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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 204D2CFA47E for ; Wed, 23 Oct 2024 21:41:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A9B046B00A5; Wed, 23 Oct 2024 17:41:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A23CD6B00A6; Wed, 23 Oct 2024 17:41:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 89D906B00A7; Wed, 23 Oct 2024 17:41:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 6C17A6B00A5 for ; Wed, 23 Oct 2024 17:41:35 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 3362B1A0EF5 for ; Wed, 23 Oct 2024 21:41:03 +0000 (UTC) X-FDA: 82706188404.23.9AB1288 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) by imf28.hostedemail.com (Postfix) with ESMTP id 15C5EC0023 for ; Wed, 23 Oct 2024 21:41:14 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=zytor.com header.s=2024101701 header.b=Ru8OEuvY; spf=pass (imf28.hostedemail.com: domain of hpa@zytor.com designates 198.137.202.136 as permitted sender) smtp.mailfrom=hpa@zytor.com; dmarc=pass (policy=none) header.from=zytor.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1729719542; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=bD0HK2j0SgBCID4Iw/rZZNpJTyJpExrZmV8kuJQazzo=; b=WpL7dP6CYCfM770/9xqLzLELcacGhhQthGwo6LxoLWk3xE0SgdtaWs/79zFrt5o3lN58lo pEB614k3J32pdSn9jsezo5fD+XuFCsihwmkssLSvokkFoxpF0X6Id3z16oC1EGZJfRhUr/ FtN2YJEhJrStumSv05tpcM9Ml+FSIUE= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1729719542; a=rsa-sha256; cv=none; b=goyY1YD4R7xO4T6VXmyBtX6tkdnWmQJFTAHLyqwN6OuFhno6XZ/T8pVOmhIx/ThteQeZMV PDRByZezKu+d1gGvG+FFAdzf4V137IEAeyfokirofUoGSVeARABTlpnKUAB69udXa4QIzW AGIkrfNnCnctr2pS2TkWs/CKXzJrJBk= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=zytor.com header.s=2024101701 header.b=Ru8OEuvY; spf=pass (imf28.hostedemail.com: domain of hpa@zytor.com designates 198.137.202.136 as permitted sender) smtp.mailfrom=hpa@zytor.com; dmarc=pass (policy=none) header.from=zytor.com Received: from [172.27.3.244] ([76.133.66.138]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 49NLexNv1411797 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Wed, 23 Oct 2024 14:40:59 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 49NLexNv1411797 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2024101701; t=1729719661; bh=bD0HK2j0SgBCID4Iw/rZZNpJTyJpExrZmV8kuJQazzo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Ru8OEuvYgotG68bpU1jy5B2NhwpTi60EKtvz/WmX2nl2K0CUUMLvyQSxCWTWJT1ia 8/9H2rGjgd/Jq71UH78VZKB9SBhlbLTnV6Nt75oIgGcW8ahyBxJF6gZznS8ObG7+11 HBJCHCgW8J4ZxwmFL9Y4BhQUfGi//nLpxAv5Dxb5BbmAivTxgqVl2gFPG1pYn7dH3a pRMWpnJH8JWijyjWjGz0pWXC8oU7OISbUcrN4Xm/3ocjRMbYf0Xf/tI4cBCgjBirGg oV23LZZvXfSK5N8YQz+45gs5+neVUVtDZwGH8lJP2KCFeYeaTHlzf/4ii6QqutY/gj FPjIs/vi9ZWqA== Message-ID: <20ed1295-3012-4d71-a4d3-9d6a63cdfdf3@zytor.com> Date: Wed, 23 Oct 2024 14:40:59 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 1/1] x86/percpu: Cast -1 to argument type when comparing in percpu_add_op() To: Dave Hansen , "Christoph Lameter (Ampere)" Cc: Peter Zijlstra , Andy Shevchenko , Ingo Molnar , Uros Bizjak , linux-mm@kvack.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Dennis Zhou , Tejun Heo , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt References: <20240905170356.260300-1-andriy.shevchenko@linux.intel.com> <20241016192011.GY17263@noisy.programming.kicks-ass.net> <20241017181859.GB17263@noisy.programming.kicks-ass.net> <4b1a26b2-cccb-75d8-ee2f-f30ae211e598@gentwo.org> Content-Language: en-US From: "H. Peter Anvin" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 15C5EC0023 X-Stat-Signature: a4w4p17g6s6mm4xmtjnbq9uad9uyk6hg X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1729719674-529316 X-HE-Meta: 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 MVGOWjU5 sqZKKuJzDBhjMrRNARw+QhyrZZ18i6DlP5hnn16qwHejyFkKqi02eLZ4VxklyDJVTBomFtz1DBDfWk4tFxoNb0GCJNMQNaEA+vQUrr8d5PpWaoQRKDVy5oqDnYmMSkdbgdtZIKHcsVVoI/vfbiriUxIi8e6JnvtakBr2ZsHYDS5o6bmiX/XhJVOrNDbKM5/kxVbB5XQA6G5F/mZKZ9e3hBqZs4yjqgtqJBOqOdfEaAFv2KvzlxFwi9R3ik4sxywlacnNUBEpOUF+bDBjWnY3EfLdneasYI0rG6lQy7vnwmqQRIy3D9KitN9w2M9U4uYSfKZ5jcfiVQyY+HGU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/23/24 10:15, Dave Hansen wrote: > On 10/22/24 16:24, Christoph Lameter (Ampere) wrote: >> On Tue, 22 Oct 2024, Dave Hansen wrote: >> >>> So I think Peter's version was the best. It shuts up clang and also >>> preserves the existing (good) gcc 'sub' behavior. I'll send it out for >>> real in a bit, but I'm thinking of something like the attached patch. >> The desired behavior is a "dec". "sub" has a longer op code AFAICT. > > Gah, yes, of course. I misspoke. > > We want "inc" and "dec" for +1 and -1. "add" and "sub" are heftier and > get used for everything else. Do we really? I don't know if there are any microarchitectures where the partial register update still matters. It is only one byte difference. -hpa