source: trunk/packages/xen-3.1/xen-3.1/patches/linux-2.6.18/softlockup-no-idle-hz.patch @ 34

include/linux/sched.h

@@ -211 +211 @@
 extern void scheduler_tick(void);
 
 #ifdef CONFIG_DETECT_SOFTLOCKUP
+extern unsigned long softlockup_get_next_event(void);
 extern void softlockup_tick(void);
 extern void spawn_softlockup_task(void);
 extern void touch_softlockup_watchdog(void);
 #else
+static inline unsigned long softlockup_get_next_event(void)
+{
+        return MAX_JIFFY_OFFSET;
+}
 static inline void softlockup_tick(void)
 {
 }

kernel/softlockup.c

@@ -40 +40 @@
 }
 EXPORT_SYMBOL(touch_softlockup_watchdog);
 
+unsigned long softlockup_get_next_event(void)
+{
+        int this_cpu = smp_processor_id();
+        unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
+
+        if (per_cpu(print_timestamp, this_cpu) == touch_timestamp ||
+                did_panic ||
+                        !per_cpu(watchdog_task, this_cpu))
+                return MAX_JIFFY_OFFSET;
+
+        return max_t(long, 0, touch_timestamp + HZ - jiffies);
+}
+
 /*
  * This callback runs from the timer interrupt, and checks
  * whether the watchdog thread has hung or not:

kernel/timer.c

@@ -485 +485 @@
                 if (hr_expires < 3)
                         return hr_expires + jiffies;
         }
-        hr_expires += jiffies;
+        hr_expires = min_t(unsigned long,
+                           softlockup_get_next_event(),
+                           hr_expires) + jiffies;
 
         base = __get_cpu_var(tvec_bases);
         spin_lock(&base->lock);