/*
* Get the preferred target CPU for NOHZ
*/
static int hrtimer_get_target(int this_cpu, int pinned)
{
#ifdef CONFIG_NO_HZ
if (!pinned && get_sysctl_timer_migration() && idle_cpu(this_cpu))
return get_nohz_timer_target();
#endif
return this_cpu;
}
static inline
struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
int pinned)
{
if (pinned || !base->migration_enabled)
return base;
return &per_cpu(hrtimer_bases, get_nohz_timer_target());
}
/*
* Switch the timer base to the current CPU when possible.
*/
static inline struct hrtimer_clock_base *
switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
int pinned)
{
struct hrtimer_clock_base *new_base;
struct hrtimer_cpu_base *new_cpu_base;
int this_cpu = smp_processor_id();
int cpu = get_nohz_timer_target(pinned);
int basenum = base->index;
again:
new_cpu_base = &per_cpu(hrtimer_bases, cpu);
new_base = &new_cpu_base->clock_base[basenum];
if (base != new_base) {
/*
* We are trying to move timer to new_base.
* However we can't change timer's base while it is running,
* so we keep it on the same CPU. No hassle vs. reprogramming
* the event source in the high resolution case. The softirq
* code will take care of this when the timer function has
* completed. There is no conflict as we hold the lock until
* the timer is enqueued.
*/
if (unlikely(hrtimer_callback_running(timer)))
return base;
/* See the comment in lock_timer_base() */
timer->base = NULL;
raw_spin_unlock(&base->cpu_base->lock);
raw_spin_lock(&new_base->cpu_base->lock);
if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
cpu = this_cpu;
raw_spin_unlock(&new_base->cpu_base->lock);
raw_spin_lock(&base->cpu_base->lock);
timer->base = base;
goto again;
}
timer->base = new_base;
} else {
if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
cpu = this_cpu;
goto again;
}
}
return new_base;
}
/*
* Get the preferred target CPU for NOHZ
*/
static int hrtimer_get_target(int this_cpu, int pinned)
{
#ifdef CONFIG_NO_HZ
#ifdef CONFIG_SCHED_BFS
if (!pinned && get_sysctl_timer_migration() && idle_cpu(this_cpu)) {
int preferred_cpu = get_nohz_load_balancer();
if (preferred_cpu >= 0)
return preferred_cpu;
}
#else
if (!pinned && get_sysctl_timer_migration() && idle_cpu(this_cpu))
return get_nohz_timer_target();
#endif
#endif
return this_cpu;
}