Re: [PATCH] sched/stats: Fix run_delay over-count for proxy-migrated blocked donors

[K Prateek Nayak]

On 10/27/2026 5:43 PM, Kayra Cizmeci wrote:
>>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>>> index 04b62c16fa8c..d5758b78b741 100644
>>> --- a/kernel/sched/core.c
>>> +++ b/kernel/sched/core.c
>>> @@ -3956,6 +3956,8 @@ static int ttwu_runnable(struct task_struct *p, int wake_flags)
>>>  		 * it should preempt the task that is current now.
>>>  		 */
>>>  		wakeup_preempt(rq, p, wake_flags | WF_TTWU_RQ);
>>> +		/* Start accounting wait time. */
>>> +		sched_info_enqueue(rq, p);
>>>  	}
>>>  	ttwu_do_wakeup(p);
>>>  	return 1;
>>
>> So the normal wakeup path goes through enqueue_task() which gets the
>> sched_info_enqueue() callback there. But yes, ttwu_runnable() does not
>> go through that, and needs this additional call.
>>
>> There is one more site in ttwu() that also doesn't go through
>> enqueue_task() and that is the p==current thing at the top.
> 
> The counter already measures how much time a task waits for CPU,
> curr is already is at the CPU so we don't need a call from there.
> 
> Or not?

Yup! on_cpu / task_current() gets dealt at sched_info_switch()
which will enqueue the signal if the task is preempted.

-- 
Thanks and Regards,
Prateek