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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 054F6C77B62 for ; Wed, 5 Apr 2023 16:37:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232690AbjDEQhZ (ORCPT ); Wed, 5 Apr 2023 12:37:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42552 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232558AbjDEQhX (ORCPT ); Wed, 5 Apr 2023 12:37:23 -0400 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E8CCC4C1F; Wed, 5 Apr 2023 09:37:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1680712643; x=1712248643; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=0xErBa/ZTd4QuIygEuCmz4Ddp7YfQ0AoZ3dVIG2ez3Y=; b=dqLPk3bQ9PiFQn0zDY+AcZjtRALJZLymqJ4MJ4H9QMKAMOhpd8WOcXId k8Hf8+rgp+Z9K7SytT0q1mK5gw1d8TiO59HJfrKBwaf3Ffu/xBXejZc5M 1CMxxfS8HdphHR60dFj3ZWKdWUEOaBFZ8wF/LRaiaTsD5QU7PzZzVwNxv ZqCUYGItOeP3xk/3Ed6MvLguxuRN9XP+gDmYljboI1X1P5bjtsN5QuS9g mz1Vde2rXtnqNox+BC5E/d4/hW4YoMlhq311JQWEDB6ZvqP3Cb+hd0T2x xI4aUSmEvHngGnTNoQVFY+0+jF/VkgQCEE4xCX3DM1kEDdkimHQX98SoS w==; X-IronPort-AV: E=McAfee;i="6600,9927,10671"; a="339995929" X-IronPort-AV: E=Sophos;i="5.98,321,1673942400"; d="scan'208";a="339995929" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Apr 2023 09:37:22 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10671"; a="932891908" X-IronPort-AV: E=Sophos;i="5.98,321,1673942400"; d="scan'208";a="932891908" Received: from kyunghyu-mobl2.amr.corp.intel.com (HELO [10.209.6.69]) ([10.209.6.69]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Apr 2023 09:37:05 -0700 Message-ID: <7360ffd2-a5aa-1373-8309-93e71ff36cbb@intel.com> Date: Wed, 5 Apr 2023 09:37:04 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v2 0/5] locking: Introduce local{,64}_try_cmpxchg Content-Language: en-US To: Uros Bizjak , linux-alpha@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Richard Henderson , Ivan Kokshaysky , Matt Turner , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Arnd Bergmann , Peter Zijlstra , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Will Deacon , Boqun Feng , Jiaxun Yang , Jun Yi References: <20230405141710.3551-1-ubizjak@gmail.com> From: Dave Hansen In-Reply-To: <20230405141710.3551-1-ubizjak@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On 4/5/23 07:17, Uros Bizjak wrote: > Add generic and target specific support for local{,64}_try_cmpxchg > and wire up support for all targets that use local_t infrastructure. I feel like I'm missing some context. What are the actual end user visible effects of this series? Is there a measurable decrease in perf overhead? Why go to all this trouble for perf? Who else will use local_try_cmpxchg()? I'm all for improving things, and perf is an important user. But, if the goal here is improving performance, it would be nice to see at least a stab at quantifying the performance delta.