- Check whether we've recorded this tick in ts_ticks on another cpu in

   sched_tick() to prevent multiple increments for one tick.  This pushes
   the value out of range and breaks priority calculation.

Reviewed by:	kib
Found by:	pho/nokia
Sponsored by:	Nokia
MFC after:	3 days

1 files changed, 6 insertions, 0 deletions

diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c
index 172f41a..c3916c9 100644
--- a/sys/kern/sched_ule.c
+++ b/sys/kern/sched_ule.c
@@ -2163,6 +2163,12 @@ sched_tick(void)
 	struct td_sched *ts;
 
 	ts = curthread->td_sched;
+	/*
+	 * Ticks is updated asynchronously on a single cpu.  Check here to
+	 * avoid incrementing ts_ticks multiple times in a single tick.
+	 */
+	if (ts->ts_ltick == ticks)
+		return;
 	/* Adjust ticks for pctcpu */
 	ts->ts_ticks += 1 << SCHED_TICK_SHIFT;
 	ts->ts_ltick = ticks;