/*
* The idle thread. There's no useful work to be
* done, so just try to conserve power and have a
* low exit latency (ie sit in a loop waiting for
* somebody to say that they'd like to reschedule)
*/
void cpu_idle(void)
{
int cpu = smp_processor_id();
current_thread_info()->status |= TS_POLLING;
/* endless idle loop with no priority at all */
while (1) {
tick_nohz_stop_sched_tick();
while (!need_resched()) {
check_pgt_cache();
rmb();
if (rcu_pending(cpu))
rcu_check_callbacks(cpu, 0);
if (cpu_is_offline(cpu))
play_dead();
local_irq_disable();
__get_cpu_var(irq_stat).idle_timestamp = jiffies;
/* Don't trace irqs off for idle */
stop_critical_timings();
pm_idle();
start_critical_timings();
}
tick_nohz_restart_sched_tick();
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
asmlinkage void do_softirq(void)
{
unsigned int i, cpu;
unsigned long pending;
for ( ; ; )
{
/*
* Initialise @cpu on every iteration: SCHEDULE_SOFTIRQ may move
* us to another processor.
*/
cpu = smp_processor_id();
if ( rcu_pending(cpu) )
rcu_check_callbacks(cpu);
if ( (pending = softirq_pending(cpu)) == 0 )
break;
i = find_first_set_bit(pending);
clear_bit(i, &softirq_pending(cpu));
(*softirq_handlers[i])();
}
}
static unsigned long
consider_steal_time(unsigned long new_itm)
{
unsigned long stolen, blocked;
unsigned long delta_itm = 0, stolentick = 0;
int cpu = smp_processor_id();
struct vcpu_runstate_info runstate;
struct task_struct *p = current;
get_runstate_snapshot(&runstate);
/*
* Check for vcpu migration effect
* In this case, itc value is reversed.
* This causes huge stolen value.
* This function just checks and reject this effect.
*/
if (!time_after_eq(runstate.time[RUNSTATE_blocked],
per_cpu(xen_blocked_time, cpu)))
blocked = 0;
if (!time_after_eq(runstate.time[RUNSTATE_runnable] +
runstate.time[RUNSTATE_offline],
per_cpu(xen_stolen_time, cpu)))
stolen = 0;
if (!time_after(delta_itm + new_itm, ia64_get_itc()))
stolentick = ia64_get_itc() - new_itm;
do_div(stolentick, NS_PER_TICK);
stolentick++;
do_div(stolen, NS_PER_TICK);
if (stolen > stolentick)
stolen = stolentick;
stolentick -= stolen;
do_div(blocked, NS_PER_TICK);
if (blocked > stolentick)
blocked = stolentick;
if (stolen > 0 || blocked > 0) {
account_steal_ticks(stolen);
account_idle_ticks(blocked);
run_local_timers();
rcu_check_callbacks(cpu, user_mode(get_irq_regs()));
scheduler_tick();
run_posix_cpu_timers(p);
delta_itm += local_cpu_data->itm_delta * (stolen + blocked);
if (cpu == time_keeper_id)
xtime_update(stolen + blocked);
local_cpu_data->itm_next = delta_itm + new_itm;
per_cpu(xen_stolen_time, cpu) += NS_PER_TICK * stolen;
per_cpu(xen_blocked_time, cpu) += NS_PER_TICK * blocked;
}
return delta_itm;
}
