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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/*
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}