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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// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kernel/sched/cpudeadline.c
4 *
5 * Global CPU deadline management
6 *
7 * Author: Juri Lelli <j.lelli@sssup.it>
8 */
9
10static inline int parent(int i)
11{
12 return (i - 1) >> 1;
13}
14
15static inline int left_child(int i)
16{
17 return (i << 1) + 1;
18}
19
20static inline int right_child(int i)
21{
22 return (i << 1) + 2;
23}
24
25static void cpudl_heapify_down(struct cpudl *cp, int idx)
26{
27 int l, r, largest;
28
29 int orig_cpu = cp->elements[idx].cpu;
30 u64 orig_dl = cp->elements[idx].dl;
31
32 if (left_child(idx) >= cp->size)
33 return;
34
35 /* adapted from lib/prio_heap.c */
36 while (1) {
37 u64 largest_dl;
38
39 l = left_child(idx);
40 r = right_child(idx);
41 largest = idx;
42 largest_dl = orig_dl;
43
44 if ((l < cp->size) && dl_time_before(orig_dl,
45 cp->elements[l].dl)) {
46 largest = l;
47 largest_dl = cp->elements[l].dl;
48 }
49 if ((r < cp->size) && dl_time_before(largest_dl,
50 cp->elements[r].dl))
51 largest = r;
52
53 if (largest == idx)
54 break;
55
56 /* pull largest child onto idx */
57 cp->elements[idx].cpu = cp->elements[largest].cpu;
58 cp->elements[idx].dl = cp->elements[largest].dl;
59 cp->elements[cp->elements[idx].cpu].idx = idx;
60 idx = largest;
61 }
62 /* actual push down of saved original values orig_* */
63 cp->elements[idx].cpu = orig_cpu;
64 cp->elements[idx].dl = orig_dl;
65 cp->elements[cp->elements[idx].cpu].idx = idx;
66}
67
68static void cpudl_heapify_up(struct cpudl *cp, int idx)
69{
70 int p;
71
72 int orig_cpu = cp->elements[idx].cpu;
73 u64 orig_dl = cp->elements[idx].dl;
74
75 if (idx == 0)
76 return;
77
78 do {
79 p = parent(idx);
80 if (dl_time_before(orig_dl, cp->elements[p].dl))
81 break;
82 /* pull parent onto idx */
83 cp->elements[idx].cpu = cp->elements[p].cpu;
84 cp->elements[idx].dl = cp->elements[p].dl;
85 cp->elements[cp->elements[idx].cpu].idx = idx;
86 idx = p;
87 } while (idx != 0);
88 /* actual push up of saved original values orig_* */
89 cp->elements[idx].cpu = orig_cpu;
90 cp->elements[idx].dl = orig_dl;
91 cp->elements[cp->elements[idx].cpu].idx = idx;
92}
93
94static void cpudl_heapify(struct cpudl *cp, int idx)
95{
96 if (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
97 cp->elements[idx].dl))
98 cpudl_heapify_up(cp, idx);
99 else
100 cpudl_heapify_down(cp, idx);
101}
102
103static inline int cpudl_maximum(struct cpudl *cp)
104{
105 return cp->elements[0].cpu;
106}
107
108/*
109 * cpudl_find - find the best (later-dl) CPU in the system
110 * @cp: the cpudl max-heap context
111 * @p: the task
112 * @later_mask: a mask to fill in with the selected CPUs (or NULL)
113 *
114 * Returns: int - CPUs were found
115 */
116int cpudl_find(struct cpudl *cp, struct task_struct *p,
117 struct cpumask *later_mask)
118{
119 const struct sched_dl_entity *dl_se = &p->dl;
120
121 if (later_mask &&
122 cpumask_and(later_mask, cp->free_cpus, &p->cpus_mask)) {
123 unsigned long cap, max_cap = 0;
124 int cpu, max_cpu = -1;
125
126 if (!sched_asym_cpucap_active())
127 return 1;
128
129 /* Ensure the capacity of the CPUs fits the task. */
130 for_each_cpu(cpu, later_mask) {
131 if (!dl_task_fits_capacity(p, cpu)) {
132 cpumask_clear_cpu(cpu, later_mask);
133
134 cap = arch_scale_cpu_capacity(cpu);
135
136 if (cap > max_cap ||
137 (cpu == task_cpu(p) && cap == max_cap)) {
138 max_cap = cap;
139 max_cpu = cpu;
140 }
141 }
142 }
143
144 if (cpumask_empty(later_mask))
145 cpumask_set_cpu(max_cpu, later_mask);
146
147 return 1;
148 } else {
149 int best_cpu = cpudl_maximum(cp);
150
151 WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
152
153 if (cpumask_test_cpu(best_cpu, &p->cpus_mask) &&
154 dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
155 if (later_mask)
156 cpumask_set_cpu(best_cpu, later_mask);
157
158 return 1;
159 }
160 }
161 return 0;
162}
163
164/*
165 * cpudl_clear - remove a CPU from the cpudl max-heap
166 * @cp: the cpudl max-heap context
167 * @cpu: the target CPU
168 *
169 * Notes: assumes cpu_rq(cpu)->lock is locked
170 *
171 * Returns: (void)
172 */
173void cpudl_clear(struct cpudl *cp, int cpu)
174{
175 int old_idx, new_cpu;
176 unsigned long flags;
177
178 WARN_ON(!cpu_present(cpu));
179
180 raw_spin_lock_irqsave(&cp->lock, flags);
181
182 old_idx = cp->elements[cpu].idx;
183 if (old_idx == IDX_INVALID) {
184 /*
185 * Nothing to remove if old_idx was invalid.
186 * This could happen if a rq_offline_dl is
187 * called for a CPU without -dl tasks running.
188 */
189 } else {
190 new_cpu = cp->elements[cp->size - 1].cpu;
191 cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
192 cp->elements[old_idx].cpu = new_cpu;
193 cp->size--;
194 cp->elements[new_cpu].idx = old_idx;
195 cp->elements[cpu].idx = IDX_INVALID;
196 cpudl_heapify(cp, old_idx);
197
198 cpumask_set_cpu(cpu, cp->free_cpus);
199 }
200 raw_spin_unlock_irqrestore(&cp->lock, flags);
201}
202
203/*
204 * cpudl_set - update the cpudl max-heap
205 * @cp: the cpudl max-heap context
206 * @cpu: the target CPU
207 * @dl: the new earliest deadline for this CPU
208 *
209 * Notes: assumes cpu_rq(cpu)->lock is locked
210 *
211 * Returns: (void)
212 */
213void cpudl_set(struct cpudl *cp, int cpu, u64 dl)
214{
215 int old_idx;
216 unsigned long flags;
217
218 WARN_ON(!cpu_present(cpu));
219
220 raw_spin_lock_irqsave(&cp->lock, flags);
221
222 old_idx = cp->elements[cpu].idx;
223 if (old_idx == IDX_INVALID) {
224 int new_idx = cp->size++;
225
226 cp->elements[new_idx].dl = dl;
227 cp->elements[new_idx].cpu = cpu;
228 cp->elements[cpu].idx = new_idx;
229 cpudl_heapify_up(cp, new_idx);
230 cpumask_clear_cpu(cpu, cp->free_cpus);
231 } else {
232 cp->elements[old_idx].dl = dl;
233 cpudl_heapify(cp, old_idx);
234 }
235
236 raw_spin_unlock_irqrestore(&cp->lock, flags);
237}
238
239/*
240 * cpudl_set_freecpu - Set the cpudl.free_cpus
241 * @cp: the cpudl max-heap context
242 * @cpu: rd attached CPU
243 */
244void cpudl_set_freecpu(struct cpudl *cp, int cpu)
245{
246 cpumask_set_cpu(cpu, cp->free_cpus);
247}
248
249/*
250 * cpudl_clear_freecpu - Clear the cpudl.free_cpus
251 * @cp: the cpudl max-heap context
252 * @cpu: rd attached CPU
253 */
254void cpudl_clear_freecpu(struct cpudl *cp, int cpu)
255{
256 cpumask_clear_cpu(cpu, cp->free_cpus);
257}
258
259/*
260 * cpudl_init - initialize the cpudl structure
261 * @cp: the cpudl max-heap context
262 */
263int cpudl_init(struct cpudl *cp)
264{
265 int i;
266
267 raw_spin_lock_init(&cp->lock);
268 cp->size = 0;
269
270 cp->elements = kcalloc(nr_cpu_ids,
271 sizeof(struct cpudl_item),
272 GFP_KERNEL);
273 if (!cp->elements)
274 return -ENOMEM;
275
276 if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
277 kfree(cp->elements);
278 return -ENOMEM;
279 }
280
281 for_each_possible_cpu(i)
282 cp->elements[i].idx = IDX_INVALID;
283
284 return 0;
285}
286
287/*
288 * cpudl_cleanup - clean up the cpudl structure
289 * @cp: the cpudl max-heap context
290 */
291void cpudl_cleanup(struct cpudl *cp)
292{
293 free_cpumask_var(cp->free_cpus);
294 kfree(cp->elements);
295}