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 14 #include <linux/gfp.h> 15 #include <linux/kernel.h> 16 #include <linux/slab.h> 17 #include "cpudeadline.h" 18 19 static inline int parent(int i) 20 { 21 return (i - 1) >> 1; 22 } 23 24 static inline int left_child(int i) 25 { 26 return (i << 1) + 1; 27 } 28 29 static inline int right_child(int i) 30 { 31 return (i << 1) + 2; 32 } 33 34 static void cpudl_heapify_down(struct cpudl *cp, int idx) 35 { 36 int l, r, largest; 37 38 int orig_cpu = cp->elements[idx].cpu; 39 u64 orig_dl = cp->elements[idx].dl; 40 41 if (left_child(idx) >= cp->size) 42 return; 43 44 /* adapted from lib/prio_heap.c */ 45 while(1) { 46 u64 largest_dl; 47 l = left_child(idx); 48 r = right_child(idx); 49 largest = idx; 50 largest_dl = orig_dl; 51 52 if ((l < cp->size) && dl_time_before(orig_dl, 53 cp->elements[l].dl)) { 54 largest = l; 55 largest_dl = cp->elements[l].dl; 56 } 57 if ((r < cp->size) && dl_time_before(largest_dl, 58 cp->elements[r].dl)) 59 largest = r; 60 61 if (largest == idx) 62 break; 63 64 /* pull largest child onto idx */ 65 cp->elements[idx].cpu = cp->elements[largest].cpu; 66 cp->elements[idx].dl = cp->elements[largest].dl; 67 cp->elements[cp->elements[idx].cpu].idx = idx; 68 idx = largest; 69 } 70 /* actual push down of saved original values orig_* */ 71 cp->elements[idx].cpu = orig_cpu; 72 cp->elements[idx].dl = orig_dl; 73 cp->elements[cp->elements[idx].cpu].idx = idx; 74 } 75 76 static void cpudl_heapify_up(struct cpudl *cp, int idx) 77 { 78 int p; 79 80 int orig_cpu = cp->elements[idx].cpu; 81 u64 orig_dl = cp->elements[idx].dl; 82 83 if (idx == 0) 84 return; 85 86 do { 87 p = parent(idx); 88 if (dl_time_before(orig_dl, cp->elements[p].dl)) 89 break; 90 /* pull parent onto idx */ 91 cp->elements[idx].cpu = cp->elements[p].cpu; 92 cp->elements[idx].dl = cp->elements[p].dl; 93 cp->elements[cp->elements[idx].cpu].idx = idx; 94 idx = p; 95 } while (idx != 0); 96 /* actual push up of saved original values orig_* */ 97 cp->elements[idx].cpu = orig_cpu; 98 cp->elements[idx].dl = orig_dl; 99 cp->elements[cp->elements[idx].cpu].idx = idx; 100 } 101 102 static void cpudl_heapify(struct cpudl *cp, int idx) 103 { 104 if (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl, 105 cp->elements[idx].dl)) 106 cpudl_heapify_up(cp, idx); 107 else 108 cpudl_heapify_down(cp, idx); 109 } 110 111 static inline int cpudl_maximum(struct cpudl *cp) 112 { 113 return cp->elements[0].cpu; 114 } 115 116 /* 117 * cpudl_find - find the best (later-dl) CPU in the system 118 * @cp: the cpudl max-heap context 119 * @p: the task 120 * @later_mask: a mask to fill in with the selected CPUs (or NULL) 121 * 122 * Returns: int - best CPU (heap maximum if suitable) 123 */ 124 int cpudl_find(struct cpudl *cp, struct task_struct *p, 125 struct cpumask *later_mask) 126 { 127 int best_cpu = -1; 128 const struct sched_dl_entity *dl_se = &p->dl; 129 130 if (later_mask && 131 cpumask_and(later_mask, cp->free_cpus, &p->cpus_allowed)) { 132 best_cpu = cpumask_any(later_mask); 133 goto out; 134 } else if (cpumask_test_cpu(cpudl_maximum(cp), &p->cpus_allowed) && 135 dl_time_before(dl_se->deadline, cp->elements[0].dl)) { 136 best_cpu = cpudl_maximum(cp); 137 if (later_mask) 138 cpumask_set_cpu(best_cpu, later_mask); 139 } 140 141 out: 142 WARN_ON(best_cpu != -1 && !cpu_present(best_cpu)); 143 144 return best_cpu; 145 } 146 147 /* 148 * cpudl_clear - remove a cpu from the cpudl max-heap 149 * @cp: the cpudl max-heap context 150 * @cpu: the target cpu 151 * 152 * Notes: assumes cpu_rq(cpu)->lock is locked 153 * 154 * Returns: (void) 155 */ 156 void cpudl_clear(struct cpudl *cp, int cpu) 157 { 158 int old_idx, new_cpu; 159 unsigned long flags; 160 161 WARN_ON(!cpu_present(cpu)); 162 163 raw_spin_lock_irqsave(&cp->lock, flags); 164 165 old_idx = cp->elements[cpu].idx; 166 if (old_idx == IDX_INVALID) { 167 /* 168 * Nothing to remove if old_idx was invalid. 169 * This could happen if a rq_offline_dl is 170 * called for a CPU without -dl tasks running. 171 */ 172 } else { 173 new_cpu = cp->elements[cp->size - 1].cpu; 174 cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl; 175 cp->elements[old_idx].cpu = new_cpu; 176 cp->size--; 177 cp->elements[new_cpu].idx = old_idx; 178 cp->elements[cpu].idx = IDX_INVALID; 179 cpudl_heapify(cp, old_idx); 180 181 cpumask_set_cpu(cpu, cp->free_cpus); 182 } 183 raw_spin_unlock_irqrestore(&cp->lock, flags); 184 } 185 186 /* 187 * cpudl_set - update the cpudl max-heap 188 * @cp: the cpudl max-heap context 189 * @cpu: the target cpu 190 * @dl: the new earliest deadline for this cpu 191 * 192 * Notes: assumes cpu_rq(cpu)->lock is locked 193 * 194 * Returns: (void) 195 */ 196 void cpudl_set(struct cpudl *cp, int cpu, u64 dl) 197 { 198 int old_idx; 199 unsigned long flags; 200 201 WARN_ON(!cpu_present(cpu)); 202 203 raw_spin_lock_irqsave(&cp->lock, flags); 204 205 old_idx = cp->elements[cpu].idx; 206 if (old_idx == IDX_INVALID) { 207 int new_idx = cp->size++; 208 cp->elements[new_idx].dl = dl; 209 cp->elements[new_idx].cpu = cpu; 210 cp->elements[cpu].idx = new_idx; 211 cpudl_heapify_up(cp, new_idx); 212 cpumask_clear_cpu(cpu, cp->free_cpus); 213 } else { 214 cp->elements[old_idx].dl = dl; 215 cpudl_heapify(cp, old_idx); 216 } 217 218 raw_spin_unlock_irqrestore(&cp->lock, flags); 219 } 220 221 /* 222 * cpudl_set_freecpu - Set the cpudl.free_cpus 223 * @cp: the cpudl max-heap context 224 * @cpu: rd attached cpu 225 */ 226 void cpudl_set_freecpu(struct cpudl *cp, int cpu) 227 { 228 cpumask_set_cpu(cpu, cp->free_cpus); 229 } 230 231 /* 232 * cpudl_clear_freecpu - Clear the cpudl.free_cpus 233 * @cp: the cpudl max-heap context 234 * @cpu: rd attached cpu 235 */ 236 void cpudl_clear_freecpu(struct cpudl *cp, int cpu) 237 { 238 cpumask_clear_cpu(cpu, cp->free_cpus); 239 } 240 241 /* 242 * cpudl_init - initialize the cpudl structure 243 * @cp: the cpudl max-heap context 244 */ 245 int cpudl_init(struct cpudl *cp) 246 { 247 int i; 248 249 memset(cp, 0, sizeof(*cp)); 250 raw_spin_lock_init(&cp->lock); 251 cp->size = 0; 252 253 cp->elements = kcalloc(nr_cpu_ids, 254 sizeof(struct cpudl_item), 255 GFP_KERNEL); 256 if (!cp->elements) 257 return -ENOMEM; 258 259 if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) { 260 kfree(cp->elements); 261 return -ENOMEM; 262 } 263 264 for_each_possible_cpu(i) 265 cp->elements[i].idx = IDX_INVALID; 266 267 return 0; 268 } 269 270 /* 271 * cpudl_cleanup - clean up the cpudl structure 272 * @cp: the cpudl max-heap context 273 */ 274 void cpudl_cleanup(struct cpudl *cp) 275 { 276 free_cpumask_var(cp->free_cpus); 277 kfree(cp->elements); 278 } 279