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(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(idx); 40 r = right_child(idx); 41 largest = idx; 42 largest_dl = orig_dl; 43 44 if ((l < cp->size) && dl_time_before(orig_dl, 45 cp->elements[l].dl)) { 46 largest = l; 47 largest_dl = cp->elements[l].dl; 48 } 49 if ((r < cp->size) && dl_time_before(largest_dl, 50 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(idx); 80 if (dl_time_before(orig_dl, 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(cp->elements[parent(idx)].dl, 97 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(later_mask, cp->free_cpus, &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, later_mask); 133 134 cap = capacity_orig_of(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(later_mask)) 145 cpumask_set_cpu(max_cpu, 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(best_cpu, &p->cpus_mask) && 154 dl_time_before(dl_se->deadline, cp->elements[0].dl)) { 155 if (later_mask) 156 cpumask_set_cpu(best_cpu, 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, old_idx); 197 198 cpumask_set_cpu(cpu, 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, new_idx); 230 cpumask_clear_cpu(cpu, cp->free_cpus); 231 } else { 232 cp->elements[old_idx].dl = dl; 233 cpudl_heapify(cp, 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, 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, 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(nr_cpu_ids, 271 sizeof(struct cpudl_item), 272 GFP_KERNEL); 273 if (!cp->elements) 274 return -ENOMEM; 275 276 if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) { 277 kfree(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(cp->free_cpus); 294 kfree(cp->elements); 295 } 296