From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gentwo.org (gentwo.org [62.72.0.81]) (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 EB033329395 for ; Tue, 4 Aug 2026 22:32:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.72.0.81 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785882756; cv=none; b=HtRqqxhgIE55gJv1F4cOEfX7lUCkbDOe6BDdpb0UWyBuAaJDJW0O9TqA/qJZvTZ5iVV3RAlJmUG1zZNbGW0atBCGy1t2y222Y8fs6AanYHajhvjjZdyluZ3UP58z7WVKXfTB5UWrQMiyiYgB5Rk6vtBHwCH/8LC8DK5/tXhYNo4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785882756; c=relaxed/simple; bh=4i1mGJ+FRQRfIxKQvXxnnfkifi+5HFhjIAJsj6nqa5k=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=QW53f4IPtVURTHPwHdB83OKuuyOUUWGMykkNKo/dP8eRhr166YY1UzEXFBsvlJuKnxV8NgYgZ9GnKfDn0sIkdQJ+/9uQEKRA46GsRvqhHi5UjZE5ijfe/BTlaS5fILu5Z7wbbLuxhIkl44ibSXpcCOvRHGCvCf0L5EL3bkGtHLg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=gentwo.org; spf=pass smtp.mailfrom=gentwo.org; dkim=pass (1024-bit key) header.d=gentwo.org header.i=@gentwo.org header.b=at2yiKLY; arc=none smtp.client-ip=62.72.0.81 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=gentwo.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gentwo.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=gentwo.org header.i=@gentwo.org header.b="at2yiKLY" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gentwo.org; s=default; t=1785880881; bh=4i1mGJ+FRQRfIxKQvXxnnfkifi+5HFhjIAJsj6nqa5k=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=at2yiKLYfZC3fVakZoWLhCksz0PMrkI6/d0TYKBPoXpIGPtfNc7LU+ViWv+A6CxMf GC7DQy0jW4XLySRIheErfnG9B0tvk7yE/mUQWds+3h9H8PtzC63PmrbXcK6D3O7ooq 2NcakzJJtfeuENJUfR891WT/5jvSHVkQBfAfP5dE= Received: by gentwo.org (Postfix, from userid 1003) id 2788540E6B; Tue, 04 Aug 2026 15:01:21 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by gentwo.org (Postfix) with ESMTP id 264D540287; Tue, 04 Aug 2026 15:01:21 -0700 (PDT) Date: Tue, 4 Aug 2026 15:01:21 -0700 (PDT) From: "Christoph Lameter (Ampere)" To: "David Hildenbrand (Arm)" 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 Subject: Re: [RFC v2 PATCH 0/16] Optimize this_cpu_*() ops for non-x86 (ARM64 for this series) In-Reply-To: Message-ID: 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Tue, 4 Aug 2026, David Hildenbrand (Arm) wrote: > >> If the proposed solution has a significant benefit over Mark's solution it could > >> be discussed as a next step; and it must be backed with sufficient data to > >> warrant all this complexity here. > > > > 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.