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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 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}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kernel/sched/cpudl.c
4 *
5 * Global CPU deadline management
6 *
7 * Author: Juri Lelli <j.lelli@sssup.it>
8 */
9#include "sched.h"
10
11static inline int parent(int i)
12{
13 return (i - 1) >> 1;
14}
15
16static inline int left_child(int i)
17{
18 return (i << 1) + 1;
19}
20
21static inline int right_child(int i)
22{
23 return (i << 1) + 2;
24}
25
26static void cpudl_heapify_down(struct cpudl *cp, int idx)
27{
28 int l, r, largest;
29
30 int orig_cpu = cp->elements[idx].cpu;
31 u64 orig_dl = cp->elements[idx].dl;
32
33 if (left_child(idx) >= cp->size)
34 return;
35
36 /* adapted from lib/prio_heap.c */
37 while (1) {
38 u64 largest_dl;
39
40 l = left_child(idx);
41 r = right_child(idx);
42 largest = idx;
43 largest_dl = orig_dl;
44
45 if ((l < cp->size) && dl_time_before(orig_dl,
46 cp->elements[l].dl)) {
47 largest = l;
48 largest_dl = cp->elements[l].dl;
49 }
50 if ((r < cp->size) && dl_time_before(largest_dl,
51 cp->elements[r].dl))
52 largest = r;
53
54 if (largest == idx)
55 break;
56
57 /* pull largest child onto idx */
58 cp->elements[idx].cpu = cp->elements[largest].cpu;
59 cp->elements[idx].dl = cp->elements[largest].dl;
60 cp->elements[cp->elements[idx].cpu].idx = idx;
61 idx = largest;
62 }
63 /* actual push down of saved original values orig_* */
64 cp->elements[idx].cpu = orig_cpu;
65 cp->elements[idx].dl = orig_dl;
66 cp->elements[cp->elements[idx].cpu].idx = idx;
67}
68
69static void cpudl_heapify_up(struct cpudl *cp, int idx)
70{
71 int p;
72
73 int orig_cpu = cp->elements[idx].cpu;
74 u64 orig_dl = cp->elements[idx].dl;
75
76 if (idx == 0)
77 return;
78
79 do {
80 p = parent(idx);
81 if (dl_time_before(orig_dl, cp->elements[p].dl))
82 break;
83 /* pull parent onto idx */
84 cp->elements[idx].cpu = cp->elements[p].cpu;
85 cp->elements[idx].dl = cp->elements[p].dl;
86 cp->elements[cp->elements[idx].cpu].idx = idx;
87 idx = p;
88 } while (idx != 0);
89 /* actual push up of saved original values orig_* */
90 cp->elements[idx].cpu = orig_cpu;
91 cp->elements[idx].dl = orig_dl;
92 cp->elements[cp->elements[idx].cpu].idx = idx;
93}
94
95static void cpudl_heapify(struct cpudl *cp, int idx)
96{
97 if (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
98 cp->elements[idx].dl))
99 cpudl_heapify_up(cp, idx);
100 else
101 cpudl_heapify_down(cp, idx);
102}
103
104static inline int cpudl_maximum(struct cpudl *cp)
105{
106 return cp->elements[0].cpu;
107}
108
109/*
110 * cpudl_find - find the best (later-dl) CPU in the system
111 * @cp: the cpudl max-heap context
112 * @p: the task
113 * @later_mask: a mask to fill in with the selected CPUs (or NULL)
114 *
115 * Returns: int - CPUs were found
116 */
117int cpudl_find(struct cpudl *cp, struct task_struct *p,
118 struct cpumask *later_mask)
119{
120 const struct sched_dl_entity *dl_se = &p->dl;
121
122 if (later_mask &&
123 cpumask_and(later_mask, cp->free_cpus, p->cpus_ptr)) {
124 unsigned long cap, max_cap = 0;
125 int cpu, max_cpu = -1;
126
127 if (!static_branch_unlikely(&sched_asym_cpucapacity))
128 return 1;
129
130 /* Ensure the capacity of the CPUs fits the task. */
131 for_each_cpu(cpu, later_mask) {
132 if (!dl_task_fits_capacity(p, cpu)) {
133 cpumask_clear_cpu(cpu, later_mask);
134
135 cap = capacity_orig_of(cpu);
136
137 if (cap > max_cap ||
138 (cpu == task_cpu(p) && cap == max_cap)) {
139 max_cap = cap;
140 max_cpu = cpu;
141 }
142 }
143 }
144
145 if (cpumask_empty(later_mask))
146 cpumask_set_cpu(max_cpu, later_mask);
147
148 return 1;
149 } else {
150 int best_cpu = cpudl_maximum(cp);
151
152 WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
153
154 if (cpumask_test_cpu(best_cpu, p->cpus_ptr) &&
155 dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
156 if (later_mask)
157 cpumask_set_cpu(best_cpu, later_mask);
158
159 return 1;
160 }
161 }
162 return 0;
163}
164
165/*
166 * cpudl_clear - remove a CPU from the cpudl max-heap
167 * @cp: the cpudl max-heap context
168 * @cpu: the target CPU
169 *
170 * Notes: assumes cpu_rq(cpu)->lock is locked
171 *
172 * Returns: (void)
173 */
174void cpudl_clear(struct cpudl *cp, int cpu)
175{
176 int old_idx, new_cpu;
177 unsigned long flags;
178
179 WARN_ON(!cpu_present(cpu));
180
181 raw_spin_lock_irqsave(&cp->lock, flags);
182
183 old_idx = cp->elements[cpu].idx;
184 if (old_idx == IDX_INVALID) {
185 /*
186 * Nothing to remove if old_idx was invalid.
187 * This could happen if a rq_offline_dl is
188 * called for a CPU without -dl tasks running.
189 */
190 } else {
191 new_cpu = cp->elements[cp->size - 1].cpu;
192 cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
193 cp->elements[old_idx].cpu = new_cpu;
194 cp->size--;
195 cp->elements[new_cpu].idx = old_idx;
196 cp->elements[cpu].idx = IDX_INVALID;
197 cpudl_heapify(cp, old_idx);
198
199 cpumask_set_cpu(cpu, cp->free_cpus);
200 }
201 raw_spin_unlock_irqrestore(&cp->lock, flags);
202}
203
204/*
205 * cpudl_set - update the cpudl max-heap
206 * @cp: the cpudl max-heap context
207 * @cpu: the target CPU
208 * @dl: the new earliest deadline for this CPU
209 *
210 * Notes: assumes cpu_rq(cpu)->lock is locked
211 *
212 * Returns: (void)
213 */
214void cpudl_set(struct cpudl *cp, int cpu, u64 dl)
215{
216 int old_idx;
217 unsigned long flags;
218
219 WARN_ON(!cpu_present(cpu));
220
221 raw_spin_lock_irqsave(&cp->lock, flags);
222
223 old_idx = cp->elements[cpu].idx;
224 if (old_idx == IDX_INVALID) {
225 int new_idx = cp->size++;
226
227 cp->elements[new_idx].dl = dl;
228 cp->elements[new_idx].cpu = cpu;
229 cp->elements[cpu].idx = new_idx;
230 cpudl_heapify_up(cp, new_idx);
231 cpumask_clear_cpu(cpu, cp->free_cpus);
232 } else {
233 cp->elements[old_idx].dl = dl;
234 cpudl_heapify(cp, old_idx);
235 }
236
237 raw_spin_unlock_irqrestore(&cp->lock, flags);
238}
239
240/*
241 * cpudl_set_freecpu - Set the cpudl.free_cpus
242 * @cp: the cpudl max-heap context
243 * @cpu: rd attached CPU
244 */
245void cpudl_set_freecpu(struct cpudl *cp, int cpu)
246{
247 cpumask_set_cpu(cpu, cp->free_cpus);
248}
249
250/*
251 * cpudl_clear_freecpu - Clear the cpudl.free_cpus
252 * @cp: the cpudl max-heap context
253 * @cpu: rd attached CPU
254 */
255void cpudl_clear_freecpu(struct cpudl *cp, int cpu)
256{
257 cpumask_clear_cpu(cpu, cp->free_cpus);
258}
259
260/*
261 * cpudl_init - initialize the cpudl structure
262 * @cp: the cpudl max-heap context
263 */
264int cpudl_init(struct cpudl *cp)
265{
266 int i;
267
268 raw_spin_lock_init(&cp->lock);
269 cp->size = 0;
270
271 cp->elements = kcalloc(nr_cpu_ids,
272 sizeof(struct cpudl_item),
273 GFP_KERNEL);
274 if (!cp->elements)
275 return -ENOMEM;
276
277 if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
278 kfree(cp->elements);
279 return -ENOMEM;
280 }
281
282 for_each_possible_cpu(i)
283 cp->elements[i].idx = IDX_INVALID;
284
285 return 0;
286}
287
288/*
289 * cpudl_cleanup - clean up the cpudl structure
290 * @cp: the cpudl max-heap context
291 */
292void cpudl_cleanup(struct cpudl *cp)
293{
294 free_cpumask_var(cp->free_cpus);
295 kfree(cp->elements);
296}