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bh=Dau5aMYoYyrYMoNbnbOnOFHzLgx6TcxW11f0fPds/hY=; b=WUhECcStXXerJWt9GJpxSmvaTG0eu1dXrB0MpmBAylBWfOt6bLXNlC745+N+h9cF6X86bl8AgfYG4LyMLPXL5CxVG6AlEemwgnQWM1cNwrvkPf1god3CCYhzKAlQ/vijOvANpF5xDwhjExIz8kr+54RLD1SHrrUUP+ofl3t50kk= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=os.amperecomputing.com; Received: from PH0PR01MB7975.prod.exchangelabs.com (2603:10b6:510:26d::15) by CH7PR01MB8977.prod.exchangelabs.com (2603:10b6:610:24f::16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9366.13; Thu, 27 Nov 2025 09:17:01 +0000 Received: from PH0PR01MB7975.prod.exchangelabs.com ([fe80::6926:a627:118e:8050]) by PH0PR01MB7975.prod.exchangelabs.com ([fe80::6926:a627:118e:8050%4]) with mapi id 15.20.9366.012; Thu, 27 Nov 2025 09:17:01 +0000 From: Huang Shijie To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org Cc: patches@amperecomputing.com, cl@linux.com, Shubhang@os.amperecomputing.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, linux-kernel@vger.kernel.org, vschneid@redhat.com, vineethr@linux.ibm.com, kprateek.nayak@amd.com, Huang Shijie Subject: [PATCH v3 2/2] sched: update the rq->avg_idle when a task is moved to an idle CPU Date: Thu, 27 Nov 2025 17:14:50 +0800 Message-Id: <20251127091450.250797-3-shijie@os.amperecomputing.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20251127091450.250797-1-shijie@os.amperecomputing.com> References: <20251127091450.250797-1-shijie@os.amperecomputing.com> Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: SG2PR02CA0052.apcprd02.prod.outlook.com (2603:1096:4:54::16) To PH0PR01MB7975.prod.exchangelabs.com (2603:10b6:510:26d::15) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH0PR01MB7975:EE_|CH7PR01MB8977:EE_ X-MS-Office365-Filtering-Correlation-Id: d5c3d164-4d0c-4a11-1f40-08de2d95b92d X-MS-Exchange-AtpMessageProperties: SA X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|376014|52116014|7416014|1800799024|38350700014; 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charset="utf-8" In the newidle balance, the rq->idle_stamp may set to a non-zero value if it cannot pull any task. In the wakeup, it will detect the rq->idle_stamp, and updates the rq->avg_idle, then ends the CPU idle status by setting rq->idle_stamp to zero. Besides the wakeup, current code does not end the CPU idle status when a task is moved to the idle CPU, such as fork/clone, execve, or other cases. This patch introduces a helper: update_rq_avg_idle(). And uses it in enqueue_task(), so it will update the rq->avg_idle when a task is moved to an idle CPU at: -- wakeup -- fork/clone -- execve -- idle balance -- delayed dequeue task -- other cases Signed-off-by: Huang Shijie --- kernel/sched/core.c | 36 ++++++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 12 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0c4ff93eeb78..8531ef68ce76 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2078,8 +2078,25 @@ unsigned long get_wchan(struct task_struct *p) return ip; } =20 +static void update_rq_avg_idle(struct rq *rq) +{ + if (rq->idle_stamp) { + u64 delta =3D rq_clock(rq) - rq->idle_stamp; + u64 max =3D 2*rq->max_idle_balance_cost; + + update_avg(&rq->avg_idle, delta); + + if (rq->avg_idle > max) + rq->avg_idle =3D max; + + rq->idle_stamp =3D 0; + } +} + void enqueue_task(struct rq *rq, struct task_struct *p, int flags) { + int delayed =3D p->se.sched_delayed; + if (!(flags & ENQUEUE_NOCLOCK)) update_rq_clock(rq); =20 @@ -2100,6 +2117,13 @@ void enqueue_task(struct rq *rq, struct task_struct = *p, int flags) =20 if (sched_core_enabled(rq)) sched_core_enqueue(rq, p); + + if (delayed) { + if (entity_eligible(cfs_rq_of(&p->se), &p->se)) + update_rq_avg_idle(rq); + } else { + update_rq_avg_idle(rq); + } } =20 /* @@ -3645,18 +3669,6 @@ ttwu_do_activate(struct rq *rq, struct task_struct *= p, int wake_flags, p->sched_class->task_woken(rq, p); rq_repin_lock(rq, rf); } - - if (rq->idle_stamp) { - u64 delta =3D rq_clock(rq) - rq->idle_stamp; - u64 max =3D 2*rq->max_idle_balance_cost; - - update_avg(&rq->avg_idle, delta); - - if (rq->avg_idle > max) - rq->avg_idle =3D max; - - rq->idle_stamp =3D 0; - } } =20 /* --=20 2.40.1