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Shenoy" , K Prateek Nayak Subject: [PATCH v4 8/9] sched/fair: Simplify the entry condition for update_idle_cpu_scan() Date: Thu, 12 Mar 2026 04:44:33 +0000 Message-ID: <20260312044434.1974-9-kprateek.nayak@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260312044434.1974-1-kprateek.nayak@amd.com> References: <20260312044434.1974-1-kprateek.nayak@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MWH0EPF000C6186:EE_|DS0PR12MB6560:EE_ X-MS-Office365-Filtering-Correlation-Id: acc8c5e9-ca0f-4cdd-6e39-08de7ff26c46 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|36860700016|82310400026|7416014|376014|22082099003|56012099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 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)(1800799024)(36860700016)(82310400026)(7416014)(376014)(22082099003)(56012099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: TVVbFnJ5Pqs99lp6gqdtxdKD4oUJXwNG5sGtRA91Wxd+yPrdzt5eyiEiz/eX694afSEloFSNoQqJT8Xhr/53gGTcVgShkItijYjC1ZAKaduBkQGNKc2ox9PURub8D5wlgJj9OWpEf+HMJbs6vhsk3J3tqgZV3jUXWUe8/fGWNweTW1Bm+buEfdiwVQl1KHyYh5H0yEizT10QKieGW/yY51cqcUuxlP5qnvl790kY6k8f8nJtcKN4npAbHQxtErVW2gDitQyD71BTvq+lOUzmj/ZG4cnT1nmfF93amY8683mb5yj2eKjIQk/DkQDODgPTOpfsMTJe4Fepf9zkVdGwB5NnukdgpDzZI9+AbSyS8qk9tD+2MnFA0Sgj8G+Wv5LOWUBp5SYnaDFCatqPLf73c8IJxO1Ln2aCiWjqk/7BgXsXroXXnWrYh5foZHM4bgf7 X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Mar 2026 04:47:10.7461 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: acc8c5e9-ca0f-4cdd-6e39-08de7ff26c46 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: MWH0EPF000C6186.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB6560 Content-Type: text/plain; charset="utf-8" Only the topmost SD_SHARE_LLC domain has the "sd->shared" assigned. Simply use "sd->shared" as an indicator for load balancing at the highest SD_SHARE_LLC domain in update_idle_cpu_scan() instead of relying on llc_size. Reviewed-by: Chen Yu Signed-off-by: K Prateek Nayak --- Changelog v3..v4: o Collected tags from Chenyu. (Thanks a ton!) --- kernel/sched/fair.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 28853c0abb83..d7e4de909a63 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -11234,6 +11234,7 @@ static void update_idle_cpu_scan(struct lb_env *env, unsigned long sum_util) { struct sched_domain_shared *sd_share; + struct sched_domain *sd =3D env->sd; int llc_weight, pct; u64 x, y, tmp; /* @@ -11247,11 +11248,7 @@ static void update_idle_cpu_scan(struct lb_env *en= v, if (!sched_feat(SIS_UTIL) || env->idle =3D=3D CPU_NEWLY_IDLE) return; =20 - llc_weight =3D per_cpu(sd_llc_size, env->dst_cpu); - if (env->sd->span_weight !=3D llc_weight) - return; - - sd_share =3D rcu_dereference_all(per_cpu(sd_llc_shared, env->dst_cpu)); + sd_share =3D sd->shared; if (!sd_share) return; =20 @@ -11285,10 +11282,11 @@ static void update_idle_cpu_scan(struct lb_env *e= nv, */ /* equation [3] */ x =3D sum_util; + llc_weight =3D sd->span_weight; do_div(x, llc_weight); =20 /* equation [4] */ - pct =3D env->sd->imbalance_pct; + pct =3D sd->imbalance_pct; tmp =3D x * x * pct * pct; do_div(tmp, 10000 * SCHED_CAPACITY_SCALE); tmp =3D min_t(long, tmp, SCHED_CAPACITY_SCALE); --=20 2.34.1