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Mon, 19 Jan 2026 20:26:24 -0800 Received: from [10.136.37.139] (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Mon, 19 Jan 2026 20:26:13 -0800 Message-ID: Date: Tue, 20 Jan 2026 09:56:12 +0530 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 01/15] sched/idle: Handle offlining first in idle loop To: Frederic Weisbecker , Peter Zijlstra CC: LKML , "Christophe Leroy (CS GROUP)" , "Rafael J. Wysocki" , "Alexander Gordeev" , Anna-Maria Behnsen , Ben Segall , Boqun Feng , Christian Borntraeger , Dietmar Eggemann , Heiko Carstens , Ingo Molnar , Jan Kiszka , Joel Fernandes , Juri Lelli , Kieran Bingham , "Madhavan Srinivasan" , Mel Gorman , "Michael Ellerman" , Neeraj Upadhyay , Nicholas Piggin , "Paul E . McKenney" , Steven Rostedt , Sven Schnelle , Thomas Gleixner , Uladzislau Rezki , Valentin Schneider , Vasily Gorbik , Vincent Guittot , "Viresh Kumar" , Xin Zhao , , , References: <20260116145208.87445-1-frederic@kernel.org> <20260116145208.87445-2-frederic@kernel.org> <20260119125347.GT830755@noisy.programming.kicks-ass.net> Content-Language: en-US From: K Prateek Nayak In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL6PEPF0001AB4C:EE_|PH7PR12MB5781:EE_ X-MS-Office365-Filtering-Correlation-Id: 111d7472-34ce-4c05-5add-08de57dc1269 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|1800799024|36860700013|7416014|376014; X-Microsoft-Antispam-Message-Info: =?utf-8?B?TUFnT0l5YlNJU3FxQ0wvQjc5WmNUcUgxZjF4NVdqbmgvM2J5MFNCQ01jMlZh?= =?utf-8?B?Z1hOOUFhNEpMc2owUk5RN1dtaXUvbzBGOXBlOTlnWDR4bXlUZERUaGNuQmho?= =?utf-8?B?M2FITTZTUE5LTnZ2MzZwaFYveHB6czZnN2RwZDNxcnJYMnNmK1pjL2tDaVl4?= =?utf-8?B?eW9tWFU4WE5FcC8zSERIcDJnY21pWURIZ0VsMFdLMmlicDJrUjVVQmtjSXM0?= =?utf-8?B?eFRGRW5zaFpGT1d5bXdTU2J5VUw1Zm81S0MyTDZkTElxV3FXdU44d0RUdmJa?= =?utf-8?B?ZzV3S3lvclZQRDVoc0NDdi9oZitmOG4wVE8yUmpZQzREMjZpOE9UeVU1REtE?= =?utf-8?B?U3RYRHA2Z2JIRHVNR2RkUXpOWDhpd0pMQ3lzNzVqTEI5YkpnR0J0UzZvTGtu?= =?utf-8?B?SUxacWpGL2tCa2Q5bXVUbnMrc0dTcEpnbm1lZm1HNXRUdTNtRHZZMjQ3UzBV?= =?utf-8?B?YS9YZGtHMjc2MDFIYmJDK2hNVERuc29Ed2dXWWRqWE5Bek44UXhvcjJPbjda?= =?utf-8?B?bUlZMTU0eXgxUFRrTElyMm5JbUIyTWJ1dTFoTWQ1TForMDdPYW00RHpOT0Jm?= =?utf-8?B?bUlxU3psdFY3WXl2RG0vR2Fnd0Z2TnVqeE9kQzBXMytSNVl4Zzg1Y0dtbnJk?= =?utf-8?B?M05JQ0dyc3hTTE1qVkV2TzlncU55clYvVnEyTkY3Tzg0eUNKK1VaYTZqMlIx?= =?utf-8?B?Q3ZLUG1lVFBYLzlFYzdIeU5QL0ZsNjNnS3Z5ZmVZUVdXMlZPb3JUcmd1cHlT?= =?utf-8?B?UmRCQUdxa1RRZ01CZlNXanB3UlB3VlRnZ2VvaWJTWEVveEV4YzJ5WTU0Ynp1?= =?utf-8?B?R1ppZFY4cWRtTTRXa0x0elB6aFhybWNjb3R5RHBvTnQ0c2FRQ2tURkMyNkdO?= =?utf-8?B?RllZdDh1cUZSWjgwd0x6aStlTUVtbjIwbUNrdWpqZkNoQ2p0MG1VdU9renhx?= =?utf-8?B?bnlaRW44VkpQQWdHVnJCN29tckpLYlpXRGpadFloa3BuVEVSeFBiQWpOMmt2?= =?utf-8?B?L2dJZkJsQ1hhOXJRN1FBVEIrbjRteFdRMW9BMEM0RnpDT1YxQTQ1eFpLMWJv?= =?utf-8?B?Vlg5S2t3SjJVWG5mT29SVXJ2dncyY2QwNWdWaTJsanlLUXRHSE81Znl6SlJl?= =?utf-8?B?UlBvYmxPcEE1cTVSQ1VJSTdKU3dPN3lpUmU1NFM4M0t2VDBLSVpXcjRPNk8y?= =?utf-8?B?Qzg4S01pSlpSWkw3UE13MnV0bkV4UndnK3pmK21IRVhWNzQ3QlF3NGwxeHVl?= =?utf-8?B?RldFd3pMa1JBd2ZmQUZDOHZZMDQwZWEyZmhCTVozcmxwYnp6c0k0cnM4Q0hR?= =?utf-8?B?VDRCeGVST0JReU1FNTNER0F4WitPTEdjVkg5dFE1SWZ3bXl2ZDNhU25YNVpq?= =?utf-8?B?VmhhQnBKblN5YWRFWlIwaHdoOE0vVXpiTCtPZmVZZHVhelMwRXpiN0dySkg5?= =?utf-8?B?eWJRTWIxRmk3TmNMSllsWlpkdXlmTE9FQXdoUm1TNzFnajR5T0d3OE44U1VR?= =?utf-8?B?YUZibTR0K3NzNWVYblBSMlZQMDIzWUJnUTZ0QnVkb2F1eE9zblJrVEMvb29M?= =?utf-8?B?clN5dGdGNmNuT3k1N1BEd1Zmc1VBMThmQXgySXpacU1UR1huV2pCMjlxdFJU?= =?utf-8?B?dTdIMmtjV05JSGI0OU11b2JrQ1RSby9WNzJHZlFXOEc3Z09DOE1Rdmdkb1du?= =?utf-8?B?a1dpSll4SlkyQW51VVNpOVc0aVYzUkM4Qk5LSi9JY002ZkZ2WWU5b2FOcFNv?= =?utf-8?B?QmpoUURoaXEzMzAzQnI3RXVyd0xsNHZQYk9JSjhkWmQwT01lQkJHSHc1aXFh?= =?utf-8?B?dnFRRXQySlhNV21sWllydHczclp6YVVrKzNWSVhXYzY2K3ZzcjRlYStSK2dB?= =?utf-8?B?TWxCQ0R5dng0ekhWOWZIclA0OFd6cUNUNm5wNm93SXNNZTdXUDJ0MWU2SGZr?= =?utf-8?B?c1EyaUticlBIbzNVdnRENGplalArZ283M1RyWDlFZS83cEQyeHhoMU9CVkhn?= =?utf-8?B?WnpzaDJiY05sRUtnbEtsYitKVmNOWjFGdllUR1dIS0xVZjNsdWhUQzZkMVYr?= =?utf-8?B?Z2tCUnVSRFpmRW8xUXA3VkxWRGNZbnJxR05heml2aW9FYkJZRVZFeEtURGpK?= =?utf-8?B?M0JPakpReWJDNGxPR3oxbFhpR1Z4cGM2eHk5TVRHUnU0cWNLbFhKQUxTTnM5?= =?utf-8?B?OFAzTVA2elQwUGZMdHFLcm1GVmhSR0RvVWRSdXdYbjJ3MjZicGhtajM3SVh6?= =?utf-8?B?Q3hXYU1EMjBZaWdOWjRvMHpab2tRPT0=?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(82310400026)(1800799024)(36860700013)(7416014)(376014);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Jan 2026 04:26:24.6078 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 111d7472-34ce-4c05-5add-08de57dc1269 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BL6PEPF0001AB4C.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB5781 Hello Frederic, Peter, On 1/20/2026 2:34 AM, Frederic Weisbecker wrote: > Le Mon, Jan 19, 2026 at 01:53:47PM +0100, Peter Zijlstra a écrit : >> On Fri, Jan 16, 2026 at 03:51:54PM +0100, Frederic Weisbecker wrote: >> >>> kernel/sched/idle.c | 11 ++++++----- >>> 1 file changed, 6 insertions(+), 5 deletions(-) >>> >>> diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c >>> index c174afe1dd17..35d79af3286d 100644 >>> --- a/kernel/sched/idle.c >>> +++ b/kernel/sched/idle.c >>> @@ -260,6 +260,12 @@ static void do_idle(void) >>> { >>> int cpu = smp_processor_id(); >>> >>> + if (cpu_is_offline(cpu)) { >> >> Does it make sense to make that: if (unlikely(cpu_is_offline(cpu))) ? > > Yes indeed! nit. but don't we inherit it from: #define cpu_is_offline(cpu) unlikely(!cpu_online(cpu)) so it will end up being annotated with unlikely() no? -- Thanks and Regards, Prateek