Received: by 2002:ab2:6816:0:b0:1f9:5764:f03e with SMTP id t22csp2247965lqo; Sun, 19 May 2024 22:21:49 -0700 (PDT) X-Forwarded-Encrypted: i=3; AJvYcCWSzxPSHUpv/1Hs9w5GcTu6OUe5ZfYWhTQGw3/byGPyz86DYBQ42WStzGTnIdPXoHAR9ibxi/dGkqgeQxPJwK57jiRZzaXReblWbNcSwQ== X-Google-Smtp-Source: AGHT+IGG+airwmsCxmKGEt8beUYrMfBQKDKLBfXQPLwq2/YWaWIzCdQgbFwY8l+qhWrCNL+ZJwk9 X-Received: by 2002:a05:6a20:1590:b0:1af:939b:d477 with SMTP id adf61e73a8af0-1afde12444bmr33070366637.36.1716182508763; Sun, 19 May 2024 22:21:48 -0700 (PDT) Return-Path: Received: from sv.mirrors.kernel.org (sv.mirrors.kernel.org. [2604:1380:45e3:2400::1]) by mx.google.com with ESMTPS id d9443c01a7336-1ef0bad62d6si28596925ad.144.2024.05.19.22.21.48 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 May 2024 22:21:48 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel+bounces-183417-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1; Authentication-Results: mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b=Ipd7GUZx; arc=fail (signature failed); spf=pass (google.com: domain of linux-kernel+bounces-183417-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-183417-linux.lists.archive=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sv.mirrors.kernel.org (Postfix) with ESMTPS id 13E1D281791 for ; Mon, 20 May 2024 05:21:48 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id F142813ADA; Mon, 20 May 2024 05:21:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Ipd7GUZx" Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) (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 BB3EE33C7 for ; Mon, 20 May 2024 05:21:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=192.198.163.19 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716182502; cv=fail; b=FxMXlkR1j2XGCJjGWn4IPhR/uQ/4GxWD5h8YKYbPy9+bfCVAxaoVelbK+wpO/Qzvs6G3DR/KheimH3LMAb/lHctsm3qT6IPaifoA3T3EJigwl+/ilEIWD0EkOxfXJB+7VqsXTkGSUOgkGKD5WPvHHLsQ3DZWPACOfEw3psb7lJ8= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716182502; c=relaxed/simple; bh=ZsmfZ3nJY/JxXcSCiBZsZc+hc/NUBmZmRx3Sm4tMwpg=; h=Date:From:To:CC:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=LgnDXGwOnasKQk2e1B8bBUl68/QgJ9mFuleAcAD5NL0iBbXQ4ZNVkARjuAgkaEXzWKHo+n5z+XGHpHxlUXAD2yMZ75e2DSob/H/+BBZKhASJZx1y6zV6ER9vsU0LsHmcEFk+L9dX9qo0UtQA2OhCkDWcEjqDwNIbyax5vQ5nZdM= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Ipd7GUZx; arc=fail smtp.client-ip=192.198.163.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1716182500; x=1747718500; h=date:from:to:cc:subject:message-id:references: in-reply-to:mime-version; bh=ZsmfZ3nJY/JxXcSCiBZsZc+hc/NUBmZmRx3Sm4tMwpg=; b=Ipd7GUZxftImQNwiMnCB1D7IV4D3I5BlKe5S44rsLeDjh6a6Gcj6BLcM dAUSm92Eqz2dwqq/X5apriwulY49p7+6FaOiCB8yi+evzlDamnhSW4D0G thxXI5vX/7RM+knHmRK/r7obtnBy1qyhHblOv644E6EHZjd2bcLZHMbql KtodxvTsEPFpXnnvr5bGCN1T75Qhy8+Pe2WFv+XPaZq4TkqWjcQdlvotj mduzVahyijnTyqPQPhX4Ae0UCOcSb47KzFST8szQN6CyGYuf9X7Z1Exf7 NyJ32F/zH64QBnJbq8tUPD/KsivTZqiS5yhm7NauMaQxjUDRn3w8XonEz A==; X-CSE-ConnectionGUID: QSN4ZEKTQ5mYZ8WvziwDHA== X-CSE-MsgGUID: 5iAJcJkuT1CVm5KLVL91rQ== X-IronPort-AV: E=McAfee;i="6600,9927,11077"; a="12139281" X-IronPort-AV: E=Sophos;i="6.08,174,1712646000"; d="scan'208";a="12139281" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 May 2024 22:21:40 -0700 X-CSE-ConnectionGUID: J7bgapjlQn+YRVjSfrZUhg== X-CSE-MsgGUID: Jn7Q7M+CSFCBIFJOT9xTxQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,174,1712646000"; d="scan'208";a="32839055" Received: from orsmsx603.amr.corp.intel.com ([10.22.229.16]) by orviesa006.jf.intel.com with ESMTP/TLS/AES256-GCM-SHA384; 19 May 2024 22:21:40 -0700 Received: from orsmsx612.amr.corp.intel.com (10.22.229.25) by ORSMSX603.amr.corp.intel.com (10.22.229.16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Sun, 19 May 2024 22:21:39 -0700 Received: from orsmsx611.amr.corp.intel.com (10.22.229.24) by ORSMSX612.amr.corp.intel.com (10.22.229.25) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Sun, 19 May 2024 22:21:39 -0700 Received: from orsedg603.ED.cps.intel.com (10.7.248.4) by orsmsx611.amr.corp.intel.com (10.22.229.24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39 via Frontend Transport; Sun, 19 May 2024 22:21:39 -0700 Received: from NAM11-BN8-obe.outbound.protection.outlook.com (104.47.58.170) by edgegateway.intel.com (134.134.137.100) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.35; Sun, 19 May 2024 22:21:38 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=MbA+1Xupvn5WfpiPIrxwWfta2kVFG1zKrWJxgmLpW6K2qDMYW4x4lSPB8OZigq/L+WcwaMOSamXrNPnNjqkZctYXaSdHwz4MfaHRSeTCKr626K156/VkqlWahm8X9x9j5mIXpOr6VZ7D6+pexjjwGtNFGfuRbhc+CK2pp8MhYxwtvC4GgZuxmJTcOwS6chRg4VCGjfZ4L01pzEeM6cHflnh1bMiYNR+HkvJ54DuUfMOt2XYYkuFWddHd9APAGEVYUEQNQmEjgVJFejzz5bAphpGDCNTOzIQBXXzEEXlD5nufMyc5RteqOca7EsI5aymefBs8F+0c3ydp6/UfCrSb3w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=QMG3XcHSaOI9XWJ1r9CM2Jux1nGJzVHukGJtd/QqHno=; b=IWh3o4czGIx2C7Dz7CfX2riqFpzuPZzRP5l/3BGYrBqBcdWyxgsqtPTgaplXS1FM70Ndwd/TR7gCfp14g8MRT+DGs/tRlAu74+jm68Qi5hh4A4QuDW8eJ3SsPDa6xNUpu1Pa5O2uEA15doKNDR9m5X84IY4InIpXegqQoDESBVGxVRYtmB+lxHiUTElpft35KJ+M9mQqMRCUkjSYmBYAdoy5euWvGL1wUDgXexKoecV1AhloPIfMpaAupBdmy9FLgqPwim8i0HrRCiMRQ9wwmb35pYiHCkosPHmUfenLdm2EIthalDWtRFqmK+jXWXEj6PmnbLrPBaOw6FQ8xXe4Qw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=intel.com; Received: from SA1PR11MB8393.namprd11.prod.outlook.com (2603:10b6:806:373::21) by DM4PR11MB7758.namprd11.prod.outlook.com (2603:10b6:8:101::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7587.35; Mon, 20 May 2024 05:21:36 +0000 Received: from SA1PR11MB8393.namprd11.prod.outlook.com ([fe80::1835:328e:6bb5:3a45]) by SA1PR11MB8393.namprd11.prod.outlook.com ([fe80::1835:328e:6bb5:3a45%6]) with mapi id 15.20.7587.030; Mon, 20 May 2024 05:21:36 +0000 Date: Mon, 20 May 2024 13:21:32 +0800 From: Yujie Liu To: Josh Poimboeuf CC: , , Linus Torvalds , Daniel Sneddon , Pawan Gupta , Thomas Gleixner , Alexandre Chartre , Konrad Rzeszutek Wilk , Peter Zijlstra , "Greg Kroah-Hartman" , Sean Christopherson , Andrew Cooper , Dave Hansen , Nikolay Borisov , "KP Singh" , Waiman Long , "Borislav Petkov" , Ingo Molnar Subject: Re: [PATCH v4 1/5] x86/bugs: Only harden syscalls when needed Message-ID: References: <982d05a2f669140f26500bee643011896d661094.1713559768.git.jpoimboe@kernel.org> <20240507051741.4crk2pd2fuh4euyd@treble> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20240507051741.4crk2pd2fuh4euyd@treble> X-ClientProxiedBy: KL1PR01CA0043.apcprd01.prod.exchangelabs.com (2603:1096:820:1::31) To SA1PR11MB8393.namprd11.prod.outlook.com (2603:10b6:806:373::21) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA1PR11MB8393:EE_|DM4PR11MB7758:EE_ X-MS-Office365-Filtering-Correlation-Id: 9f7337d0-945c-4598-a1f9-08dc788cb80a X-LD-Processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230031|366007|376005|7416005|1800799015; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?KQSEihKQu1MgZ1LGf6xRKQ+NFVqcwoAZcCWnpOv2xqcvh0OB4X06Htv55bVM?= =?us-ascii?Q?St3/j+Td/oGXE5WDWErLK0w6XLJhqAdgHVINl+xoPQJFqzt/lA25gJGrwq+y?= =?us-ascii?Q?+P+cggpTYgTtMygPjvX0YX568pGeo4k90ADrjVJqrZHrFmt5KH4hvNFJ016I?= =?us-ascii?Q?zAKTVsM6fjXIU+k37BPTDk+8t0+33GhS06Fxtd/tJR9MZspCeOMZb3AAXw0E?= =?us-ascii?Q?LajhKPNQhBC9uZrcKx6ZD8pyfUGJBA1/ovUMlOexQF+89j6BlA2636e/ff9W?= =?us-ascii?Q?3mbwaOR3tGI9orGBv7seCbONnZtfs6vJGDmzlQp9ghskp7GAQSF+04u1jwlo?= =?us-ascii?Q?GMa7p7pTOJyNqDrnA5zsXkeUh6am2sMdkLNY+DIH0HIrK1AKEQHJ3xP3ACmN?= =?us-ascii?Q?Xw18UMj5P8Kq5kkciykRszlMDvN1MYAeSfxS/AJtdatCItqYEirtrvw65tQD?= =?us-ascii?Q?1fXyoxkMBUSBxIid7oU2M2Q2coqmyyNDzR0LFgPo0nGDmbnAYsPBb68JEiTh?= =?us-ascii?Q?nJ5Ha1RPR2iy35fGrHeiFCmVQesRDU0uDvhUBTP3NSkAk4rBaUplnCO9Il8f?= =?us-ascii?Q?Uc68AZJ4Cj6zbiRT/a1RAxKUdPqBxnr0/GA7IokE4d1RRTmtMygltaOZMNoO?= =?us-ascii?Q?WUdHc5RW+m+7Fa45UzbiHFEfxt7B4HSPaKrk1+XLzW9HMliHQ3YiZarFFp4k?= =?us-ascii?Q?XYsF6NnK2chmjt76M0fV6jv5KwFnkFw1tXjXG9oi/a/7+nFdOOmQ8KT1QCX0?= =?us-ascii?Q?t1K0GWNMZ0qR2LS9B3pPm5IVE8nTELCEtlnEHK+RB856k2dUiT1c8HhA/1nD?= =?us-ascii?Q?d7eBLEjNB9CuoLRj2Q3iA2394+2kTwErOlaEFROE+bkftWk2SAAFe92hqIRS?= =?us-ascii?Q?+jLkpjyk0l/qVYzetsmRAm7x4UNeXEygLuBFa2n3QtQtjFInfn+qbrtPGsD7?= =?us-ascii?Q?EFf03qjx7COesvUaWM8veKAXz/utXCbC2Hsq8V+KSQTF0ghLJ9hUvWOvE91+?= =?us-ascii?Q?F6Ubc+EBxQLnuo/h9T536guXmetMMmXY+7lmZg9sddkS5R488vIXAeOmvagE?= =?us-ascii?Q?pjoQlqPEcltr6fq5n24ICZZLzSo8yFbcku0BFGbwGNeQE8e71HdwMF6thqvs?= =?us-ascii?Q?QRI9glD7eX8t4BFjf7CZH4oIPlx/0DV+MbZKfpE4/7YoLFuRQj7nb1g+SVih?= =?us-ascii?Q?aDoipUb7kMugOIq2huTm5u2zz1HNv5oR4Pyv6g=3D=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SA1PR11MB8393.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(366007)(376005)(7416005)(1800799015);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?G4WmQLBLH4785qiqUQaAQwT+mAOlz6baYUWDS2nImX1GzWzCAiglad1h+rit?= =?us-ascii?Q?MTpzXKg6Vaeb1J0TiEAdTvqZJsVL/gOZUHeib1jiLokjYLsZRrz3qKqvj84x?= =?us-ascii?Q?Fx4gK1PuT9QRc0q/9XaZWoL8DV5QNGjcihkOjB8MfNsERL/iHJRa5Upy1rAW?= =?us-ascii?Q?JGZGUYYHz6P5s0ogw8Bcuxz6fcUx2gauwn123zjlning3yKoRBN2WSz/G+Sc?= =?us-ascii?Q?7JPGEWOyHKsg+GT6WC35ycjCb6BufHtqJRuvdf5TJvE5SJFE703ZIi40a1l3?= =?us-ascii?Q?cjfsqCkaZdQ309XGWi33G3whC2hespckl5AqHPSdzkgJxXkuPFU9egWcFgmW?= =?us-ascii?Q?Y5Zo5ycsEqGdmbnRhe9aE6Rk2yXfdQVQlAHCbtFMkALIYl5yi9A+F1iRokjZ?= =?us-ascii?Q?s5xbTegQxeKhqTTbxvwNw89x6z/aqFtGQ92yScUR+KBRLCwUtiMkubBxpukD?= =?us-ascii?Q?9y+wI0MDG1gpl2EhtTQqWbrzXd0kKxBWJFiWoTIO/pQoJ1ESa9NQ2z7yH2mh?= =?us-ascii?Q?tMrnTWNf6YKTjDcBckOi+DXOb1Ci/7qQxBJFAVdy1KBZ0dxRyKzVV3GrTcZM?= =?us-ascii?Q?BvGW3Mt24tsugNKY79feaK9LZ1wSpDRfY/x1Hogx7mkJYd6nzI8mahlbwU2m?= =?us-ascii?Q?6fLl66PWrIvW6RpiRn/LCdYJStKeD84LfCm+BGsX5FxPpatX7unZ4W5B2l5X?= =?us-ascii?Q?fQG03OnT+NRvD01o0fAd3nW5Ywu0pXv0Fa8yJpwOTWEoMGPUD9KWdp9/lSVs?= =?us-ascii?Q?KZ11+4o/ANovnfJUlYilM/wAIrjl1POvKIoVr++84SwrMOWjHKoABtAliuaT?= =?us-ascii?Q?Uw9SdDDuDtTjb3FLeWy6b0jroE5YMSG5qMY2FS1tDpxlf5mR4Ev3UsqcZ0uA?= =?us-ascii?Q?UnUqtSoQTiTOw7p6o/kYBSwIFiSWTQXnZ8Afk7GCbGyEo9/rZRzaO4WLSRYM?= =?us-ascii?Q?tn4qjDo3N54vyPDRV4tM+jH7Osg7E8mTNRS/n3caK86d/hfuX9nDh4/kRNNI?= =?us-ascii?Q?WpMM/rFHVjkiKpHYUujlAP1lu2ZTUqwOG/azJYNkawi4O/J6HmQ0LKcgEfIT?= =?us-ascii?Q?7EhgGmUkMPpqYLQmlDXUOjfAxbktLFZOulTeB6dqAa5JmTM9r1xeexhlH8IU?= =?us-ascii?Q?NRTH1AE3jDxlesmH3iEdzYz/l/CKMMSdqDTktf7vsQmmTXvAuMAywmncfaSZ?= =?us-ascii?Q?tgG4QcROJKoNli0yhxnOG9F0bSekGotMT+PWa/RWBxOQY3nKEdjZNRLEkqsH?= =?us-ascii?Q?NZQfruLWQ1MxyQda2/00bhFyhTh7RPslGfxvQ/1JBH7OZNVkInDLXM6IJD17?= =?us-ascii?Q?RqK4coZijX4Io1kxgaqRxeowp03boEvbpknrbxOgHOZKUMwW5gTcLTt9AuG8?= =?us-ascii?Q?A6GijJ0MkUCjSK2AR/EgQ2nkNuWkjABuBwetO3WEUwVs3hwtxSZaMR2mupyL?= =?us-ascii?Q?LzT0w03/er9Fo3R+Yj4W/+jeu58//Bl3rDeqlw+C9njMicT600Z8/QBU4638?= =?us-ascii?Q?PErONSUq6TXDJlkVYKPm/1V14YWqrggPLjU8un88oFLR2YFYWwl4zYtKuvQL?= =?us-ascii?Q?HQrFWB5YEcW1wjwXGxp4ukngRzL6EfoXGZ4KcX1r?= X-MS-Exchange-CrossTenant-Network-Message-Id: 9f7337d0-945c-4598-a1f9-08dc788cb80a X-MS-Exchange-CrossTenant-AuthSource: SA1PR11MB8393.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 May 2024 05:21:36.1540 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: lllULvm0bnQmMmsCjIxZwDDydVmfE5/rhw90wixvuGOXEDLtI6IItjtFHptsSGh237wQjH7aEKOn2A9I5ZtZLg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR11MB7758 X-OriginatorOrg: intel.com On Mon, May 06, 2024 at 10:17:41PM -0700, Josh Poimboeuf wrote: > On Mon, Apr 22, 2024 at 04:09:33PM +0800, Yujie Liu wrote: > > On Fri, Apr 19, 2024 at 02:09:47PM -0700, Josh Poimboeuf wrote: > > > Syscall hardening (converting the syscall indirect branch to a series of > > > direct branches) has shown some performance regressions: > > > > > > - Red Hat internal testing showed up to 12% slowdowns in database > > > benchmark testing on Sapphire Rapids when the DB was stressed with 80+ > > > users to cause contention. > > > > > > - The kernel test robot's will-it-scale benchmarks showed significant > > > regressions on Skylake with IBRS: > > > https://lkml.kernel.org/lkml/202404191333.178a0eed-yujie.liu@intel.com > > > > To clarify, we reported a +1.4% improvement (not regression) of > > will-it-scale futex4 benchmark on Skylake. Meanwhile we did observe some > > regressions by running other benchmarks on Ice Lake, such as: > > > > stress-ng.null.ops_per_sec -4.0% regression on Intel Xeon Gold 6346 (Ice Lake) > > unixbench.fsbuffer.throughput -1.4% regression on Intel Xeon Gold 6346 (Ice Lake) > > Thanks for clarifying that. I'm not sure what I was looking at. > > I also saw your email where Ice Lake showed a ~10% regression for > 1e3ad78334a6. Unfortunately my patch wouldn't help with that, as it's > designed to help with older systems (e.g., Skylake) and newer (e.g., > Sapphire Rapids) but not Ice/Cascade Lake. > > Whether 1e3ad78334a6 helps or hurts seems very workload-dependent. > > It would be especially interesting to see if my patch helps on the newer > systems which have the HW mitigation: Raptor Lake, Meteor Lake, Sapphire > Rapids, Emerald Rapids. > > For now, maybe I'll just table this patch until we have more data. FYI, we tested this patch on a Sapphire Rapids machine in our test infrastructure. There are both improvements and regressions across different benchmarks, which does show that the impact may be very workload-dependent. Intel Xeon Platinum 8480CTDX (Sapphire Rapids) with 512G Memory: +-----------------------+----------+---------------+------------------+ | | mainline | + this patch | (percent change) | +-----------------------+----------+---------------+------------------+ | will-it-scale.futex4 | 5015892 | 5118744 | +2.05% | +-----------------------+----------+---------------+------------------+ | will-it-scale.pread1 | 2720498 | 2721206 | +0.03% | +-----------------------+----------+---------------+------------------+ | will-it-scale.pwrite1 | 2143302 | 2164511 | +0.99% | +-----------------------+----------+---------------+------------------+ | will-it-scale.poll1 | 4046943 | 4095046 | +1.19% | +-----------------------+----------+---------------+------------------+ | stress-ng.null | 19400 | 18689 | -3.66% | +-----------------------+----------+---------------+------------------+ | unixbench.fsbuffer | 369494 | 364181 | -1.44% | +-----------------------+----------+---------------+------------------+ Thanks, Yujie