BqShCVNeIs7MmkY6QKmNe6Dvi3MLmVkn3ZW8hp4r J1JZnb8ds2VXplLPxeIVmoCSL4Fg7LHyb2LyBN0peX6uskmvX2dh3QvTH2gYNSjJsO 8Zp2JJSrNU+DR4D6sh2qRdh8Yz+JWGD+C/ptATgjG917Ygf+zbXpdqYGkbZe0pJynV 5DJCfmXRCnd5OH1mNCKU7fwmztu2DGU0+YCUuG0hbBKL1otTwnPAT8MvOcZWn9Y0nD ckE0cMYWtKaww== Message-ID: <3d5f0435-59a8-4eb8-825a-d8451c6dfb81@kernel.org> Date: Wed, 5 Aug 2026 08:12:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC v2 PATCH 0/16] Optimize this_cpu_*() ops for non-x86 (ARM64 for this series) To: "Christoph Lameter (Ampere)" Cc: "Lorenzo Stoakes (ARM)" , Mark Rutland , Yang Shi , Ryan Roberts , dennis@kernel.org, tj@kernel.org, urezki@gmail.com, catalin.marinas@arm.com, will@kernel.org, akpm@linux-foundation.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Linus Torvalds , Jason Gunthorpe References: <20260715180455.515692-1-yang@os.amperecomputing.com> <0344c559-1959-4531-9265-d5a5180eb7cd@arm.com> <25d1e09b-53e4-7cd5-87db-b58437e4e690@gentwo.org> <4887267b-dc26-4c33-96ca-8dff054a0d1f@kernel.org> <63ea8156-a109-b2a2-6d35-1c17ad7f1a9d@gentwo.org> <84b31836-1d10-4bec-a469-468b91fd4645@kernel.org> <9f146ce0-4adc-0c00-a2d8-c01b47edc9d1@gentwo.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit 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 8/5/26 00:01, Christoph Lameter (Ampere) wrote: > On Tue, 4 Aug 2026, David Hildenbrand (Arm) wrote: > >>> >>> You cannot accept that one instruction is faster than the same >>> instruction prefixed with another and something else at its tail? >> >> I am pretty sure that you got exactly what I meant, you likely just don't have >> the data to back it up. >> >> Proof me wrong! > > Well you seem to have alrady seen the benchmarks that we ran and are > running. So I had doubts on your sincerety with this comment. Seemes to be > be just there for effect. Let me repeat a third time: So to be clear: claiming that the additional instructions are unacceptable I'd expect something minimal like: "removing these 3 instructions speeds up micro-benchmark (a, b, c) by X% and macro-benchmarks (d, e, f) by Y% compared to Mark's approach". [1] [1] https://lore.kernel.org/r/ea268481-d584-4744-99d6-0b05aade7d5d@kernel.org -- Cheers, David