/* * 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; }