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_allowed)) { 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_allowed) && 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 */ 150 void 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 */ 190 void 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 */ 221 void 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 */ 231 void 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 */ 240 int 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 */ 268 void cpudl_cleanup(struct cpudl *cp) 269 { 270 free_cpumask_var(cp->free_cpus); 271 kfree(cp->elements); 272 } 273