From: Yunhong Jiang <yunhong.jiang@intel.com>
Date: Tue, 18 Aug 2015 18:23:10 +0000 (-0700)
Subject: Restore the non_hz_full
X-Git-Tag: colorado.1.0~18^2
X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?p=kvmfornfv.git;a=commitdiff_plain;h=fafab8722263f4ab08894e35f4385febbce09dd1

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 76a301b24..016a0bf52 100644
--- 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);
 }