Re: [PATCH v6 2/2] sched: update the rq->avg_idle when a task is moved to an idle CPU

[Shijie Huang <shijie@amperemail.onmicrosoft.com>]

On 16/12/2025 15:17, Vincent Guittot wrote:
> On Tue, 16 Dec 2025 at 07:22, Shijie Huang
> <shijie@amperemail.onmicrosoft.com> wrote:
>>
>> On 13/12/2025 09:36, Vincent Guittot wrote:
>>> put_prev_task_idle() would be a better place to call
>>> update_rq_avg_idle() because this is when we leave idle.
>> The update_rq_avg_idle() is not only called by current CPU, but also
>> called by
>>
>> other CPUs. For example, the try_to_wake_up(), update_rq_avg_idle() is
>> called by
>>
>> the other CPUs. So enqueue_task() is a good place.
> But put_prev_task_idle() is called by local CPU whenever it leaves
> idle so instead of trying to catch all places that could make the CPU
> leave idle it's better to use this single place.
> And as you mentioned, put_prev_task_idle is only called by local CPU
> whereas enqueue_task can be called by all CPUs creating useless
> pressure in the variable.

The rq->idle_stamp is set at sched_balance_newidle().  then we call 
update_rq_avg_idle()

in put_prev_task_idle() right now. How can we update the rq->avg_idle?

Thanks

Huang Shijie

>>