Re: [RFC PATCH v3 00/16] Core scheduling v3

[Aaron Lu <aaron.lu@linux.alibaba.com>]

On Tue, Aug 06, 2019 at 02:19:57PM -0700, Tim Chen wrote:
> +void account_core_idletime(struct task_struct *p, u64 exec)
> +{
> +	const struct cpumask *smt_mask;
> +	struct rq *rq;
> +	bool force_idle, refill;
> +	int i, cpu;
> +
> +	rq = task_rq(p);
> +	if (!sched_core_enabled(rq) || !p->core_cookie)
> +		return;

I don't see why return here for untagged task. Untagged task can also
preempt tagged task and force a CPU thread enter idle state.
Untagged is just another tag to me, unless we want to allow untagged
task to coschedule with a tagged task.

> +	cpu = task_cpu(p);
> +	force_idle = false;
> +	refill = true;
> +	smt_mask = cpu_smt_mask(cpu);
> +
> +	for_each_cpu(i, smt_mask) {
> +		if (cpu == i)
> +			continue;
> +
> +		if (cpu_rq(i)->core_forceidle)
> +			force_idle = true;
> +
> +		/* Only refill if everyone has run out of allowance */
> +		if (cpu_rq(i)->core_idle_allowance > 0)
> +			refill = false;
> +	}
> +
> +	if (force_idle)
> +		rq->core_idle_allowance -= (s64) exec;
> +
> +	if (rq->core_idle_allowance < 0 && refill) {
> +		for_each_cpu(i, smt_mask) {
> +			cpu_rq(i)->core_idle_allowance += (s64) SCHED_IDLE_ALLOWANCE;
> +		}
> +	}
> +}