* procedure also covers cpu hotplug.
*/
int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;
+#ifdef CONFIG_NO_HZ_FULL
+/*
+ * tick_do_timer_boot_cpu indicates the boot CPU temporarily owns
+ * tick_do_timer_cpu and it should be taken over by an eligible secondary
+ * when one comes online.
+ */
+static int tick_do_timer_boot_cpu __read_mostly = -1;
+#endif
/*
* Debugging: see timer_list.c
!tick_broadcast_oneshot_active()) {
clockevents_switch_state(dev, CLOCK_EVT_STATE_PERIODIC);
} else {
- unsigned long seq;
+ unsigned int seq;
ktime_t next;
do {
}
}
+#ifdef CONFIG_NO_HZ_FULL
+static void giveup_do_timer(void *info)
+{
+ int cpu = *(unsigned int *)info;
+
+ WARN_ON(tick_do_timer_cpu != smp_processor_id());
+
+ tick_do_timer_cpu = cpu;
+}
+
+static void tick_take_do_timer_from_boot(void)
+{
+ int cpu = smp_processor_id();
+ int from = tick_do_timer_boot_cpu;
+
+ if (from >= 0 && from != cpu)
+ smp_call_function_single(from, giveup_do_timer, &cpu, 1);
+}
+#endif
+
/*
* Setup the tick device
*/
* this cpu:
*/
if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
- if (!tick_nohz_full_cpu(cpu))
- tick_do_timer_cpu = cpu;
- else
- tick_do_timer_cpu = TICK_DO_TIMER_NONE;
+ tick_do_timer_cpu = cpu;
+
tick_next_period = ktime_get();
tick_period = NSEC_PER_SEC / HZ;
+#ifdef CONFIG_NO_HZ_FULL
+ /*
+ * The boot CPU may be nohz_full, in which case set
+ * tick_do_timer_boot_cpu so the first housekeeping
+ * secondary that comes up will take do_timer from
+ * us.
+ */
+ if (tick_nohz_full_cpu(cpu))
+ tick_do_timer_boot_cpu = cpu;
+
+ } else if (tick_do_timer_boot_cpu != -1 &&
+ !tick_nohz_full_cpu(cpu)) {
+ tick_take_do_timer_from_boot();
+ tick_do_timer_boot_cpu = -1;
+ WARN_ON(tick_do_timer_cpu != cpu);
+#endif
}
/*