clocksource: Cleanup clocksource selection
[linux-2.6.git] / kernel / time / tick-oneshot.c
index 450c049..a96c0e2 100644 (file)
 #include "tick-internal.h"
 
 /**
- * tick_program_event
+ * tick_program_event internal worker function
  */
-int tick_program_event(ktime_t expires, int force)
+int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
+                          int force)
 {
-       struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
        ktime_t now = ktime_get();
+       int i;
 
-       while (1) {
+       for (i = 0;;) {
                int ret = clockevents_program_event(dev, expires, now);
 
                if (!ret || !force)
                        return ret;
+
+               /*
+                * We tried 2 times to program the device with the given
+                * min_delta_ns. If that's not working then we double it
+                * and emit a warning.
+                */
+               if (++i > 2) {
+                       /* Increase the min. delta and try again */
+                       if (!dev->min_delta_ns)
+                               dev->min_delta_ns = 5000;
+                       else
+                               dev->min_delta_ns += dev->min_delta_ns >> 1;
+
+                       printk(KERN_WARNING
+                              "CE: %s increasing min_delta_ns to %lu nsec\n",
+                              dev->name ? dev->name : "?",
+                              dev->min_delta_ns << 1);
+
+                       i = 0;
+               }
+
                now = ktime_get();
-               expires = ktime_add(now, ktime_set(0, dev->min_delta_ns));
+               expires = ktime_add_ns(now, dev->min_delta_ns);
        }
 }
 
 /**
+ * tick_program_event
+ */
+int tick_program_event(ktime_t expires, int force)
+{
+       struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
+
+       return tick_dev_program_event(dev, expires, force);
+}
+
+/**
  * tick_resume_onshot - resume oneshot mode
  */
 void tick_resume_oneshot(void)
@@ -61,7 +93,7 @@ void tick_setup_oneshot(struct clock_event_device *newdev,
 {
        newdev->event_handler = handler;
        clockevents_set_mode(newdev, CLOCK_EVT_MODE_ONESHOT);
-       clockevents_program_event(newdev, next_event, ktime_get());
+       tick_dev_program_event(newdev, next_event, 1);
 }
 
 /**
@@ -96,6 +128,23 @@ int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *))
        return 0;
 }
 
+/**
+ * tick_check_oneshot_mode - check whether the system is in oneshot mode
+ *
+ * returns 1 when either nohz or highres are enabled. otherwise 0.
+ */
+int tick_oneshot_mode_active(void)
+{
+       unsigned long flags;
+       int ret;
+
+       local_irq_save(flags);
+       ret = __get_cpu_var(tick_cpu_device).mode == TICKDEV_MODE_ONESHOT;
+       local_irq_restore(flags);
+
+       return ret;
+}
+
 #ifdef CONFIG_HIGH_RES_TIMERS
 /**
  * tick_init_highres - switch to high resolution mode