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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_heapify_down(struct cpudl *cp, int idx)
35{
36 int l, r, largest;
37
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
44 /* adapted from lib/prio_heap.c */
45 while(1) {
46 u64 largest_dl;
47 l = left_child(idx);
48 r = right_child(idx);
49 largest = idx;
50 largest_dl = orig_dl;
51
52 if ((l < cp->size) && dl_time_before(orig_dl,
53 cp->elements[l].dl)) {
54 largest = l;
55 largest_dl = cp->elements[l].dl;
56 }
57 if ((r < cp->size) && dl_time_before(largest_dl,
58 cp->elements[r].dl))
59 largest = r;
60
61 if (largest == idx)
62 break;
63
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;
68 idx = largest;
69 }
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;
74}
75
76static void cpudl_heapify_up(struct cpudl *cp, int idx)
77{
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;
100}
101
102static 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
111static 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 */
124int 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
130 if (later_mask &&
131 cpumask_and(later_mask, cp->free_cpus, tsk_cpus_allowed(p))) {
132 best_cpu = cpumask_any(later_mask);
133 goto out;
134 } else if (cpumask_test_cpu(cpudl_maximum(cp), tsk_cpus_allowed(p)) &&
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
141out:
142 WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
143
144 return best_cpu;
145}
146
147/*
148 * cpudl_clear - remove a cpu from the cpudl max-heap
149 * @cp: the cpudl max-heap context
150 * @cpu: the target cpu
151 *
152 * Notes: assumes cpu_rq(cpu)->lock is locked
153 *
154 * Returns: (void)
155 */
156void cpudl_clear(struct cpudl *cp, int cpu)
157{
158 int old_idx, new_cpu;
159 unsigned long flags;
160
161 WARN_ON(!cpu_present(cpu));
162
163 raw_spin_lock_irqsave(&cp->lock, flags);
164
165 old_idx = cp->elements[cpu].idx;
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 {
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--;
177 cp->elements[new_cpu].idx = old_idx;
178 cp->elements[cpu].idx = IDX_INVALID;
179 cpudl_heapify(cp, old_idx);
180
181 cpumask_set_cpu(cpu, cp->free_cpus);
182 }
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 */
196void 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));
202
203 raw_spin_lock_irqsave(&cp->lock, flags);
204
205 old_idx = cp->elements[cpu].idx;
206 if (old_idx == IDX_INVALID) {
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);
212 cpumask_clear_cpu(cpu, cp->free_cpus);
213 } else {
214 cp->elements[old_idx].dl = dl;
215 cpudl_heapify(cp, old_idx);
216 }
217
218 raw_spin_unlock_irqrestore(&cp->lock, flags);
219}
220
221/*
222 * cpudl_set_freecpu - Set the cpudl.free_cpus
223 * @cp: the cpudl max-heap context
224 * @cpu: rd attached cpu
225 */
226void 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 */
236void cpudl_clear_freecpu(struct cpudl *cp, int cpu)
237{
238 cpumask_clear_cpu(cpu, cp->free_cpus);
239}
240
241/*
242 * cpudl_init - initialize the cpudl structure
243 * @cp: the cpudl max-heap context
244 */
245int 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;
252
253 cp->elements = kcalloc(nr_cpu_ids,
254 sizeof(struct cpudl_item),
255 GFP_KERNEL);
256 if (!cp->elements)
257 return -ENOMEM;
258
259 if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
260 kfree(cp->elements);
261 return -ENOMEM;
262 }
263
264 for_each_possible_cpu(i)
265 cp->elements[i].idx = IDX_INVALID;
266
267 return 0;
268}
269
270/*
271 * cpudl_cleanup - clean up the cpudl structure
272 * @cp: the cpudl max-heap context
273 */
274void cpudl_cleanup(struct cpudl *cp)
275{
276 free_cpumask_var(cp->free_cpus);
277 kfree(cp->elements);
278}
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}