4 * Global CPU deadline management
6 * Author: Juri Lelli <j.lelli@sssup.it>
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
14 #include <linux/gfp.h>
15 #include <linux/kernel.h>
16 #include <linux/slab.h>
17 #include "cpudeadline.h"
19 static inline int parent(int i)
24 static inline int left_child(int i)
29 static inline int right_child(int i)
34 static inline int dl_time_before(u64 a, u64 b)
36 return (s64)(a - b) < 0;
39 static void cpudl_exchange(struct cpudl *cp, int a, int b)
41 int cpu_a = cp->elements[a].cpu, cpu_b = cp->elements[b].cpu;
43 swap(cp->elements[a].cpu, cp->elements[b].cpu);
44 swap(cp->elements[a].dl , cp->elements[b].dl );
46 swap(cp->elements[cpu_a].idx, cp->elements[cpu_b].idx);
49 static void cpudl_heapify(struct cpudl *cp, int idx)
53 /* adapted from lib/prio_heap.c */
59 if ((l < cp->size) && dl_time_before(cp->elements[idx].dl,
62 if ((r < cp->size) && dl_time_before(cp->elements[largest].dl,
68 /* Push idx down the heap one level and bump one up */
69 cpudl_exchange(cp, largest, idx);
74 static void cpudl_change_key(struct cpudl *cp, int idx, u64 new_dl)
76 WARN_ON(idx == IDX_INVALID || !cpu_present(idx));
78 if (dl_time_before(new_dl, cp->elements[idx].dl)) {
79 cp->elements[idx].dl = new_dl;
80 cpudl_heapify(cp, idx);
82 cp->elements[idx].dl = new_dl;
83 while (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
84 cp->elements[idx].dl)) {
85 cpudl_exchange(cp, idx, parent(idx));
91 static inline int cpudl_maximum(struct cpudl *cp)
93 return cp->elements[0].cpu;
97 * cpudl_find - find the best (later-dl) CPU in the system
98 * @cp: the cpudl max-heap context
100 * @later_mask: a mask to fill in with the selected CPUs (or NULL)
102 * Returns: int - best CPU (heap maximum if suitable)
104 int cpudl_find(struct cpudl *cp, struct task_struct *p,
105 struct cpumask *later_mask)
108 const struct sched_dl_entity *dl_se = &p->dl;
110 if (later_mask && cpumask_and(later_mask, cp->free_cpus,
111 &p->cpus_allowed) && cpumask_and(later_mask,
112 later_mask, cpu_active_mask)) {
113 best_cpu = cpumask_any(later_mask);
115 } else if (cpumask_test_cpu(cpudl_maximum(cp), &p->cpus_allowed) &&
116 dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
117 best_cpu = cpudl_maximum(cp);
119 cpumask_set_cpu(best_cpu, later_mask);
123 WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
129 * cpudl_set - update the cpudl max-heap
130 * @cp: the cpudl max-heap context
131 * @cpu: the target cpu
132 * @dl: the new earliest deadline for this cpu
134 * Notes: assumes cpu_rq(cpu)->lock is locked
138 void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
140 int old_idx, new_cpu;
143 WARN_ON(!cpu_present(cpu));
145 raw_spin_lock_irqsave(&cp->lock, flags);
146 old_idx = cp->elements[cpu].idx;
149 if (old_idx == IDX_INVALID) {
151 * Nothing to remove if old_idx was invalid.
152 * This could happen if a rq_offline_dl is
153 * called for a CPU without -dl tasks running.
157 new_cpu = cp->elements[cp->size - 1].cpu;
158 cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
159 cp->elements[old_idx].cpu = new_cpu;
161 cp->elements[new_cpu].idx = old_idx;
162 cp->elements[cpu].idx = IDX_INVALID;
163 while (old_idx > 0 && dl_time_before(
164 cp->elements[parent(old_idx)].dl,
165 cp->elements[old_idx].dl)) {
166 cpudl_exchange(cp, old_idx, parent(old_idx));
167 old_idx = parent(old_idx);
169 cpumask_set_cpu(cpu, cp->free_cpus);
170 cpudl_heapify(cp, old_idx);
175 if (old_idx == IDX_INVALID) {
177 cp->elements[cp->size - 1].dl = 0;
178 cp->elements[cp->size - 1].cpu = cpu;
179 cp->elements[cpu].idx = cp->size - 1;
180 cpudl_change_key(cp, cp->size - 1, dl);
181 cpumask_clear_cpu(cpu, cp->free_cpus);
183 cpudl_change_key(cp, old_idx, dl);
187 raw_spin_unlock_irqrestore(&cp->lock, flags);
191 * cpudl_init - initialize the cpudl structure
192 * @cp: the cpudl max-heap context
194 int cpudl_init(struct cpudl *cp)
198 memset(cp, 0, sizeof(*cp));
199 raw_spin_lock_init(&cp->lock);
202 cp->elements = kcalloc(nr_cpu_ids,
203 sizeof(struct cpudl_item),
208 if (!alloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
213 for_each_possible_cpu(i)
214 cp->elements[i].idx = IDX_INVALID;
216 cpumask_setall(cp->free_cpus);
222 * cpudl_cleanup - clean up the cpudl structure
223 * @cp: the cpudl max-heap context
225 void cpudl_cleanup(struct cpudl *cp)
227 free_cpumask_var(cp->free_cpus);