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Shenoy" , Swapnil Sapkal , Ingo Molnar , Juri Lelli , "Vincent Guittot" , Anna-Maria Behnsen , Frederic Weisbecker , Thomas Gleixner , References: <20250904041516.3046-1-kprateek.nayak@amd.com> <20250904041516.3046-2-kprateek.nayak@amd.com> <98aa5e37-258e-4efe-8e09-b8cfc5f78f0d@linux.ibm.com> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <98aa5e37-258e-4efe-8e09-b8cfc5f78f0d@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL6PEPF00022573:EE_|DS7PR12MB8252:EE_ X-MS-Office365-Filtering-Correlation-Id: 425bfeca-1329-42bc-c08a-08ddfbd8e14e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|36860700013|1800799024|82310400026; X-Microsoft-Antispam-Message-Info: =?utf-8?B?b2tvL2JZWDByNFhzWk9YWWNSUVBSeHhIMEtQb0pBTHRLNTFJdW5YeWtocE9N?= =?utf-8?B?M2lBZk1uRTJnRWJKUkhNckxxMGJCNzM1b05qazAzK1Z0T0dPRWc5WXcvQit1?= =?utf-8?B?djhCdEFUUHdtSGFPeWwvNEV3ODNtUEpjK0c1YnNBVjdFMHhsS0w4T3FvNVRI?= =?utf-8?B?MGZQbFU1cWo3dmsyVWxBMzlCeFU3WkJiSHlEV1libTdLL1pEbDg5S0c1bUNZ?= =?utf-8?B?YWRNc05Gb2dGQkJVdldUWXNBdm85RjhZM3pNcjE4SHBxTTQzeDJnK2t3QUZn?= =?utf-8?B?bTZpVDNxaHBTVjFUMmI3LzhNVUl4ckZVRlh5R09UV2MrSllla3pYcUZzV1Vj?= =?utf-8?B?dUZPRVRHazZXM2dkZWFSaWpsb05Ha0ZQUFpIR2NpU2NKN0NVTERIS3g2aE5y?= =?utf-8?B?ZFJialoxL2pSeEptRzc1NXRyZFNqUklBL1Bid014WlBlaWNtUFBsUWRDU0FS?= =?utf-8?B?ZGVGYS8zTGZQWkJYMnpNWnVDOFpDUkQ4SnFEbTBTVExhOFlzc1NOdmo1KzRL?= =?utf-8?B?cGsrd2E3MlpIeklUR0FhQzdhMnQyNWt6RXVYUElWTEdmMHdhWDgvVmpKbG9a?= =?utf-8?B?Z3hWWUYzdjlwWHdKeGo5bE9oYktQNlh6ODEvK1FzaTI0ZmVuZGFhMnAvVFBs?= =?utf-8?B?eWJkZENBQnVHMXJOYTlpZ1VHTE1lUXZaRDl1SnEwT2tZbFZGeWhWbzNGV0F2?= =?utf-8?B?S0VhWVpLZkR3YzYxWnB2RFg5bm5INWMrV2RIMmtVQ2k3cTFlRHlramhzT3Vk?= =?utf-8?B?dE1XOTgwU2hqdGwveHU5Sm1PSnhFOGV3dkpxZ2QyV2dLdk5PNFBRVExwY1FR?= =?utf-8?B?T1F2czBSb2dZSGd5NFBjRDU2VDcyQ2xaLzRFSGJpNkl4QjViMDJ4dGVrTXBs?= =?utf-8?B?cVhYVldGdDZ0MEM0b2R5YVUxcmF1T042ditoVm9wS243T0pHV1JqdU1uR0ND?= =?utf-8?B?QjlUZWRDN09ReHMxcVFoRmlaOTFUcEtpTWZqc21SNnV4aVJrT1FGNzRBOUph?= =?utf-8?B?MFhhbnBUR1pGZmxKdzZHMTdDbEFjNW5PLzJBVldEcUVHTWExTzluT0VoZVFw?= =?utf-8?B?SkRlTThOS3BwVmo5SzYvc2daeXo5YWpORW80MjJHeFBBbDlqNVhFVUZHaWZ4?= =?utf-8?B?L2h5bDZXV0pMdkpDbTVhYnRDVlJ6UEcrZHphOWFqc2VhSEpDb3ZCamIySDRp?= =?utf-8?B?cDk4RGVXZFd4VjAwNCtaNU52bzZjcFRVMmkwN0h5NGZHUTNad2tEQ290WlhK?= =?utf-8?B?akJud2pEOEVpcnozRk15WCtST2NBdXQyUytsdDR1SEFkelVQNGkyNzNWR3B0?= =?utf-8?B?eGhUZGRKSzA1UUlIbjl2UkFGdHErUUw5Y0hVR0dpVExPRUVjeGZUNXFXNk5v?= =?utf-8?B?dC9uejZqSTlVdGtVdjVYclE0U1dGYzhzVUR4VlM4ZHpkeVI2TGliZzhMUWgw?= =?utf-8?B?ZHFqQnpzWmVTK3BVR2dwWXBTRmxCaTg5RlN0alJrcGZQa1FNODdEazZpa0xt?= =?utf-8?B?Z3QrejBUYWFFWGhwQW9ROFozRUpCWFVBbnhHV3JwZkg2aXBRS0ovRmZVNnhO?= =?utf-8?B?bFgzc1QvdlpXVUM0bFRJd0FyZWRVRDdaYXlreVdyQU1DQ0NxbllPSlJoVzU0?= =?utf-8?B?d0xyMUlLM3NhZjdFYVZmQmdVc3lxRTY5U0pBR0ovWkpWQVF1eFZTTVpyS21i?= =?utf-8?B?bEFFb01BV3NRSXNLdzJQWjFEN05hcFFwTFFZYkMvbk9yN3dRczhvUmRaZHJ5?= =?utf-8?B?NmFVOElDY1RLRVc4WDhuc2dPTnBlMkZlRDNFL0R4ZW5xWkgzRUxTWU1oM0ov?= =?utf-8?B?UnlRdXZ1T3ZKTnRLOHBTT3E0aURUYm0vUmkyTzRLYmEyQTFFYUlUN1ZJaDhq?= =?utf-8?B?N1JnUGVzUTdvRVB4WlltbERPL2wvWkxabng0L1hHaE1QVzIxY0kwZmt0aDRl?= =?utf-8?B?OXhhUmNJbEdUZHRoSHNQTURQUm9GWDlZZmt3RFQ5RzRRNDhwNzZWR2Y0RW9y?= =?utf-8?B?MmVhR1JmVXVPQzBhQURxeWhvZWtMT1RUdGowNG5QZDVJMmY5TTcyZk5Va1Jl?= =?utf-8?Q?6xUaww?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:satlexmb08.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(376014)(7416014)(36860700013)(1800799024)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Sep 2025 02:11:46.7592 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 425bfeca-1329-42bc-c08a-08ddfbd8e14e 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=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BL6PEPF00022573.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB8252 Hello Shrikanth, Thank you for the review. On 9/25/2025 1:56 AM, Shrikanth Hegde wrote: > we have both sd_llc->shared and sd_llc_shared usage spread > across the code, is it possible to remove sd_llc_shared and use sd_llc->shared > instead? > > Likely sd_llc is cache hot and access to shared should be fast too. > In turn this could free up some per cpu area. Ack! That can be done. Probably the motivation was to avoid an additional dereference in the scheduler hot-path but apart from {set,test}_idle_cores(), most other usage is either in the slow-path, or we readily have access to "sd_llc" already so dereferencing "sd_llc->shared" shouldn't be any more expensive. /me goes and looks at usage of {set,test}_idle_cores() So set_idle_cores(), I would consider, is still in the slow path since the CPU is going idle and out of all calls to test_idle_cores(), only numa_idle_core() doesn't access "sd_llc" prior to test_idle_core() but given it is in a for_each_cpu() loop, I think we can make some optimizations there to reduce the amount of dereferencing. > > Any thoughts? I think it makes sense. I can send out a separate series with Patch 1,2 and this cleanup on its own discussion the optimization for the "nohz.idle_cpus_mask" in a separate series. -- Thanks and Regards, Prateek