Re: [PATCH 05/12] sched: Move sched_class::prio_changed() into the change pattern

[Pierre Gondois <pierre.gondois@arm.com>]

Hello Peter,

On 1/15/26 10:05, Peter Zijlstra wrote:
> On Thu, Jan 15, 2026 at 09:24:31AM +0100, Peter Zijlstra wrote:
>> On Wed, Jan 14, 2026 at 03:20:48PM +0100, Juri Lelli wrote:
>>
>>>> --- a/kernel/sched/syscalls.c
>>>> +++ b/kernel/sched/syscalls.c
>>>> @@ -639,7 +639,7 @@ int __sched_setscheduler(struct task_str
>>>>   		 * itself.
>>>>   		 */
>>>>   		newprio = rt_effective_prio(p, newprio);
>>>> -		if (newprio == oldprio)
>>>> +		if (newprio == oldprio && !dl_prio(newprio))
>>>>   			queue_flags &= ~DEQUEUE_MOVE;
>>>>   	}
>>> We have been using (improperly?) ENQUEUE_SAVE also to know when a new
>>> entity gets setscheduled to DEADLINE (or its parameters are changed) and
>>> it looks like this keeps that happening with DEQUEUE_MOVE. So, from a
>>> quick first look, it does sound good to me.
>> If this is strictly about tasks coming into SCHED_DEADLINE there are a
>> number of alternative options:
>>
>>   - there are the sched_class::switch{ing,ed}_to() callbacks;
>>   - there is (the fairly recent) ENQUEUE_CLASS.
>>
>> Anyway, let me break up this one patch into individual bits and write
>> changelogs. I'll stick them in queue/sched/urgent for now; hopefully
>> Pierre can given them a spin and report back if it all sorts his
>> problem).
> Now live at:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/log/?h=sched/urgent
>
> Please test.
I don't see the balance_callback or the double clock update warnings 
anymore.

Thanks for the branch,
Regards,
Pierre