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 #include "sched.h" 14 15 static inline int parent(int i) 16 { 17 return (i - 1) >> 1; 18 } 19 20 static inline int left_child(int i) 21 { 22 return (i << 1) + 1; 23 } 24 25 static inline int right_child(int i) 26 { 27 return (i << 1) + 2; 28 } 29 30 static void cpudl_heapify_down(struct cpudl *cp, int idx) 31 { 32 int l, r, largest; 33 34 int orig_cpu = cp->elements[idx].cpu; 35 u64 orig_dl = cp->elements[idx].dl; 36 37 if (left_child(idx) >= cp->size) 38 return; 39 40 /* adapted from lib/prio_heap.c */ 41 while (1) { 42 u64 largest_dl; 43 44 l = left_child(idx); 45 r = right_child(idx); 46 largest = idx; 47 largest_dl = orig_dl; 48 49 if ((l < cp->size) && dl_time_before(orig_dl, 50 cp->elements[l].dl)) { 51 largest = l; 52 largest_dl = cp->elements[l].dl; 53 } 54 if ((r < cp->size) && dl_time_before(largest_dl, 55 cp->elements[r].dl)) 56 largest = r; 57 58 if (largest == idx) 59 break; 60 61 /* pull largest child onto idx */ 62 cp->elements[idx].cpu = cp->elements[largest].cpu; 63 cp->elements[idx].dl = cp->elements[largest].dl; 64 cp->elements[cp->elements[idx].cpu].idx = idx; 65 idx = largest; 66 } 67 /* actual push down of saved original values orig_* */ 68 cp->elements[idx].cpu = orig_cpu; 69 cp->elements[idx].dl = orig_dl; 70 cp->elements[cp->elements[idx].cpu].idx = idx; 71 } 72 73 static void cpudl_heapify_up(struct cpudl *cp, int idx) 74 { 75 int p; 76 77 int orig_cpu = cp->elements[idx].cpu; 78 u64 orig_dl = cp->elements[idx].dl; 79 80 if (idx == 0) 81 return; 82 83 do { 84 p = parent(idx); 85 if (dl_time_before(orig_dl, cp->elements[p].dl)) 86 break; 87 /* pull parent onto idx */ 88 cp->elements[idx].cpu = cp->elements[p].cpu; 89 cp->elements[idx].dl = cp->elements[p].dl; 90 cp->elements[cp->elements[idx].cpu].idx = idx; 91 idx = p; 92 } while (idx != 0); 93 /* actual push up of saved original values orig_* */ 94 cp->elements[idx].cpu = orig_cpu; 95 cp->elements[idx].dl = orig_dl; 96 cp->elements[cp->elements[idx].cpu].idx = idx; 97 } 98 99 static void cpudl_heapify(struct cpudl *cp, int idx) 100 { 101 if (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl, 102 cp->elements[idx].dl)) 103 cpudl_heapify_up(cp, idx); 104 else 105 cpudl_heapify_down(cp, idx); 106 } 107 108 static inline int cpudl_maximum(struct cpudl *cp) 109 { 110 return cp->elements[0].cpu; 111 } 112 113 /* 114 * cpudl_find - find the best (later-dl) CPU in the system 115 * @cp: the cpudl max-heap context 116 * @p: the task 117 * @later_mask: a mask to fill in with the selected CPUs (or NULL) 118 * 119 * Returns: int - CPUs were found 120 */ 121 int cpudl_find(struct cpudl *cp, struct task_struct *p, 122 struct cpumask *later_mask) 123 { 124 const struct sched_dl_entity *dl_se = &p->dl; 125 126 if (later_mask && 127 cpumask_and(later_mask, cp->free_cpus, &p->cpus_allowed)) { 128 return 1; 129 } else { 130 int best_cpu = cpudl_maximum(cp); 131 132 WARN_ON(best_cpu != -1 && !cpu_present(best_cpu)); 133 134 if (cpumask_test_cpu(best_cpu, &p->cpus_allowed) && 135 dl_time_before(dl_se->deadline, cp->elements[0].dl)) { 136 if (later_mask) 137 cpumask_set_cpu(best_cpu, later_mask); 138 139 return 1; 140 } 141 } 142 return 0; 143 } 144 145 /* 146 * cpudl_clear - remove a CPU from the cpudl max-heap 147 * @cp: the cpudl max-heap context 148 * @cpu: the target CPU 149 * 150 * Notes: assumes cpu_rq(cpu)->lock is locked 151 * 152 * Returns: (void) 153 */ 154 void cpudl_clear(struct cpudl *cp, int cpu) 155 { 156 int old_idx, new_cpu; 157 unsigned long flags; 158 159 WARN_ON(!cpu_present(cpu)); 160 161 raw_spin_lock_irqsave(&cp->lock, flags); 162 163 old_idx = cp->elements[cpu].idx; 164 if (old_idx == IDX_INVALID) { 165 /* 166 * Nothing to remove if old_idx was invalid. 167 * This could happen if a rq_offline_dl is 168 * called for a CPU without -dl tasks running. 169 */ 170 } else { 171 new_cpu = cp->elements[cp->size - 1].cpu; 172 cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl; 173 cp->elements[old_idx].cpu = new_cpu; 174 cp->size--; 175 cp->elements[new_cpu].idx = old_idx; 176 cp->elements[cpu].idx = IDX_INVALID; 177 cpudl_heapify(cp, old_idx); 178 179 cpumask_set_cpu(cpu, cp->free_cpus); 180 } 181 raw_spin_unlock_irqrestore(&cp->lock, flags); 182 } 183 184 /* 185 * cpudl_set - update the cpudl max-heap 186 * @cp: the cpudl max-heap context 187 * @cpu: the target CPU 188 * @dl: the new earliest deadline for this CPU 189 * 190 * Notes: assumes cpu_rq(cpu)->lock is locked 191 * 192 * Returns: (void) 193 */ 194 void cpudl_set(struct cpudl *cp, int cpu, u64 dl) 195 { 196 int old_idx; 197 unsigned long flags; 198 199 WARN_ON(!cpu_present(cpu)); 200 201 raw_spin_lock_irqsave(&cp->lock, flags); 202 203 old_idx = cp->elements[cpu].idx; 204 if (old_idx == IDX_INVALID) { 205 int new_idx = cp->size++; 206 207 cp->elements[new_idx].dl = dl; 208 cp->elements[new_idx].cpu = cpu; 209 cp->elements[cpu].idx = new_idx; 210 cpudl_heapify_up(cp, new_idx); 211 cpumask_clear_cpu(cpu, cp->free_cpus); 212 } else { 213 cp->elements[old_idx].dl = dl; 214 cpudl_heapify(cp, old_idx); 215 } 216 217 raw_spin_unlock_irqrestore(&cp->lock, flags); 218 } 219 220 /* 221 * cpudl_set_freecpu - Set the cpudl.free_cpus 222 * @cp: the cpudl max-heap context 223 * @cpu: rd attached CPU 224 */ 225 void cpudl_set_freecpu(struct cpudl *cp, int cpu) 226 { 227 cpumask_set_cpu(cpu, cp->free_cpus); 228 } 229 230 /* 231 * cpudl_clear_freecpu - Clear the cpudl.free_cpus 232 * @cp: the cpudl max-heap context 233 * @cpu: rd attached CPU 234 */ 235 void cpudl_clear_freecpu(struct cpudl *cp, int cpu) 236 { 237 cpumask_clear_cpu(cpu, cp->free_cpus); 238 } 239 240 /* 241 * cpudl_init - initialize the cpudl structure 242 * @cp: the cpudl max-heap context 243 */ 244 int cpudl_init(struct cpudl *cp) 245 { 246 int i; 247 248 raw_spin_lock_init(&cp->lock); 249 cp->size = 0; 250 251 cp->elements = kcalloc(nr_cpu_ids, 252 sizeof(struct cpudl_item), 253 GFP_KERNEL); 254 if (!cp->elements) 255 return -ENOMEM; 256 257 if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) { 258 kfree(cp->elements); 259 return -ENOMEM; 260 } 261 262 for_each_possible_cpu(i) 263 cp->elements[i].idx = IDX_INVALID; 264 265 return 0; 266 } 267 268 /* 269 * cpudl_cleanup - clean up the cpudl structure 270 * @cp: the cpudl max-heap context 271 */ 272 void cpudl_cleanup(struct cpudl *cp) 273 { 274 free_cpumask_var(cp->free_cpus); 275 kfree(cp->elements); 276 } 277