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Shenoy" CC: Chen Yu , Vincent Guittot , Juri Lelli , "Dietmar Eggemann" , Steven Rostedt , Ben Segall , Mel Gorman , "Valentin Schneider" , Madadi Vineeth Reddy , Hillf Danton , Shrikanth Hegde , Jianyong Wu , Yangyu Chen , Tingyin Duan , Vern Hao , Len Brown , Aubrey Li , Zhao Liu , Chen Yu , Libo Chen , Adam Li , Tim Chen , References: Content-Language: en-US From: K Prateek Nayak In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL02EPF0002992D:EE_|DM4PR12MB6088:EE_ X-MS-Office365-Filtering-Correlation-Id: 237d7fc0-1dd2-4b8a-dce2-08de151b991f X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|32650700017|1800799024|36860700013|82310400026|7416014|376014; X-Microsoft-Antispam-Message-Info: =?utf-8?B?K1RXaldvWTJ2L05jbUpXcXpjS096bjJSZGkvcTNVU3liWmxqamdRcVNlcUdN?= =?utf-8?B?Zjc0VGs3R2FNRFdXY3Ird3ArNTdkWFk5ZUZERFIrZDNsRlhKQXhRd1dJdVg1?= =?utf-8?B?S1dGTDFxVm5jdlFaMzdoSGZ6aEt0S2RXV1dFSG1zQU83akFXQWpRMzRaM0V0?= =?utf-8?B?VEFEdkpSUnF2MFBycTNmMHRmMFViaUJNbXBLdXZPWG5JU2N6VDZoa1pIS1lx?= =?utf-8?B?OHYyb25sWWVONDNHeE1IeUJhWENEeXFVSnZ3a0QzYitmQ3JadWJaZ0pVL1VW?= =?utf-8?B?N2xleFZQUzhhL2tEZGE2QjZQenR4TlUxLzRET1AzSTVqc1JTSVgwaXVPdmFQ?= =?utf-8?B?OXJLeU03SVhNaVlwbmM5OE1tWHpYZWM5SmxIbS9MQjVBRHJNWWNJbDBOT2tN?= =?utf-8?B?RXk1V1k2cEVNR0JKcDhLNDhFcCtrOXJaZm8zZC9kajIzcDFIYXVpTk1LSENS?= =?utf-8?B?eU5iMkxlNFAzdmJ4VGdVN2xPam8yOWJiTmd0ME5QUkUzbWRDcnBVRE9TdjV0?= =?utf-8?B?T0lDemdNTjBPb1o3T2NQcTdlUTUvTy9tMnVXUmZLamJGNXIreW1vNVliRHl3?= =?utf-8?B?cWlxSlNWZXhRZmJmekFtaHdUa2NzWFUxcWpBWHRwb2pSTXBuTFhaUDBrenRj?= =?utf-8?B?ZzdTejMxSVAvVlRwd1ZudUlXcE5aU2dpSDd3TjR6RGxTTWloYXJpZC9lYnhn?= =?utf-8?B?UVlKY1Z3eGxWZG1xZUdKTGFQOHMrcW9jSkhNYVN3U1pFVTlEcFRDcUw3aEdX?= =?utf-8?B?OU5ZU2tyNms3R2ZJUjlYU1UwNTRTby9hYjAxbytWdnJlbGNEYitRK2NRT1ZR?= =?utf-8?B?TmZIRjl0TW1RRURhdkFIQjBKRkZMeUVvVHExZ0gxNXhPRGE0N1JxU0dqZUh4?= =?utf-8?B?MUZTNnpndjcxN1B3T2ViY3NJQ203RW9ZUFFMcUNnbm1EOEpmMGJiVjc1ejIx?= =?utf-8?B?S2NvRkphOW55WHdEMnlhZllXQkdUWUVoSEJMd2VIangzYmJxM1hhdDd3VS9w?= =?utf-8?B?K1pkWmlVQktVWkpvWjRJNFFVTjFYbU5XM0VudWVtL2tZVUpiN1E3ZlRCMzFP?= =?utf-8?B?QW45S2RxK2hzUG9oNDRqKy9BMWRDbWh6Tko5OVJOZ2VwSmE5N3dKZ2VCNFJK?= =?utf-8?B?eitzOVRJV2ZTQkhVbHpzWDRkSGQvZG92QVcrRXV2TWtHYlJsNGx6cDJ2UnRp?= =?utf-8?B?ZU5aUTIyOEZPZG1uUndTR1FzQ251dFhTd1RVSEQyY3FHUXBNb1F3TTEwU3hD?= =?utf-8?B?TkdXQmc3d05Qc01IdUtmZUZnYjdEOVBDRXBwQkRCNHRDb2dTTmdpUHpoUHNL?= =?utf-8?B?WGxZOFZ6Umh3QXp6OERDMEFKSWdIQ2RnRzRNRU0wcXJMczNxeHZXYTc4OUJn?= =?utf-8?B?UmhNYm83M2lMVkp0OVJVeVZWUjNCUHF0MGRsR0kzRjFHVUNTTWordzlYbWgv?= =?utf-8?B?cWpYeWVDa1JSeExDTTdabTl6RGpDRWpvT01EWHJRei83QjhSckgxd2VTbGxN?= =?utf-8?B?Zy9FYXhnd2lVdE5TOXFrdWdZMUc2R2lqaFNYN3RUZloyd1YrR1RETThtTWEz?= =?utf-8?B?VEE2MHdwZnhZNU5pVTRzbHFUdlQxazNQSzRzNTJINEVWaHk2Y29udVM1aVdn?= =?utf-8?B?VGVwOW9Sa1BjYVRQQ1ZyL3ZRZnU1em1OL0YyME1MQWFrT1RuWXlqVS9JV2pQ?= =?utf-8?B?QTBEQ0lNbmJpWmFFMnVlUUtjdmtnZU1tci80MFRLbUt6cUJUSzhkRWo5ampv?= =?utf-8?B?MHUveXdRNjRtWnFoVi9CdTMrM2RKVS9XQ05WTGQ3OC9OOEJOR25EaWpNRE1U?= =?utf-8?B?VStXZnR6QzVYRkRNM2N0NlFxaHkwMFpqd0NSajNlVUlnTnErK2o5YVhwMExm?= =?utf-8?B?djhGOEZONEdUeGl2VzVRcnVSOFI1bTBoZnAwTGJMSGpUQkJZRmV5eUxkNFRM?= =?utf-8?B?MmRPamN3ZVZxeitCY1VEUkJUTmF5Q3BiZ0FpRmhKeHh6N0dwRWprdUlCbVVO?= =?utf-8?B?YmJmZlA0d3ljSkYxQlJJU0VmVUZObUpEZGF6N1Y3c1p4MDlON0NWTURTUE1U?= =?utf-8?B?ZlQ0SzJyWGxub2MvdUFOTURvSHREYlJoeXQwa0ZMWWNPdDJBTFJLa3AwN3JT?= =?utf-8?Q?CsBw=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(32650700017)(1800799024)(36860700013)(82310400026)(7416014)(376014);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 Oct 2025 05:42:21.0203 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 237d7fc0-1dd2-4b8a-dce2-08de151b991f 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: BL02EPF0002992D.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB6088 Hello Tim, On 10/11/2025 11:54 PM, Tim Chen wrote: > @@ -2530,10 +2531,12 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att > * between LLCs and memory channels. > */ > nr_llcs = sd->span_weight / child->span_weight; > - if (nr_llcs == 1) > + if (nr_llcs == 1) { > imb = sd->span_weight >> 3; > - else > + } else { > imb = nr_llcs; > + has_multi_llcs = true; One caution: this will not hold if all the CPUs aren't online during boot. One case I can think of is when the kernel is booted with "maxcpus" cmdline and CPUs are hotplugged later. Unfortunately, I don't think we even have the raw topology data from the arch/ side under such scenario to accurately make a call if the system contains single or multiple LLC :( I'm not sure if it is feasible but assuming the task_work() cannot run if &sched_cache_allowed is false, can the fist instance of the task work for sched_cache do the necessary setup? > + } > imb = max(1U, imb); > sd->imb_numa_nr = imb; > > @@ -2581,6 +2584,13 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att > if (has_cluster) > static_branch_inc_cpuslocked(&sched_cluster_active); > > +#ifdef CONFIG_SCHED_CACHE > + if (has_multi_llcs) { > + static_branch_enable_cpuslocked(&sched_cache_allowed); > + pr_info("Cache aware load balance enabled.\n"); > + } > +#endif > + > if (rq && sched_debug_verbose) > pr_info("root domain span: %*pbl\n", cpumask_pr_args(cpu_map)); > -- Thanks and Regards, Prateek