linux-kernel - [PATCH v3 0/2] sched: update the rq->avg_idle when a task is moved to an idle CPU

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Message-Id: <20251127091450.250797-1-shijie@os.amperecomputing.com>
Date: Thu, 27 Nov 2025 17:14:48 +0800
From: Huang Shijie <shijie@...amperecomputing.com>
To: mingo@...hat.com,
	peterz@...radead.org,
	juri.lelli@...hat.com,
	vincent.guittot@...aro.org
Cc: patches@...erecomputing.com,
	cl@...ux.com,
	Shubhang@...amperecomputing.com,
	dietmar.eggemann@....com,
	rostedt@...dmis.org,
	bsegall@...gle.com,
	mgorman@...e.de,
	linux-kernel@...r.kernel.org,
	vschneid@...hat.com,
	vineethr@...ux.ibm.com,
	kprateek.nayak@....com,
	Huang Shijie <shijie@...amperecomputing.com>
Subject: [PATCH v3 0/2] sched: update the rq->avg_idle when a task is moved to an idle CPU

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 set tries to resolve it.

v2--> v3:
  -- merge patch 3 into patch 2:
      move update_rq_avg_idle() to enqueue_task().

   v2: https://lkml.org/lkml/2025/11/27/214   

v1--> v2:
  -- Put update_rq_avg_idle() to activate_task()
  -- Add Delay-dequeue task check.	

   v1: https://lkml.org/lkml/2025/11/24/97


Huang Shijie (2):
  sched/fair: set rq->idle_stamp at the end of the sched_balance_newidle
  sched: update the rq->avg_idle when a task is moved to an idle CPU

 kernel/sched/core.c | 36 ++++++++++++++++++++++++------------
 kernel/sched/fair.c | 12 ++++++++----
 2 files changed, 32 insertions(+), 16 deletions(-)

-- 
2.40.1