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 11 static inline int parent(int i) 12 { 13 return (i - 1) >> 1; 14 } 15 16 static inline int left_child(int i) 17 { 18 return (i << 1) + 1; 19 } 20 21 static inline int right_child(int i) 22 { 23 return (i << 1) + 2; 24 } 25 26 static 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 69 static 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 95 static 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 } 103 104 static 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 */ 117 int 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 */ 174 void 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 */ 214 void 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 */ 245 void 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 */ 255 void 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 */ 264 int 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 */ 292 void cpudl_cleanup(struct cpudl *cp) 293 { 294 free_cpumask_var(cp->free_cpus); 295 kfree(cp->elements); 296 } 297