Re: [RFC 1/8] sched: Add nice value change notifier

Wanghui (John)
2021-10-06T04:10:27Z

HI Tvrtko

On 2021/10/4 22:36, Tvrtko Ursulin wrote:
> void set_user_nice(struct task_struct *p, long nice)
> {
> bool queued, running;
> - int old_prio;
> + int old_prio, ret;
> struct rq_flags rf;
> struct rq *rq;
>
> @@ -6915,6 +6947,9 @@ void set_user_nice(struct task_struct *p, long nice)
>
> out_unlock:
> task_rq_unlock(rq, p, &rf);
> +
> + ret = atomic_notifier_call_chain(&user_nice_notifier_list, nice, p);
> + WARN_ON_ONCE(ret != NOTIFY_DONE);
> }
How about adding a new "io_nice" to task_struct，and move the call chain to
sched_setattr/getattr, there are two benefits:

1. Decoupled with fair scheduelr. In our use case, high priority tasks often
use rt scheduler.
2. The range of value don't need to be bound to -20~19 or 0~139