[mirror_ubuntu-zesty-kernel.git] / kernel / sched / cpudeadline.c

/*
 *  kernel/sched/cpudl.c
 *
 *  Global CPU deadline management
 *
 *  Author: Juri Lelli <j.lelli@sssup.it>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; version 2
 *  of the License.
 */

#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include "cpudeadline.h"

static inline int parent(int i)
{
	return (i - 1) >> 1;
}

static inline int left_child(int i)
{
	return (i << 1) + 1;
}

static inline int right_child(int i)
{
	return (i << 1) + 2;
}

static void cpudl_heapify_down(struct cpudl *cp, int idx)
{
	int l, r, largest;

	int orig_cpu = cp->elements[idx].cpu;
	u64 orig_dl = cp->elements[idx].dl;

	if (left_child(idx) >= cp->size)
		return;

	/* adapted from lib/prio_heap.c */
	while(1) {
		u64 largest_dl;
		l = left_child(idx);
		r = right_child(idx);
		largest = idx;
		largest_dl = orig_dl;

		if ((l < cp->size) && dl_time_before(orig_dl,
						cp->elements[l].dl)) {
			largest = l;
			largest_dl = cp->elements[l].dl;
		}
		if ((r < cp->size) && dl_time_before(largest_dl,
						cp->elements[r].dl))
			largest = r;

		if (largest == idx)
			break;

		/* pull largest child onto idx */
		cp->elements[idx].cpu = cp->elements[largest].cpu;
		cp->elements[idx].dl = cp->elements[largest].dl;
		cp->elements[cp->elements[idx].cpu].idx = idx;
		idx = largest;
	}
	/* actual push down of saved original values orig_* */
	cp->elements[idx].cpu = orig_cpu;
	cp->elements[idx].dl = orig_dl;
	cp->elements[cp->elements[idx].cpu].idx = idx;
}

static void cpudl_heapify_up(struct cpudl *cp, int idx)
{
	int p;

	int orig_cpu = cp->elements[idx].cpu;
	u64 orig_dl = cp->elements[idx].dl;

	if (idx == 0)
		return;

	do {
		p = parent(idx);
		if (dl_time_before(orig_dl, cp->elements[p].dl))
			break;
		/* pull parent onto idx */
		cp->elements[idx].cpu = cp->elements[p].cpu;
		cp->elements[idx].dl = cp->elements[p].dl;
		cp->elements[cp->elements[idx].cpu].idx = idx;
		idx = p;
	} while (idx != 0);
	/* actual push up of saved original values orig_* */
	cp->elements[idx].cpu = orig_cpu;
	cp->elements[idx].dl = orig_dl;
	cp->elements[cp->elements[idx].cpu].idx = idx;
}

static void cpudl_heapify(struct cpudl *cp, int idx)
{
	if (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
				cp->elements[idx].dl))
		cpudl_heapify_up(cp, idx);
	else
		cpudl_heapify_down(cp, idx);
}

static inline int cpudl_maximum(struct cpudl *cp)
{
	return cp->elements[0].cpu;
}

/*
 * cpudl_find - find the best (later-dl) CPU in the system
 * @cp: the cpudl max-heap context
 * @p: the task
 * @later_mask: a mask to fill in with the selected CPUs (or NULL)
 *
 * Returns: int - best CPU (heap maximum if suitable)
 */
int cpudl_find(struct cpudl *cp, struct task_struct *p,
	       struct cpumask *later_mask)
{
	int best_cpu = -1;
	const struct sched_dl_entity *dl_se = &p->dl;

	if (later_mask &&
	    cpumask_and(later_mask, cp->free_cpus, tsk_cpus_allowed(p))) {
		best_cpu = cpumask_any(later_mask);
		goto out;
	} else if (cpumask_test_cpu(cpudl_maximum(cp), tsk_cpus_allowed(p)) &&
			dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
		best_cpu = cpudl_maximum(cp);
		if (later_mask)
			cpumask_set_cpu(best_cpu, later_mask);
	}

out:
	WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));

	return best_cpu;
}

/*
 * cpudl_clear - remove a cpu from the cpudl max-heap
 * @cp: the cpudl max-heap context
 * @cpu: the target cpu
 *
 * Notes: assumes cpu_rq(cpu)->lock is locked
 *
 * Returns: (void)
 */
void cpudl_clear(struct cpudl *cp, int cpu)
{
	int old_idx, new_cpu;
	unsigned long flags;

	WARN_ON(!cpu_present(cpu));

	raw_spin_lock_irqsave(&cp->lock, flags);

	old_idx = cp->elements[cpu].idx;
	if (old_idx == IDX_INVALID) {
		/*
		 * Nothing to remove if old_idx was invalid.
		 * This could happen if a rq_offline_dl is
		 * called for a CPU without -dl tasks running.
		 */
	} else {
		new_cpu = cp->elements[cp->size - 1].cpu;
		cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
		cp->elements[old_idx].cpu = new_cpu;
		cp->size--;
		cp->elements[new_cpu].idx = old_idx;
		cp->elements[cpu].idx = IDX_INVALID;
		cpudl_heapify(cp, old_idx);

		cpumask_set_cpu(cpu, cp->free_cpus);
	}
	raw_spin_unlock_irqrestore(&cp->lock, flags);
}

/*
 * cpudl_set - update the cpudl max-heap
 * @cp: the cpudl max-heap context
 * @cpu: the target cpu
 * @dl: the new earliest deadline for this cpu
 *
 * Notes: assumes cpu_rq(cpu)->lock is locked
 *
 * Returns: (void)
 */
void cpudl_set(struct cpudl *cp, int cpu, u64 dl)
{
	int old_idx;
	unsigned long flags;

	WARN_ON(!cpu_present(cpu));

	raw_spin_lock_irqsave(&cp->lock, flags);

	old_idx = cp->elements[cpu].idx;
	if (old_idx == IDX_INVALID) {
		int new_idx = cp->size++;
		cp->elements[new_idx].dl = dl;
		cp->elements[new_idx].cpu = cpu;
		cp->elements[cpu].idx = new_idx;
		cpudl_heapify_up(cp, new_idx);
		cpumask_clear_cpu(cpu, cp->free_cpus);
	} else {
		cp->elements[old_idx].dl = dl;
		cpudl_heapify(cp, old_idx);
	}

	raw_spin_unlock_irqrestore(&cp->lock, flags);
}

/*
 * cpudl_set_freecpu - Set the cpudl.free_cpus
 * @cp: the cpudl max-heap context
 * @cpu: rd attached cpu
 */
void cpudl_set_freecpu(struct cpudl *cp, int cpu)
{
	cpumask_set_cpu(cpu, cp->free_cpus);
}

/*
 * cpudl_clear_freecpu - Clear the cpudl.free_cpus
 * @cp: the cpudl max-heap context
 * @cpu: rd attached cpu
 */
void cpudl_clear_freecpu(struct cpudl *cp, int cpu)
{
	cpumask_clear_cpu(cpu, cp->free_cpus);
}

/*
 * cpudl_init - initialize the cpudl structure
 * @cp: the cpudl max-heap context
 */
int cpudl_init(struct cpudl *cp)
{
	int i;

	memset(cp, 0, sizeof(*cp));
	raw_spin_lock_init(&cp->lock);
	cp->size = 0;

	cp->elements = kcalloc(nr_cpu_ids,
			       sizeof(struct cpudl_item),
			       GFP_KERNEL);
	if (!cp->elements)
		return -ENOMEM;

	if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
		kfree(cp->elements);
		return -ENOMEM;
	}

	for_each_possible_cpu(i)
		cp->elements[i].idx = IDX_INVALID;

	return 0;
}

/*
 * cpudl_cleanup - clean up the cpudl structure
 * @cp: the cpudl max-heap context
 */
void cpudl_cleanup(struct cpudl *cp)
{
	free_cpumask_var(cp->free_cpus);
	kfree(cp->elements);
}
Commit	Line	Data
6bfd6d72 JL	1	/*
	2	* kernel/sched/cpudl.c
	3	*
	4	* Global CPU deadline management
	5	*
	6	* Author: Juri Lelli <j.lelli@sssup.it>
	7	*
	8	* This program is free software; you can redistribute it and/or
	9	* modify it under the terms of the GNU General Public License
	10	* as published by the Free Software Foundation; version 2
	11	* of the License.
	12	*/
	13
	14	#include <linux/gfp.h>
	15	#include <linux/kernel.h>
944770ab	16	#include <linux/slab.h>
6bfd6d72 JL	17	#include "cpudeadline.h"
	18
	19	static inline int parent(int i)
	20	{
	21	return (i - 1) >> 1;
	22	}
	23
	24	static inline int left_child(int i)
	25	{
	26	return (i << 1) + 1;
	27	}
	28
	29	static inline int right_child(int i)
	30	{
	31	return (i << 1) + 2;
	32	}
	33
126b3b68	34	static void cpudl_heapify_down(struct cpudl *cp, int idx)
6bfd6d72 JL	35	{
	36	int l, r, largest;
	37
8e1bc301 TC	38	int orig_cpu = cp->elements[idx].cpu;
	39	u64 orig_dl = cp->elements[idx].dl;
	40
	41	if (left_child(idx) >= cp->size)
	42	return;
	43
6bfd6d72 JL	44	/* adapted from lib/prio_heap.c */
6bfd6d72 JL	45	while(1) {
8e1bc301	46	u64 largest_dl;
6bfd6d72 JL	47	l = left_child(idx);
	48	r = right_child(idx);
	49	largest = idx;
8e1bc301	50	largest_dl = orig_dl;
6bfd6d72	51
8e1bc301 TC	52	if ((l < cp->size) && dl_time_before(orig_dl,
8e1bc301 TC	53	cp->elements[l].dl)) {
6bfd6d72	54	largest = l;
8e1bc301 TC	55	largest_dl = cp->elements[l].dl;
	56	}
	57	if ((r < cp->size) && dl_time_before(largest_dl,
	58	cp->elements[r].dl))
6bfd6d72	59	largest = r;
8e1bc301	60
6bfd6d72 JL	61	if (largest == idx)
	62	break;
	63
8e1bc301 TC	64	/* pull largest child onto idx */
	65	cp->elements[idx].cpu = cp->elements[largest].cpu;
	66	cp->elements[idx].dl = cp->elements[largest].dl;
	67	cp->elements[cp->elements[idx].cpu].idx = idx;
6bfd6d72 JL	68	idx = largest;
6bfd6d72 JL	69	}
8e1bc301 TC	70	/* actual push down of saved original values orig_* */
	71	cp->elements[idx].cpu = orig_cpu;
	72	cp->elements[idx].dl = orig_dl;
	73	cp->elements[cp->elements[idx].cpu].idx = idx;
6bfd6d72 JL	74	}
6bfd6d72 JL	75
126b3b68	76	static void cpudl_heapify_up(struct cpudl *cp, int idx)
6bfd6d72	77	{
8e1bc301 TC	78	int p;
	79
	80	int orig_cpu = cp->elements[idx].cpu;
	81	u64 orig_dl = cp->elements[idx].dl;
	82
	83	if (idx == 0)
	84	return;
	85
	86	do {
	87	p = parent(idx);
	88	if (dl_time_before(orig_dl, cp->elements[p].dl))
	89	break;
	90	/* pull parent onto idx */
	91	cp->elements[idx].cpu = cp->elements[p].cpu;
	92	cp->elements[idx].dl = cp->elements[p].dl;
	93	cp->elements[cp->elements[idx].cpu].idx = idx;
	94	idx = p;
	95	} while (idx != 0);
	96	/* actual push up of saved original values orig_* */
	97	cp->elements[idx].cpu = orig_cpu;
	98	cp->elements[idx].dl = orig_dl;
	99	cp->elements[cp->elements[idx].cpu].idx = idx;
6bfd6d72 JL	100	}
6bfd6d72 JL	101
126b3b68 TC	102	static void cpudl_heapify(struct cpudl *cp, int idx)
	103	{
	104	if (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
	105	cp->elements[idx].dl))
	106	cpudl_heapify_up(cp, idx);
	107	else
	108	cpudl_heapify_down(cp, idx);
	109	}
	110
6bfd6d72 JL	111	static inline int cpudl_maximum(struct cpudl *cp)
	112	{
	113	return cp->elements[0].cpu;
	114	}
	115
	116	/*
	117	* cpudl_find - find the best (later-dl) CPU in the system
	118	* @cp: the cpudl max-heap context
	119	* @p: the task
	120	* @later_mask: a mask to fill in with the selected CPUs (or NULL)
	121	*
	122	* Returns: int - best CPU (heap maximum if suitable)
	123	*/
	124	int cpudl_find(struct cpudl cp, struct task_struct p,
	125	struct cpumask *later_mask)
	126	{
	127	int best_cpu = -1;
	128	const struct sched_dl_entity *dl_se = &p->dl;
	129
16b26943	130	if (later_mask &&
ade42e09	131	cpumask_and(later_mask, cp->free_cpus, tsk_cpus_allowed(p))) {
6bfd6d72 JL	132	best_cpu = cpumask_any(later_mask);
6bfd6d72 JL	133	goto out;
ade42e09	134	} else if (cpumask_test_cpu(cpudl_maximum(cp), tsk_cpus_allowed(p)) &&
6bfd6d72 JL	135	dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
	136	best_cpu = cpudl_maximum(cp);
	137	if (later_mask)
	138	cpumask_set_cpu(best_cpu, later_mask);
	139	}
	140
	141	out:
eec751ed	142	WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
6bfd6d72 JL	143
	144	return best_cpu;
	145	}
	146
	147	/*
d8206bb3	148	* cpudl_clear - remove a cpu from the cpudl max-heap
6bfd6d72 JL	149	* @cp: the cpudl max-heap context
6bfd6d72 JL	150	* @cpu: the target cpu
6bfd6d72 JL	151	*
	152	* Notes: assumes cpu_rq(cpu)->lock is locked
	153	*
	154	* Returns: (void)
	155	*/
d8206bb3	156	void cpudl_clear(struct cpudl *cp, int cpu)
6bfd6d72 JL	157	{
	158	int old_idx, new_cpu;
	159	unsigned long flags;
	160
82b95800	161	WARN_ON(!cpu_present(cpu));
6bfd6d72 JL	162
6bfd6d72 JL	163	raw_spin_lock_irqsave(&cp->lock, flags);
d8206bb3	164
944770ab	165	old_idx = cp->elements[cpu].idx;
d8206bb3 TC	166	if (old_idx == IDX_INVALID) {
	167	/*
	168	* Nothing to remove if old_idx was invalid.
	169	* This could happen if a rq_offline_dl is
	170	* called for a CPU without -dl tasks running.
	171	*/
	172	} else {
6bfd6d72 JL	173	new_cpu = cp->elements[cp->size - 1].cpu;
	174	cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
	175	cp->elements[old_idx].cpu = new_cpu;
	176	cp->size--;
944770ab PZ	177	cp->elements[new_cpu].idx = old_idx;
944770ab PZ	178	cp->elements[cpu].idx = IDX_INVALID;
126b3b68	179	cpudl_heapify(cp, old_idx);
6bfd6d72	180
d8206bb3	181	cpumask_set_cpu(cpu, cp->free_cpus);
6bfd6d72	182	}
d8206bb3 TC	183	raw_spin_unlock_irqrestore(&cp->lock, flags);
	184	}
	185
	186	/*
	187	* cpudl_set - update the cpudl max-heap
	188	* @cp: the cpudl max-heap context
	189	* @cpu: the target cpu
	190	* @dl: the new earliest deadline for this cpu
	191	*
	192	* Notes: assumes cpu_rq(cpu)->lock is locked
	193	*
	194	* Returns: (void)
	195	*/
	196	void cpudl_set(struct cpudl *cp, int cpu, u64 dl)
	197	{
	198	int old_idx;
	199	unsigned long flags;
	200
	201	WARN_ON(!cpu_present(cpu));
6bfd6d72	202
d8206bb3 TC	203	raw_spin_lock_irqsave(&cp->lock, flags);
	204
	205	old_idx = cp->elements[cpu].idx;
6bfd6d72	206	if (old_idx == IDX_INVALID) {
126b3b68 TC	207	int new_idx = cp->size++;
	208	cp->elements[new_idx].dl = dl;
	209	cp->elements[new_idx].cpu = cpu;
	210	cp->elements[cpu].idx = new_idx;
	211	cpudl_heapify_up(cp, new_idx);
6bfd6d72 JL	212	cpumask_clear_cpu(cpu, cp->free_cpus);
6bfd6d72 JL	213	} else {
126b3b68 TC	214	cp->elements[old_idx].dl = dl;
126b3b68 TC	215	cpudl_heapify(cp, old_idx);
6bfd6d72 JL	216	}
6bfd6d72 JL	217
6bfd6d72 JL	218	raw_spin_unlock_irqrestore(&cp->lock, flags);
	219	}
	220
16b26943 XP	221	/*
	222	* cpudl_set_freecpu - Set the cpudl.free_cpus
	223	* @cp: the cpudl max-heap context
	224	* @cpu: rd attached cpu
	225	*/
	226	void cpudl_set_freecpu(struct cpudl *cp, int cpu)
	227	{
	228	cpumask_set_cpu(cpu, cp->free_cpus);
	229	}
	230
	231	/*
	232	* cpudl_clear_freecpu - Clear the cpudl.free_cpus
	233	* @cp: the cpudl max-heap context
	234	* @cpu: rd attached cpu
	235	*/
	236	void cpudl_clear_freecpu(struct cpudl *cp, int cpu)
	237	{
	238	cpumask_clear_cpu(cpu, cp->free_cpus);
	239	}
	240
6bfd6d72 JL	241	/*
	242	* cpudl_init - initialize the cpudl structure
	243	* @cp: the cpudl max-heap context
	244	*/
	245	int cpudl_init(struct cpudl *cp)
	246	{
	247	int i;
	248
	249	memset(cp, 0, sizeof(*cp));
	250	raw_spin_lock_init(&cp->lock);
	251	cp->size = 0;
944770ab PZ	252
	253	cp->elements = kcalloc(nr_cpu_ids,
	254	sizeof(struct cpudl_item),
	255	GFP_KERNEL);
	256	if (!cp->elements)
	257	return -ENOMEM;
	258
16b26943	259	if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
944770ab	260	kfree(cp->elements);
6bfd6d72	261	return -ENOMEM;
944770ab PZ	262	}
	263
	264	for_each_possible_cpu(i)
	265	cp->elements[i].idx = IDX_INVALID;
	266
6bfd6d72 JL	267	return 0;
	268	}
	269
	270	/*
	271	* cpudl_cleanup - clean up the cpudl structure
	272	* @cp: the cpudl max-heap context
	273	*/
	274	void cpudl_cleanup(struct cpudl *cp)
	275	{
6a7cd273	276	free_cpumask_var(cp->free_cpus);
944770ab	277	kfree(cp->elements);
6bfd6d72	278	}