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Shenoy" To: Dave Hansen Cc: Peter Zijlstra , "Rafael J. Wysocki" , Patryk Wlazlyn , x86@kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, rafael.j.wysocki@intel.com, len.brown@intel.com, artem.bityutskiy@linux.intel.com, dave.hansen@linux.intel.com Subject: Re: [PATCH v3 2/3] x86/smp native_play_dead: Prefer cpuidle_play_dead() over mwait_play_dead() Message-ID: References: <20241108122909.763663-1-patryk.wlazlyn@linux.intel.com> <20241108122909.763663-3-patryk.wlazlyn@linux.intel.com> <20241112114743.GQ22801@noisy.programming.kicks-ass.net> <20241112145618.GR22801@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: PN3PR01CA0174.INDPRD01.PROD.OUTLOOK.COM (2603:1096:c01:de::15) To DS7PR12MB8252.namprd12.prod.outlook.com (2603:10b6:8:ee::7) 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: DS7PR12MB8252:EE_|CH2PR12MB4261:EE_ X-MS-Office365-Filtering-Correlation-Id: f1ba886d-a236-4c7a-244d-08dd046a1174 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|7416014|376014|1800799024; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?TF0FEHZQBP6/gwnII9YQVHqEmlqRGj/mHWMb8WuIRrBeE3SLXhO02lC6C5RJ?= =?us-ascii?Q?x/a1xBJiAMqurUBTA8OSEKfJdvXZ7mzSmS8glDUF1DLwn0u9THnjNNZ/ZKX5?= =?us-ascii?Q?1JUau6vVqWe14iJQvEomzcf8gvRd7NDKX58lHcXV9mlWoSgjzECSkEVlnyjf?= =?us-ascii?Q?4fAMRDu6K7WC9UCZEn68uVS8NniLgsnjOWvMdpsLYQSwzxEhzzUyYzRhCx/X?= =?us-ascii?Q?Kz5UL3cFl3Zu3uUSpxLOW83lGLmCHjs1l8FCqnOpUiDwacnqj7xj3XX6RerZ?= =?us-ascii?Q?2PFHkT/HWXq73vlL2OVyMPpfHLOhMgTb6yMlHwaxZmDx4d2q+ysfu0wsolUi?= =?us-ascii?Q?5Au6pnrDlJKAP9wu9akhUA4q0Uy50YYsFrpDiBK7BrY+2VpL4lFirQiqre0q?= =?us-ascii?Q?APARyc62UYMeJY6dnmFucN7yPrKZ7W1aO4bEHX+LqSXZfMLALH/nazw3gl40?= =?us-ascii?Q?TAjVt13vOFgXTdaNjFzzl7cZ2jwcBnJXE/F8nl7z+//TYJ5my6CtkJgE2suD?= =?us-ascii?Q?fqCS2gren05ISLdXG+M5tl7EuWzG/AuaIj1CE6qRAaarRNmTqkVD5zaPNarL?= =?us-ascii?Q?iT98SP42YOFLkkRikEeRgUz4yGD1xEqQYYwMw/j8eyRxXvPRDgU1iklN+gNG?= =?us-ascii?Q?dyDxCPX4RrMO52cUR1Is13P/z3tr2SVuY4lxJiFw5yyOY6Pxzs7V/8czCqsj?= =?us-ascii?Q?pFyt8JTbQY6Lh+6GCKGu6CjiNgayAViZ0rBYWjaLfdig5BKYoyNFohOxGHqw?= =?us-ascii?Q?d6ksclp5r7HVZSmDHHMx4/2g5KZcAs6UwCxoGZG8mrMoAQ6HEw68Orsi+Jkm?= =?us-ascii?Q?Ik1TfPHGAXn6KEruHYYGy8INaI9PGZ/mbAd4lc6UZ+s7ojiNy99JxBmSCzTm?= =?us-ascii?Q?MYHcfQAq18J3FMu9lynH8DTNWUOUYr+IYD9ZUxIuZzCBiRi0aty4NBALBy96?= =?us-ascii?Q?8lNmg4us5hf3q+3qpJO1dZpKRPleqDXnIMUaxf8p4QIZ+UYTsR1x6IAdU7Kk?= =?us-ascii?Q?YFaGIR59JxPdhMAZTpwfsY+G5/moUbtCJg8oEAHBTwd+NkSF0Mqm6KEoQpWX?= =?us-ascii?Q?eGOPiSYjJcP1C5GX+8mbEuqgvCxGYvBSAM9beUldbGZhoe6Zk8Jw32HXU17X?= =?us-ascii?Q?p9Q7iCnmkBv+v8Ijp9C5uKL8sPVBI3npT4egjnsnGlaeTBJUuhZcPjvAH2bO?= =?us-ascii?Q?xwYQfn6whA7n2lpJYTLmxi3h1zb+8rpc3xSQkvpM1IeTocCWBJ3kb0IDbRVs?= =?us-ascii?Q?ntnM0iebeHKpWuchDQJ0peE1vLTbgRsCtFwR61WXVw66F738vbI6gwaVCXmK?= =?us-ascii?Q?L0m/ddCY2at7R6EShrEwDPsZFBZ74OaIcJGdfcqKRBMw9R83gyqY+oJO7Fim?= =?us-ascii?Q?3rIZADSl8zYvVqvrO2KYR79hXnjmGxe6nVPyUuREp2/XcqL59//uIW+UtH8R?= =?us-ascii?Q?cVF4QPgargPO2bOYk/S+vlg0KT9dcoMnrmBi0vYjKwH47GHfobpBt8olqKFx?= =?us-ascii?Q?AyQNUYCFDgmtjqcgfEUq6rNEIP9l62oLzK2aEfckyOmHSdBkyJqsND7qRbnc?= =?us-ascii?Q?J0znciuG22cZ338waoYTuwz6uveth37rE8h+8X11?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: f1ba886d-a236-4c7a-244d-08dd046a1174 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB8252.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Nov 2024 05:06:16.5772 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 5g+oidGaX8UCjWsdABK0k/HHrZAjie+JS4zjexz4aplRrV8zdgBZMWMlHLOgOfoutACdoymaZz2knOrItkXsAA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH2PR12MB4261 Hello Dave, On Wed, Nov 13, 2024 at 08:14:08AM -0800, Dave Hansen wrote: > On 11/13/24 03:41, Gautham R. Shenoy wrote: > > + /* > > + * This is ugly. But AMD processors don't prefer MWAIT based > > + * C-states when processors are offlined. > > + */ > > + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || > > + boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) > > + return -ENODEV; > > Can we get an X86_FEATURE for this, please? Either a positive one: > > X86_FEATURE_MWAIT_OK_FOR_OFFLINE > > or a negative one: > > X86_FEATURE_MWAIT_BUSTED_FOR_OFFLINE > Sure. That makes sense. > ... with better names. > > Or even a helper. Because if you add this AMD||HYGON check, it'll be at > _least_ the second one of these for the same logical reason. Fair enough. Will add that. -- Thanks and Regards gautham.