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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>
16#include <linux/slab.h>
17#include "cpudeadline.h"
18
19static inline int parent(int i)
20{
21 return (i - 1) >> 1;
22}
23
24static inline int left_child(int i)
25{
26 return (i << 1) + 1;
27}
28
29static inline int right_child(int i)
30{
31 return (i << 1) + 2;
32}
33
34static inline int dl_time_before(u64 a, u64 b)
35{
36 return (s64)(a - b) < 0;
37}
38
39static void cpudl_exchange(struct cpudl *cp, int a, int b)
40{
41 int cpu_a = cp->elements[a].cpu, cpu_b = cp->elements[b].cpu;
42
43 swap(cp->elements[a].cpu, cp->elements[b].cpu);
44 swap(cp->elements[a].dl , cp->elements[b].dl );
45
46 swap(cp->elements[cpu_a].idx, cp->elements[cpu_b].idx);
47}
48
49static void cpudl_heapify(struct cpudl *cp, int idx)
50{
51 int l, r, largest;
52
53 /* adapted from lib/prio_heap.c */
54 while(1) {
55 l = left_child(idx);
56 r = right_child(idx);
57 largest = idx;
58
59 if ((l < cp->size) && dl_time_before(cp->elements[idx].dl,
60 cp->elements[l].dl))
61 largest = l;
62 if ((r < cp->size) && dl_time_before(cp->elements[largest].dl,
63 cp->elements[r].dl))
64 largest = r;
65 if (largest == idx)
66 break;
67
68 /* Push idx down the heap one level and bump one up */
69 cpudl_exchange(cp, largest, idx);
70 idx = largest;
71 }
72}
73
74static void cpudl_change_key(struct cpudl *cp, int idx, u64 new_dl)
75{
76 WARN_ON(idx == IDX_INVALID || !cpu_present(idx));
77
78 if (dl_time_before(new_dl, cp->elements[idx].dl)) {
79 cp->elements[idx].dl = new_dl;
80 cpudl_heapify(cp, idx);
81 } else {
82 cp->elements[idx].dl = new_dl;
83 while (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
84 cp->elements[idx].dl)) {
85 cpudl_exchange(cp, idx, parent(idx));
86 idx = parent(idx);
87 }
88 }
89}
90
91static inline int cpudl_maximum(struct cpudl *cp)
92{
93 return cp->elements[0].cpu;
94}
95
96/*
97 * cpudl_find - find the best (later-dl) CPU in the system
98 * @cp: the cpudl max-heap context
99 * @p: the task
100 * @later_mask: a mask to fill in with the selected CPUs (or NULL)
101 *
102 * Returns: int - best CPU (heap maximum if suitable)
103 */
104int cpudl_find(struct cpudl *cp, struct task_struct *p,
105 struct cpumask *later_mask)
106{
107 int best_cpu = -1;
108 const struct sched_dl_entity *dl_se = &p->dl;
109
110 if (later_mask && cpumask_and(later_mask, cp->free_cpus,
111 &p->cpus_allowed) && cpumask_and(later_mask,
112 later_mask, cpu_active_mask)) {
113 best_cpu = cpumask_any(later_mask);
114 goto out;
115 } else if (cpumask_test_cpu(cpudl_maximum(cp), &p->cpus_allowed) &&
116 dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
117 best_cpu = cpudl_maximum(cp);
118 if (later_mask)
119 cpumask_set_cpu(best_cpu, later_mask);
120 }
121
122out:
123 WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
124
125 return best_cpu;
126}
127
128/*
129 * cpudl_set - update the cpudl max-heap
130 * @cp: the cpudl max-heap context
131 * @cpu: the target cpu
132 * @dl: the new earliest deadline for this cpu
133 *
134 * Notes: assumes cpu_rq(cpu)->lock is locked
135 *
136 * Returns: (void)
137 */
138void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
139{
140 int old_idx, new_cpu;
141 unsigned long flags;
142
143 WARN_ON(!cpu_present(cpu));
144
145 raw_spin_lock_irqsave(&cp->lock, flags);
146 old_idx = cp->elements[cpu].idx;
147 if (!is_valid) {
148 /* remove item */
149 if (old_idx == IDX_INVALID) {
150 /*
151 * Nothing to remove if old_idx was invalid.
152 * This could happen if a rq_offline_dl is
153 * called for a CPU without -dl tasks running.
154 */
155 goto out;
156 }
157 new_cpu = cp->elements[cp->size - 1].cpu;
158 cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
159 cp->elements[old_idx].cpu = new_cpu;
160 cp->size--;
161 cp->elements[new_cpu].idx = old_idx;
162 cp->elements[cpu].idx = IDX_INVALID;
163 while (old_idx > 0 && dl_time_before(
164 cp->elements[parent(old_idx)].dl,
165 cp->elements[old_idx].dl)) {
166 cpudl_exchange(cp, old_idx, parent(old_idx));
167 old_idx = parent(old_idx);
168 }
169 cpumask_set_cpu(cpu, cp->free_cpus);
170 cpudl_heapify(cp, old_idx);
171
172 goto out;
173 }
174
175 if (old_idx == IDX_INVALID) {
176 cp->size++;
177 cp->elements[cp->size - 1].dl = 0;
178 cp->elements[cp->size - 1].cpu = cpu;
179 cp->elements[cpu].idx = cp->size - 1;
180 cpudl_change_key(cp, cp->size - 1, dl);
181 cpumask_clear_cpu(cpu, cp->free_cpus);
182 } else {
183 cpudl_change_key(cp, old_idx, dl);
184 }
185
186out:
187 raw_spin_unlock_irqrestore(&cp->lock, flags);
188}
189
190/*
191 * cpudl_init - initialize the cpudl structure
192 * @cp: the cpudl max-heap context
193 */
194int cpudl_init(struct cpudl *cp)
195{
196 int i;
197
198 memset(cp, 0, sizeof(*cp));
199 raw_spin_lock_init(&cp->lock);
200 cp->size = 0;
201
202 cp->elements = kcalloc(nr_cpu_ids,
203 sizeof(struct cpudl_item),
204 GFP_KERNEL);
205 if (!cp->elements)
206 return -ENOMEM;
207
208 if (!alloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
209 kfree(cp->elements);
210 return -ENOMEM;
211 }
212
213 for_each_possible_cpu(i)
214 cp->elements[i].idx = IDX_INVALID;
215
216 cpumask_setall(cp->free_cpus);
217
218 return 0;
219}
220
221/*
222 * cpudl_cleanup - clean up the cpudl structure
223 * @cp: the cpudl max-heap context
224 */
225void cpudl_cleanup(struct cpudl *cp)
226{
227 free_cpumask_var(cp->free_cpus);
228 kfree(cp->elements);
229}
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>
16#include <linux/slab.h>
17#include "cpudeadline.h"
18
19static inline int parent(int i)
20{
21 return (i - 1) >> 1;
22}
23
24static inline int left_child(int i)
25{
26 return (i << 1) + 1;
27}
28
29static inline int right_child(int i)
30{
31 return (i << 1) + 2;
32}
33
34static void cpudl_exchange(struct cpudl *cp, int a, int b)
35{
36 int cpu_a = cp->elements[a].cpu, cpu_b = cp->elements[b].cpu;
37
38 swap(cp->elements[a].cpu, cp->elements[b].cpu);
39 swap(cp->elements[a].dl , cp->elements[b].dl );
40
41 swap(cp->elements[cpu_a].idx, cp->elements[cpu_b].idx);
42}
43
44static void cpudl_heapify(struct cpudl *cp, int idx)
45{
46 int l, r, largest;
47
48 /* adapted from lib/prio_heap.c */
49 while(1) {
50 l = left_child(idx);
51 r = right_child(idx);
52 largest = idx;
53
54 if ((l < cp->size) && dl_time_before(cp->elements[idx].dl,
55 cp->elements[l].dl))
56 largest = l;
57 if ((r < cp->size) && dl_time_before(cp->elements[largest].dl,
58 cp->elements[r].dl))
59 largest = r;
60 if (largest == idx)
61 break;
62
63 /* Push idx down the heap one level and bump one up */
64 cpudl_exchange(cp, largest, idx);
65 idx = largest;
66 }
67}
68
69static void cpudl_change_key(struct cpudl *cp, int idx, u64 new_dl)
70{
71 WARN_ON(idx == IDX_INVALID || !cpu_present(idx));
72
73 if (dl_time_before(new_dl, cp->elements[idx].dl)) {
74 cp->elements[idx].dl = new_dl;
75 cpudl_heapify(cp, idx);
76 } else {
77 cp->elements[idx].dl = new_dl;
78 while (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
79 cp->elements[idx].dl)) {
80 cpudl_exchange(cp, idx, parent(idx));
81 idx = parent(idx);
82 }
83 }
84}
85
86static inline int cpudl_maximum(struct cpudl *cp)
87{
88 return cp->elements[0].cpu;
89}
90
91/*
92 * cpudl_find - find the best (later-dl) CPU in the system
93 * @cp: the cpudl max-heap context
94 * @p: the task
95 * @later_mask: a mask to fill in with the selected CPUs (or NULL)
96 *
97 * Returns: int - best CPU (heap maximum if suitable)
98 */
99int cpudl_find(struct cpudl *cp, struct task_struct *p,
100 struct cpumask *later_mask)
101{
102 int best_cpu = -1;
103 const struct sched_dl_entity *dl_se = &p->dl;
104
105 if (later_mask &&
106 cpumask_and(later_mask, cp->free_cpus, &p->cpus_allowed)) {
107 best_cpu = cpumask_any(later_mask);
108 goto out;
109 } else if (cpumask_test_cpu(cpudl_maximum(cp), &p->cpus_allowed) &&
110 dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
111 best_cpu = cpudl_maximum(cp);
112 if (later_mask)
113 cpumask_set_cpu(best_cpu, later_mask);
114 }
115
116out:
117 WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
118
119 return best_cpu;
120}
121
122/*
123 * cpudl_set - update the cpudl max-heap
124 * @cp: the cpudl max-heap context
125 * @cpu: the target cpu
126 * @dl: the new earliest deadline for this cpu
127 *
128 * Notes: assumes cpu_rq(cpu)->lock is locked
129 *
130 * Returns: (void)
131 */
132void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
133{
134 int old_idx, new_cpu;
135 unsigned long flags;
136
137 WARN_ON(!cpu_present(cpu));
138
139 raw_spin_lock_irqsave(&cp->lock, flags);
140 old_idx = cp->elements[cpu].idx;
141 if (!is_valid) {
142 /* remove item */
143 if (old_idx == IDX_INVALID) {
144 /*
145 * Nothing to remove if old_idx was invalid.
146 * This could happen if a rq_offline_dl is
147 * called for a CPU without -dl tasks running.
148 */
149 goto out;
150 }
151 new_cpu = cp->elements[cp->size - 1].cpu;
152 cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
153 cp->elements[old_idx].cpu = new_cpu;
154 cp->size--;
155 cp->elements[new_cpu].idx = old_idx;
156 cp->elements[cpu].idx = IDX_INVALID;
157 while (old_idx > 0 && dl_time_before(
158 cp->elements[parent(old_idx)].dl,
159 cp->elements[old_idx].dl)) {
160 cpudl_exchange(cp, old_idx, parent(old_idx));
161 old_idx = parent(old_idx);
162 }
163 cpumask_set_cpu(cpu, cp->free_cpus);
164 cpudl_heapify(cp, old_idx);
165
166 goto out;
167 }
168
169 if (old_idx == IDX_INVALID) {
170 cp->size++;
171 cp->elements[cp->size - 1].dl = 0;
172 cp->elements[cp->size - 1].cpu = cpu;
173 cp->elements[cpu].idx = cp->size - 1;
174 cpudl_change_key(cp, cp->size - 1, dl);
175 cpumask_clear_cpu(cpu, cp->free_cpus);
176 } else {
177 cpudl_change_key(cp, old_idx, dl);
178 }
179
180out:
181 raw_spin_unlock_irqrestore(&cp->lock, flags);
182}
183
184/*
185 * cpudl_set_freecpu - Set the cpudl.free_cpus
186 * @cp: the cpudl max-heap context
187 * @cpu: rd attached cpu
188 */
189void cpudl_set_freecpu(struct cpudl *cp, int cpu)
190{
191 cpumask_set_cpu(cpu, cp->free_cpus);
192}
193
194/*
195 * cpudl_clear_freecpu - Clear the cpudl.free_cpus
196 * @cp: the cpudl max-heap context
197 * @cpu: rd attached cpu
198 */
199void cpudl_clear_freecpu(struct cpudl *cp, int cpu)
200{
201 cpumask_clear_cpu(cpu, cp->free_cpus);
202}
203
204/*
205 * cpudl_init - initialize the cpudl structure
206 * @cp: the cpudl max-heap context
207 */
208int cpudl_init(struct cpudl *cp)
209{
210 int i;
211
212 memset(cp, 0, sizeof(*cp));
213 raw_spin_lock_init(&cp->lock);
214 cp->size = 0;
215
216 cp->elements = kcalloc(nr_cpu_ids,
217 sizeof(struct cpudl_item),
218 GFP_KERNEL);
219 if (!cp->elements)
220 return -ENOMEM;
221
222 if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
223 kfree(cp->elements);
224 return -ENOMEM;
225 }
226
227 for_each_possible_cpu(i)
228 cp->elements[i].idx = IDX_INVALID;
229
230 return 0;
231}
232
233/*
234 * cpudl_cleanup - clean up the cpudl structure
235 * @cp: the cpudl max-heap context
236 */
237void cpudl_cleanup(struct cpudl *cp)
238{
239 free_cpumask_var(cp->free_cpus);
240 kfree(cp->elements);
241}