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 | |
10 | static inline int parent(int i) |
11 | { |
12 | return (i - 1) >> 1; |
13 | } |
14 | |
15 | static inline int left_child(int i) |
16 | { |
17 | return (i << 1) + 1; |
18 | } |
19 | |
20 | static inline int right_child(int i) |
21 | { |
22 | return (i << 1) + 2; |
23 | } |
24 | |
25 | static 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(i: 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(i: idx); |
40 | r = right_child(i: idx); |
41 | largest = idx; |
42 | largest_dl = orig_dl; |
43 | |
44 | if ((l < cp->size) && dl_time_before(a: orig_dl, |
45 | b: cp->elements[l].dl)) { |
46 | largest = l; |
47 | largest_dl = cp->elements[l].dl; |
48 | } |
49 | if ((r < cp->size) && dl_time_before(a: largest_dl, |
50 | b: 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 | |
68 | static 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(i: idx); |
80 | if (dl_time_before(a: orig_dl, b: 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 | |
94 | static void cpudl_heapify(struct cpudl *cp, int idx) |
95 | { |
96 | if (idx > 0 && dl_time_before(a: cp->elements[parent(i: idx)].dl, |
97 | b: cp->elements[idx].dl)) |
98 | cpudl_heapify_up(cp, idx); |
99 | else |
100 | cpudl_heapify_down(cp, idx); |
101 | } |
102 | |
103 | static 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 | */ |
116 | int 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(dstp: later_mask, src1p: cp->free_cpus, src2p: &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, dstp: 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(srcp: later_mask)) |
145 | cpumask_set_cpu(cpu: max_cpu, dstp: 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(cpu: best_cpu, cpumask: &p->cpus_mask) && |
154 | dl_time_before(a: dl_se->deadline, b: cp->elements[0].dl)) { |
155 | if (later_mask) |
156 | cpumask_set_cpu(cpu: best_cpu, dstp: 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 | */ |
173 | void 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, idx: old_idx); |
197 | |
198 | cpumask_set_cpu(cpu, dstp: 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 | */ |
213 | void 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, idx: new_idx); |
230 | cpumask_clear_cpu(cpu, dstp: cp->free_cpus); |
231 | } else { |
232 | cp->elements[old_idx].dl = dl; |
233 | cpudl_heapify(cp, idx: 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 | */ |
244 | void cpudl_set_freecpu(struct cpudl *cp, int cpu) |
245 | { |
246 | cpumask_set_cpu(cpu, dstp: 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 | */ |
254 | void cpudl_clear_freecpu(struct cpudl *cp, int cpu) |
255 | { |
256 | cpumask_clear_cpu(cpu, dstp: cp->free_cpus); |
257 | } |
258 | |
259 | /* |
260 | * cpudl_init - initialize the cpudl structure |
261 | * @cp: the cpudl max-heap context |
262 | */ |
263 | int 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(n: nr_cpu_ids, |
271 | size: sizeof(struct cpudl_item), |
272 | GFP_KERNEL); |
273 | if (!cp->elements) |
274 | return -ENOMEM; |
275 | |
276 | if (!zalloc_cpumask_var(mask: &cp->free_cpus, GFP_KERNEL)) { |
277 | kfree(objp: 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 | */ |
291 | void cpudl_cleanup(struct cpudl *cp) |
292 | { |
293 | free_cpumask_var(mask: cp->free_cpus); |
294 | kfree(objp: cp->elements); |
295 | } |
296 | |