Re: [PATCH v5 09/14] sched: Add over-utilization/tipping point indicator

[Peter Zijlstra]

On Tue, Jul 24, 2018 at 01:25:16PM +0100, Quentin Perret wrote:
> @@ -5100,8 +5118,17 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
>  		update_cfs_group(se);
>  	}
>  
> -	if (!se)
> +	if (!se) {
>  		add_nr_running(rq, 1);
> +		/*
> +		 * The utilization of a new task is 'wrong' so wait for it
> +		 * to build some utilization history before trying to detect
> +		 * the overutilized flag.
> +		 */
> +		if (flags & ENQUEUE_WAKEUP)
> +			update_overutilized_status(rq);
> +
> +	}
>  
>  	hrtick_update(rq);
>  }

That is a somewhat dodgy hack. There is no guarantee what so ever that
when the task wakes next its history is any better. The comment doesn't
reflect this I feel.