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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/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 return 1;
125 } else {
126 int best_cpu = cpudl_maximum(cp);
127
128 WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
129
130 if (cpumask_test_cpu(best_cpu, p->cpus_ptr) &&
131 dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
132 if (later_mask)
133 cpumask_set_cpu(best_cpu, later_mask);
134
135 return 1;
136 }
137 }
138 return 0;
139}
140
141/*
142 * cpudl_clear - remove a CPU from the cpudl max-heap
143 * @cp: the cpudl max-heap context
144 * @cpu: the target CPU
145 *
146 * Notes: assumes cpu_rq(cpu)->lock is locked
147 *
148 * Returns: (void)
149 */
150void cpudl_clear(struct cpudl *cp, int cpu)
151{
152 int old_idx, new_cpu;
153 unsigned long flags;
154
155 WARN_ON(!cpu_present(cpu));
156
157 raw_spin_lock_irqsave(&cp->lock, flags);
158
159 old_idx = cp->elements[cpu].idx;
160 if (old_idx == IDX_INVALID) {
161 /*
162 * Nothing to remove if old_idx was invalid.
163 * This could happen if a rq_offline_dl is
164 * called for a CPU without -dl tasks running.
165 */
166 } else {
167 new_cpu = cp->elements[cp->size - 1].cpu;
168 cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
169 cp->elements[old_idx].cpu = new_cpu;
170 cp->size--;
171 cp->elements[new_cpu].idx = old_idx;
172 cp->elements[cpu].idx = IDX_INVALID;
173 cpudl_heapify(cp, old_idx);
174
175 cpumask_set_cpu(cpu, cp->free_cpus);
176 }
177 raw_spin_unlock_irqrestore(&cp->lock, flags);
178}
179
180/*
181 * cpudl_set - update the cpudl max-heap
182 * @cp: the cpudl max-heap context
183 * @cpu: the target CPU
184 * @dl: the new earliest deadline for this CPU
185 *
186 * Notes: assumes cpu_rq(cpu)->lock is locked
187 *
188 * Returns: (void)
189 */
190void cpudl_set(struct cpudl *cp, int cpu, u64 dl)
191{
192 int old_idx;
193 unsigned long flags;
194
195 WARN_ON(!cpu_present(cpu));
196
197 raw_spin_lock_irqsave(&cp->lock, flags);
198
199 old_idx = cp->elements[cpu].idx;
200 if (old_idx == IDX_INVALID) {
201 int new_idx = cp->size++;
202
203 cp->elements[new_idx].dl = dl;
204 cp->elements[new_idx].cpu = cpu;
205 cp->elements[cpu].idx = new_idx;
206 cpudl_heapify_up(cp, new_idx);
207 cpumask_clear_cpu(cpu, cp->free_cpus);
208 } else {
209 cp->elements[old_idx].dl = dl;
210 cpudl_heapify(cp, old_idx);
211 }
212
213 raw_spin_unlock_irqrestore(&cp->lock, flags);
214}
215
216/*
217 * cpudl_set_freecpu - Set the cpudl.free_cpus
218 * @cp: the cpudl max-heap context
219 * @cpu: rd attached CPU
220 */
221void cpudl_set_freecpu(struct cpudl *cp, int cpu)
222{
223 cpumask_set_cpu(cpu, cp->free_cpus);
224}
225
226/*
227 * cpudl_clear_freecpu - Clear the cpudl.free_cpus
228 * @cp: the cpudl max-heap context
229 * @cpu: rd attached CPU
230 */
231void cpudl_clear_freecpu(struct cpudl *cp, int cpu)
232{
233 cpumask_clear_cpu(cpu, cp->free_cpus);
234}
235
236/*
237 * cpudl_init - initialize the cpudl structure
238 * @cp: the cpudl max-heap context
239 */
240int cpudl_init(struct cpudl *cp)
241{
242 int i;
243
244 raw_spin_lock_init(&cp->lock);
245 cp->size = 0;
246
247 cp->elements = kcalloc(nr_cpu_ids,
248 sizeof(struct cpudl_item),
249 GFP_KERNEL);
250 if (!cp->elements)
251 return -ENOMEM;
252
253 if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
254 kfree(cp->elements);
255 return -ENOMEM;
256 }
257
258 for_each_possible_cpu(i)
259 cp->elements[i].idx = IDX_INVALID;
260
261 return 0;
262}
263
264/*
265 * cpudl_cleanup - clean up the cpudl structure
266 * @cp: the cpudl max-heap context
267 */
268void cpudl_cleanup(struct cpudl *cp)
269{
270 free_cpumask_var(cp->free_cpus);
271 kfree(cp->elements);
272}