Received: by 2002:a05:7412:e79e:b0:f3:1519:9f41 with SMTP id o30csp208271rdd; Wed, 22 Nov 2023 13:33:02 -0800 (PST) X-Google-Smtp-Source: AGHT+IFGZTeTRKfHL+vNa8iUhlOdYxugE+sA8Namw5g00LrHqrtSVLLD2fCBEkyZ57M2SfF19KDQ X-Received: by 2002:a05:6a00:3915:b0:6c3:6cdc:a297 with SMTP id fh21-20020a056a00391500b006c36cdca297mr3815679pfb.14.1700688781721; Wed, 22 Nov 2023 13:33:01 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1700688781; cv=none; d=google.com; s=arc-20160816; b=Lc/ipEe54sNrR00kXvri0rMhDnu92lxf2jAYQptKr6mF2I/VsPTb/yKYSd9FuzjJLE CroX3lwQsFHcgtBexTwd7M+S8R+HzeS4S62iw2SkYPzEpUPAS6b6DBXP60baCKW1s+wW YFJgWfRcM+gzXrv/W7c3gocMwX9UEtkAMzmGL2Z2nwZuD7OiNSRM3ONActEtH47ygG10 mLL8/n0z8+X1mQYFT0HC1GT7q/yTpxY+Pe0XICdiUFJI6SgHAOzcndh2n7XlRTLoreeG nJuSy2cHBiioQuojiV8hlAC/bIAkg2B+xBHSzu7TMe4F4FTk+UZxacNzaD3pZ0JA7mou iZlg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:in-reply-to:autocrypt :from:references:cc:to:content-language:subject:user-agent :mime-version:date:message-id:dkim-signature; bh=ODObynOeqRMrFMlkAeQz0cXD4MJ5fzZFbzWyNpWb3L4=; fh=phv1qhA2fE47Ssumio3q6gPx0ikEL8DXKX2Wd9NdR28=; b=GwqKmi1gm8e2euIhJGp5CHa9kl1lpiSWkKuIDcL8Q+C+NCXcZB/RsfhsLOLpf32dDd BMHGp279l70nJEPaH/M+Sh8KvBvu9gfyRFOL/VBVH2JyqEOI+eYd8tigEbGpBzWLQ668 D/OiyHycCCrUf39FOKW3Vvc947Kqo3foxBKsyFWgjnT8VIMpFtjb78nbD1jEDlQDiQfq aPuU4c0d7Ag2AmTToWdzsIbHO9RyMDJJRl80/vbKDLJn74YaMfzZ4GdOL+IcT2gxExmv CgF63erA3AXXEYN5is8m0+dOP+DieQ8ls9W0XdmaDTx6TGYly55FXKfA8ZOpp4vosS61 iTKQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b="IgM/9N+T"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Return-Path: Received: from lipwig.vger.email (lipwig.vger.email. [2620:137:e000::3:3]) by mx.google.com with ESMTPS id j11-20020a056a00130b00b006cb3b40c542si355992pfu.90.2023.11.22.13.33.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Nov 2023 13:33:01 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) client-ip=2620:137:e000::3:3; Authentication-Results: mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b="IgM/9N+T"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by lipwig.vger.email (Postfix) with ESMTP id 34BBC8255485; Wed, 22 Nov 2023 13:32:59 -0800 (PST) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.11 at lipwig.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235154AbjKVVcv (ORCPT + 99 others); Wed, 22 Nov 2023 16:32:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52634 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231648AbjKVVcu (ORCPT ); Wed, 22 Nov 2023 16:32:50 -0500 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 732A71BE for ; Wed, 22 Nov 2023 13:32:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1700688765; x=1732224765; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=8kpykWlGrg6+fxnqHu1JQdZFlpRwiPc4EdWzsrISrbc=; b=IgM/9N+TAGG+M3M1h1fE46/gUcwyyr85rgflp/DP+NsyS16+rrBgRN8I aLg1y4VAaq5yCzr9EZO0L9eBHX6jk8UgZC1K8GBTBnpeCE3iSwV3Wf5aT /FUVwdxrdd3PMnHOmU5gOb3LPA2s6AxfP95Lr634FZUyJa6BMknRu/xrU sdfVuyrIx/U2XuLNXBLPSTWMSOZb4LA7Ng0NCLzGtmt+Dl8fU1VIGyDz3 RqMeXia1zx3BB22Ma67xaAWgOY3wYxZ25QHwejjpVslr6LfdSZSMqNdY7 8T7zMPrG76ZlKP8kZSnX90QSY5uh9KeZmPJuKHA58H8YMO2j3m/4ia8uJ g==; X-IronPort-AV: E=McAfee;i="6600,9927,10902"; a="10827508" X-IronPort-AV: E=Sophos;i="6.04,219,1695711600"; d="scan'208";a="10827508" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Nov 2023 13:32:45 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10902"; a="940407952" X-IronPort-AV: E=Sophos;i="6.04,219,1695711600"; d="scan'208";a="940407952" Received: from ejoyner1-mobl1.amr.corp.intel.com (HELO [10.209.105.19]) ([10.209.105.19]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Nov 2023 13:32:44 -0800 Message-ID: <7aaa343e-365a-4c87-a139-7d26bbb50bd7@intel.com> Date: Wed, 22 Nov 2023 13:32:44 -0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86/smp: Use atomic_try_cmpxchg() to micro-optimize native_stop_other_cpus() Content-Language: en-US To: Uros Bizjak Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , "Peter Zijlstra (Intel)" References: <20231114164416.208285-1-ubizjak@gmail.com> <367bc727-3f26-4e78-8e58-af959760b3fc@intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lipwig.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (lipwig.vger.email [0.0.0.0]); Wed, 22 Nov 2023 13:32:59 -0800 (PST) On 11/22/23 12:18, Uros Bizjak wrote: > I'm not here to discuss policies, but the "don't fix it if it ain't > broke" policy is a slippery slope, as it can lead to stagnation in the > long term. Please read what happened here [1]. > > [1] https://lwn.net/Articles/488847/ Even though I'm not dying to apply this patch, I will take a look at it again if it improves in how its changelog is phrased, actually makes the code more readable and comes with some kind of statement about how thoroughly it was tested.