-
- cpu_set(cpu, nohz_cpu_mask);
-
- /*
- * Leave the clock comparator set up for the next timer
- * tick if either rcu or a softirq is pending.
- */
- if (rcu_needs_cpu(cpu) || local_softirq_pending()) {
- cpu_clear(cpu, nohz_cpu_mask);
- return;
- }
-
- /*
- * This cpu is going really idle. Set up the clock comparator
- * for the next event.
- */
- next = next_timer_interrupt();
- do {
- seq = read_seqbegin_irqsave(&xtime_lock, flags);
- timer = ((__u64) next) - ((__u64) jiffies) + jiffies_64;
- } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
- todval = -1ULL;
- /* Be careful about overflows. */
- if (timer < (-1ULL / CLK_TICKS_PER_JIFFY)) {
- timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY;
- if (timer >= jiffies_timer_cc)
- todval = timer;
- }
- set_clock_comparator(todval);
-}
-
-/*
- * Start the HZ tick on the current CPU.
- * Only cpu_idle may call this function.
- */
-static void start_hz_timer(void)
-{
- BUG_ON(!in_interrupt());
-
- if (!cpu_isset(smp_processor_id(), nohz_cpu_mask))
- return;
- account_ticks(get_clock());
- set_clock_comparator(S390_lowcore.jiffy_timer + CPU_DEVIATION);
- cpu_clear(smp_processor_id(), nohz_cpu_mask);
-}
-
-static int nohz_idle_notify(struct notifier_block *self,
- unsigned long action, void *hcpu)
-{
- switch (action) {
- case S390_CPU_IDLE:
- stop_hz_timer();
- break;
- case S390_CPU_NOT_IDLE:
- start_hz_timer();
- break;
- }
- return NOTIFY_OK;