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/*
* kernel/sched/cpudl.c
*
* Global CPU deadline management
*
* Author: Juri Lelli <j.lelli@sssup.it>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; version 2
* of the License.
*/
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include "cpudeadline.h"
static inline int parent(int i)
{
return (i - 1) >> 1;
}
static inline int left_child(int i)
{
return (i << 1) + 1;
}
static inline int right_child(int i)
{
return (i << 1) + 2;
}
static void cpudl_heapify_down(struct cpudl *cp, int idx)
{
int l, r, largest;
int orig_cpu = cp->elements[idx].cpu;
u64 orig_dl = cp->elements[idx].dl;
if (left_child(idx) >= cp->size)
return;
/* adapted from lib/prio_heap.c */
while(1) {
u64 largest_dl;
l = left_child(idx);
r = right_child(idx);
largest = idx;
largest_dl = orig_dl;
if ((l < cp->size) && dl_time_before(orig_dl,
cp->elements[l].dl)) {
largest = l;
largest_dl = cp->elements[l].dl;
}
if ((r < cp->size) && dl_time_before(largest_dl,
cp->elements[r].dl))
largest = r;
if (largest == idx)
break;
/* pull largest child onto idx */
cp->elements[idx].cpu = cp->elements[largest].cpu;
cp->elements[idx].dl = cp->elements[largest].dl;
cp->elements[cp->elements[idx].cpu].idx = idx;
idx = largest;
}
/* actual push down of saved original values orig_* */
cp->elements[idx].cpu = orig_cpu;
cp->elements[idx].dl = orig_dl;
cp->elements[cp->elements[idx].cpu].idx = idx;
}
static void cpudl_heapify_up(struct cpudl *cp, int idx)
{
int p;
int orig_cpu = cp->elements[idx].cpu;
u64 orig_dl = cp->elements[idx].dl;
if (idx == 0)
return;
do {
p = parent(idx);
if (dl_time_before(orig_dl, cp->elements[p].dl))
break;
/* pull parent onto idx */
cp->elements[idx].cpu = cp->elements[p].cpu;
cp->elements[idx].dl = cp->elements[p].dl;
cp->elements[cp->elements[idx].cpu].idx = idx;
idx = p;
} while (idx != 0);
/* actual push up of saved original values orig_* */
cp->elements[idx].cpu = orig_cpu;
cp->elements[idx].dl = orig_dl;
cp->elements[cp->elements[idx].cpu].idx = idx;
}
static void cpudl_heapify(struct cpudl *cp, int idx)
{
if (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
cp->elements[idx].dl))
cpudl_heapify_up(cp, idx);
else
cpudl_heapify_down(cp, idx);
}
static inline int cpudl_maximum(struct cpudl *cp)
{
return cp->elements[0].cpu;
}
/*
* cpudl_find - find the best (later-dl) CPU in the system
* @cp: the cpudl max-heap context
* @p: the task
* @later_mask: a mask to fill in with the selected CPUs (or NULL)
*
* Returns: int - best CPU (heap maximum if suitable)
*/
int cpudl_find(struct cpudl *cp, struct task_struct *p,
struct cpumask *later_mask)
{
int best_cpu = -1;
const struct sched_dl_entity *dl_se = &p->dl;
if (later_mask &&
cpumask_and(later_mask, cp->free_cpus, tsk_cpus_allowed(p))) {
best_cpu = cpumask_any(later_mask);
goto out;
} else if (cpumask_test_cpu(cpudl_maximum(cp), tsk_cpus_allowed(p)) &&
dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
best_cpu = cpudl_maximum(cp);
if (later_mask)
cpumask_set_cpu(best_cpu, later_mask);
}
out:
WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
return best_cpu;
}
/*
* cpudl_clear - remove a cpu from the cpudl max-heap
* @cp: the cpudl max-heap context
* @cpu: the target cpu
*
* Notes: assumes cpu_rq(cpu)->lock is locked
*
* Returns: (void)
*/
void cpudl_clear(struct cpudl *cp, int cpu)
{
int old_idx, new_cpu;
unsigned long flags;
WARN_ON(!cpu_present(cpu));
raw_spin_lock_irqsave(&cp->lock, flags);
old_idx = cp->elements[cpu].idx;
if (old_idx == IDX_INVALID) {
/*
* Nothing to remove if old_idx was invalid.
* This could happen if a rq_offline_dl is
* called for a CPU without -dl tasks running.
*/
} else {
new_cpu = cp->elements[cp->size - 1].cpu;
cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
cp->elements[old_idx].cpu = new_cpu;
cp->size--;
cp->elements[new_cpu].idx = old_idx;
cp->elements[cpu].idx = IDX_INVALID;
cpudl_heapify(cp, old_idx);
cpumask_set_cpu(cpu, cp->free_cpus);
}
raw_spin_unlock_irqrestore(&cp->lock, flags);
}
/*
* cpudl_set - update the cpudl max-heap
* @cp: the cpudl max-heap context
* @cpu: the target cpu
* @dl: the new earliest deadline for this cpu
*
* Notes: assumes cpu_rq(cpu)->lock is locked
*
* Returns: (void)
*/
void cpudl_set(struct cpudl *cp, int cpu, u64 dl)
{
int old_idx;
unsigned long flags;
WARN_ON(!cpu_present(cpu));
raw_spin_lock_irqsave(&cp->lock, flags);
old_idx = cp->elements[cpu].idx;
if (old_idx == IDX_INVALID) {
int new_idx = cp->size++;
cp->elements[new_idx].dl = dl;
cp->elements[new_idx].cpu = cpu;
cp->elements[cpu].idx = new_idx;
cpudl_heapify_up(cp, new_idx);
cpumask_clear_cpu(cpu, cp->free_cpus);
} else {
cp->elements[old_idx].dl = dl;
cpudl_heapify(cp, old_idx);
}
raw_spin_unlock_irqrestore(&cp->lock, flags);
}
/*
* cpudl_set_freecpu - Set the cpudl.free_cpus
* @cp: the cpudl max-heap context
* @cpu: rd attached cpu
*/
void cpudl_set_freecpu(struct cpudl *cp, int cpu)
{
cpumask_set_cpu(cpu, cp->free_cpus);
}
/*
* cpudl_clear_freecpu - Clear the cpudl.free_cpus
* @cp: the cpudl max-heap context
* @cpu: rd attached cpu
*/
void cpudl_clear_freecpu(struct cpudl *cp, int cpu)
{
cpumask_clear_cpu(cpu, cp->free_cpus);
}
/*
* cpudl_init - initialize the cpudl structure
* @cp: the cpudl max-heap context
*/
int cpudl_init(struct cpudl *cp)
{
int i;
memset(cp, 0, sizeof(*cp));
raw_spin_lock_init(&cp->lock);
cp->size = 0;
cp->elements = kcalloc(nr_cpu_ids,
sizeof(struct cpudl_item),
GFP_KERNEL);
if (!cp->elements)
return -ENOMEM;
if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
kfree(cp->elements);
return -ENOMEM;
}
for_each_possible_cpu(i)
cp->elements[i].idx = IDX_INVALID;
return 0;
}
/*
* cpudl_cleanup - clean up the cpudl structure
* @cp: the cpudl max-heap context
*/
void cpudl_cleanup(struct cpudl *cp)
{
free_cpumask_var(cp->free_cpus);
kfree(cp->elements);
}
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