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Sun, 11 Oct 2026 22:34:56 -0500 Message-ID: <7c4dbf1d-ba28-484d-b7e1-a713414c284d@amd.com> Date: Mon, 12 Oct 2026 09:04:55 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] sched/cache: Avoid publishing partial LLC utilization To: Jemmy Wong , Ingo Molnar , "Peter Zijlstra" , Tim Chen CC: Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , "Mel Gorman" , Valentin Schneider , References: <20261010113425.34829-1-jemmywong512@gmail.com> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20261010113425.34829-1-jemmywong512@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MWH0EPF000C6192:EE_|PH7PR12MB7938:EE_ X-MS-Office365-Filtering-Correlation-Id: 1580257a-21c7-4243-63cc-08df2811cee5 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|7416014|36860700016|82310400026|23010399003|11063799006|56012099006|10067099003|22082099003|18002099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: Fzs1Y3VVRUVOFm22LPpmYKxGinHJ8RqNACblCRyBCRevAFfzaIjj4sRkZUhBEcSphE3SxTN4wuOZ7Dw19zRDzfbKXvZ5VUbcCmY29X7NjaCafaAnFypVZTe5giXQO5ALk+T7dEUrs9hM3/TSgTn0s0KnFhHkzKd2tshJZIOv9IycEwCpO8TKJNaYL29Bw/+DaT/odpiUJ7wep+2v7rg6lrIDy+NN1CIZHEvicGb+qSh3+9CQwr8UqpWy1NYXBWFdS3Z3J6Bajcz4yFma3v/PsFLc7RFnCQBU+UnqrZOzImZtfF39qlZFtftmdo+1eGhSiPkTfEnrszLjWdAzqZ9fhOt2i8KvrQcRyvIr679qcB0TxyBBtL7N6IJVDGuhXr21UrLIC/KYyf1qO+6MwEF6VjHb612TcFck7oCzgBr42S1PnNssB6SXgbWAkZJ/0Ly0 X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Oct 2026 03:35:05.9780 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 1580257a-21c7-4243-63cc-08df2811cee5 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: MWH0EPF000C6192.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB7938 Hello Jemmy, On 10/10/2026 5:04 PM, Jemmy Wong wrote: > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -12121,6 +12121,13 @@ static void record_sg_llc_stats(struct lb_env *env, > if (env->sd->child != rcu_dereference_all(per_cpu(sd_llc, env->dst_cpu))) > return; > > + /* > + * Affinity retries can remove CPUs from env->cpus. Do not publish > + * partial utilization against the capacity of the whole group. > + */ > + if (!cpumask_subset(sched_group_span(group), env->cpus)) > + return; > + nit. When sched_balance_rq() does a "redo" and arrives here, env->flags will always have LBF_ALL_PINNED set. That would be a much cheaper check compared to cpumask_subset() to ensure env->cpus covers all CPUs. Thoughts? > /* > * At this point we know this group spans a LLC domain. > * Record the statistic of this group in its corresponding > -- > 2.25.1 -- Thanks and Regards, Prateek