static int __assign_cfs_rq_runtime(struct cfs_bandwidth *cfs_b,
				   struct cfs_rq *cfs_rq, u64 target_runtime)
{
	u64 min_amount, amount = 0;

	lockdep_assert_held(&cfs_b->lock);

	/* note: this is a positive sum as runtime_remaining <= 0 */
	min_amount = target_runtime - cfs_rq->runtime_remaining;

	if (cfs_b->quota == RUNTIME_INF)
		amount = min_amount;
	else {
		start_cfs_bandwidth(cfs_b);

		if (cfs_b->runtime > 0) {
			amount = min(cfs_b->runtime, min_amount);
			cfs_b->runtime -= amount;
			cfs_b->idle = 0;
		}
	}

	cfs_rq->runtime_remaining += amount;

	return cfs_rq->runtime_remaining > 0;
}

/* returns 0 on failure to allocate runtime */
static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
{
	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
	int ret;

	raw_spin_lock(&cfs_b->lock);
	ret = __assign_cfs_rq_runtime(cfs_b, cfs_rq, sched_cfs_bandwidth_slice());
	raw_spin_unlock(&cfs_b->lock);

	return ret;
}

static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
{
	/* dock delta_exec before expiring quota (as it could span periods) */
	cfs_rq->runtime_remaining -= delta_exec;

	if (likely(cfs_rq->runtime_remaining > 0))
		return;

	if (cfs_rq->throttled)
		return;
	/*
	 * if we're unable to extend our runtime we resched so that the active
	 * hierarchy can be throttled
	 */
	if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
		resched_curr(rq_of(cfs_rq));
}

Échauffement