Merge tag 'sched_urgent_for_v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

 *

 * XXX could add max_slice to the augmented data to track this.

 */

static s64 entity_lag(u64 avruntime, struct sched_entity *se)

static void update_entity_lag(struct cfs_rq *cfs_rq, struct sched_entity *se)

{

	s64 vlag, limit;

	vlag = avruntime - se->vruntime;

	limit = calc_delta_fair(max_t(u64, 2*se->slice, TICK_NSEC), se);

	return clamp(vlag, -limit, limit);

}

static void update_entity_lag(struct cfs_rq *cfs_rq, struct sched_entity *se)

{

	SCHED_WARN_ON(!se->on_rq);

	se->vlag = entity_lag(avg_vruntime(cfs_rq), se);

	vlag = avg_vruntime(cfs_rq) - se->vruntime;

	limit = calc_delta_fair(max_t(u64, 2*se->slice, TICK_NSEC), se);

	se->vlag = clamp(vlag, -limit, limit);

}

/*

dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }

#endif

static void reweight_eevdf(struct sched_entity *se, u64 avruntime,

			   unsigned long weight)

{

	unsigned long old_weight = se->load.weight;

	s64 vlag, vslice;

	/*

	 * VRUNTIME

	 * --------

	 *

	 * COROLLARY #1: The virtual runtime of the entity needs to be

	 * adjusted if re-weight at !0-lag point.

	 *

	 * Proof: For contradiction assume this is not true, so we can

	 * re-weight without changing vruntime at !0-lag point.

	 *

	 *             Weight	VRuntime   Avg-VRuntime

	 *     before    w          v            V

	 *      after    w'         v'           V'

	 *

	 * Since lag needs to be preserved through re-weight:

	 *

	 *	lag = (V - v)*w = (V'- v')*w', where v = v'

	 *	==>	V' = (V - v)*w/w' + v		(1)

	 *

	 * Let W be the total weight of the entities before reweight,

	 * since V' is the new weighted average of entities:

	 *

	 *	V' = (WV + w'v - wv) / (W + w' - w)	(2)

	 *

	 * by using (1) & (2) we obtain:

	 *

	 *	(WV + w'v - wv) / (W + w' - w) = (V - v)*w/w' + v

	 *	==> (WV-Wv+Wv+w'v-wv)/(W+w'-w) = (V - v)*w/w' + v

	 *	==> (WV - Wv)/(W + w' - w) + v = (V - v)*w/w' + v

	 *	==>	(V - v)*W/(W + w' - w) = (V - v)*w/w' (3)

	 *

	 * Since we are doing at !0-lag point which means V != v, we

	 * can simplify (3):

	 *

	 *	==>	W / (W + w' - w) = w / w'

	 *	==>	Ww' = Ww + ww' - ww

	 *	==>	W * (w' - w) = w * (w' - w)

	 *	==>	W = w	(re-weight indicates w' != w)

	 *

	 * So the cfs_rq contains only one entity, hence vruntime of

	 * the entity @v should always equal to the cfs_rq's weighted

	 * average vruntime @V, which means we will always re-weight

	 * at 0-lag point, thus breach assumption. Proof completed.

	 *

	 *

	 * COROLLARY #2: Re-weight does NOT affect weighted average

	 * vruntime of all the entities.

	 *

	 * Proof: According to corollary #1, Eq. (1) should be:

	 *

	 *	(V - v)*w = (V' - v')*w'

	 *	==>    v' = V' - (V - v)*w/w'		(4)

	 *

	 * According to the weighted average formula, we have:

	 *

	 *	V' = (WV - wv + w'v') / (W - w + w')

	 *	   = (WV - wv + w'(V' - (V - v)w/w')) / (W - w + w')

	 *	   = (WV - wv + w'V' - Vw + wv) / (W - w + w')

	 *	   = (WV + w'V' - Vw) / (W - w + w')

	 *

	 *	==>  V'*(W - w + w') = WV + w'V' - Vw

	 *	==>	V' * (W - w) = (W - w) * V	(5)

	 *

	 * If the entity is the only one in the cfs_rq, then reweight

	 * always occurs at 0-lag point, so V won't change. Or else

	 * there are other entities, hence W != w, then Eq. (5) turns

	 * into V' = V. So V won't change in either case, proof done.

	 *

	 *

	 * So according to corollary #1 & #2, the effect of re-weight

	 * on vruntime should be:

	 *

	 *	v' = V' - (V - v) * w / w'		(4)

	 *	   = V  - (V - v) * w / w'

	 *	   = V  - vl * w / w'

	 *	   = V  - vl'

	 */

	if (avruntime != se->vruntime) {

		vlag = entity_lag(avruntime, se);

		vlag = div_s64(vlag * old_weight, weight);

		se->vruntime = avruntime - vlag;

	}

	/*

	 * DEADLINE

	 * --------

	 *

	 * When the weight changes, the virtual time slope changes and

	 * we should adjust the relative virtual deadline accordingly.

	 *

	 *	d' = v' + (d - v)*w/w'

	 *	   = V' - (V - v)*w/w' + (d - v)*w/w'

	 *	   = V  - (V - v)*w/w' + (d - v)*w/w'

	 *	   = V  + (d - V)*w/w'

	 */

	vslice = (s64)(se->deadline - avruntime);

	vslice = div_s64(vslice * old_weight, weight);

	se->deadline = avruntime + vslice;

}

static void place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags);

static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,

			    unsigned long weight)

{

	bool curr = cfs_rq->curr == se;

	u64 avruntime;

	if (se->on_rq) {

		/* commit outstanding execution time */

		update_curr(cfs_rq);

		avruntime = avg_vruntime(cfs_rq);

		update_entity_lag(cfs_rq, se);

		se->deadline -= se->vruntime;

		se->rel_deadline = 1;

		if (!curr)

			__dequeue_entity(cfs_rq, se);

		update_load_sub(&cfs_rq->load, se->load.weight);

	}

	dequeue_load_avg(cfs_rq, se);

	if (se->on_rq) {

		reweight_eevdf(se, avruntime, weight);

	} else {

	/*

	 * Because we keep se->vlag = V - v_i, while: lag_i = w_i*(V - v_i),

	 * we need to scale se->vlag when w_i changes.

	 */

	se->vlag = div_s64(se->vlag * se->load.weight, weight);

	}

	if (se->rel_deadline)

		se->deadline = div_s64(se->deadline * se->load.weight, weight);

	update_load_set(&se->load, weight);

	enqueue_load_avg(cfs_rq, se);

	if (se->on_rq) {

		update_load_add(&cfs_rq->load, se->load.weight);

		place_entity(cfs_rq, se, 0);

		if (!curr)

			__enqueue_entity(cfs_rq, se);

	struct cfs_rq *gcfs_rq = group_cfs_rq(se);

	long shares;

	if (!gcfs_rq)

	/*

	 * When a group becomes empty, preserve its weight. This matters for

	 * DELAY_DEQUEUE.

	 */

	if (!gcfs_rq || !gcfs_rq->load.weight)

		return;

	if (throttled_hierarchy(gcfs_rq))

	se->vruntime = vruntime - lag;

	if (sched_feat(PLACE_REL_DEADLINE) && se->rel_deadline) {

	if (se->rel_deadline) {

		se->deadline += se->vruntime;

		se->rel_deadline = 0;

		return;