Restore the non_hz_full

Please refer to http://comments.gmane.org/gmane.linux.kernel/1891417, the
last two mails on this discussion.

The non_hz_full is important for RT, so take it back temporarily.

Unluckily I didn't find the corresponding reverting patch on the RT tree.

Upstream status: pending

Change-Id: I2748a8f9b7a98ef2185a1da60089984432393eff

Signed-off-by: Yunhong Jiang <yunhong.jiang@linux.intel.com>

diff --git a/kernel/kernel/time/timer.c b/kernel/kernel/time/timer.c
index 76a301b..016a0bf 100644 (file)
--- a/kernel/kernel/time/timer.c
+++ b/kernel/kernel/time/timer.c
@@ -1453,9 +1453,11 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
         * the base lock to check when the next timer is pending and so
         * we assume the next jiffy.
         */
-       return basem + TICK_NSEC;
-#endif
+       if (!spin_do_trylock(&base->lock))
+               return basem + TICK_NSEC;
+#else
        spin_lock(&base->lock);
+#endif
        if (base->active_timers) {
                if (time_before_eq(base->next_timer, base->timer_jiffies))
                        base->next_timer = __next_timer_interrupt(base);
@@ -1465,7 +1467,11 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
                else
                        expires = basem + (nextevt - basej) * TICK_NSEC;
        }
+#ifdef CONFIG_PREEMPT_RT_FULL
+       rt_spin_unlock(&base->lock);
+#else
        spin_unlock(&base->lock);
+#endif
 
        return cmp_next_hrtimer_event(basem, expires);
 }