sched_clock: only update deltas with local reads.

[deliverable/linux.git] / kernel / sched_clock.c

diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c
index 55fca1e9e12ac1fce4c4a7fd04f35866fde6a229..ee7cce5029ce9cf8c5c53255d21f3f5c3e916b85 100644 (file)
--- a/kernel/sched_clock.c
+++ b/kernel/sched_clock.c
@@ -124,7 +124,7 @@ static int check_max(struct sched_clock_data *scd)
  *  - filter out backward motion
  *  - use jiffies to generate a min,max window to clip the raw values
  */
-static void __update_sched_clock(struct sched_clock_data *scd, u64 now)
+static void __update_sched_clock(struct sched_clock_data *scd, u64 now, u64 *time)
 {
        unsigned long now_jiffies = jiffies;
        long delta_jiffies = now_jiffies - scd->tick_jiffies;
@@ -162,8 +162,12 @@ static void __update_sched_clock(struct sched_clock_data *scd, u64 now)
        if (unlikely(clock < min_clock))
                clock = min_clock;
 
-       scd->prev_raw = now;
-       scd->clock = clock;
+       if (time)
+               *time = clock;
+       else {
+               scd->prev_raw = now;
+               scd->clock = clock;
+       }
 }
 
 static void lock_double_clock(struct sched_clock_data *data1,
@@ -207,15 +211,18 @@ u64 sched_clock_cpu(int cpu)
                now -= scd->tick_gtod;
 
                __raw_spin_unlock(&my_scd->lock);
+
+               __update_sched_clock(scd, now, &clock);
+
+               __raw_spin_unlock(&scd->lock);
+
        } else {
                __raw_spin_lock(&scd->lock);
+               __update_sched_clock(scd, now, NULL);
+               clock = scd->clock;
+               __raw_spin_unlock(&scd->lock);
        }
 
-       __update_sched_clock(scd, now);
-       clock = scd->clock;
-
-       __raw_spin_unlock(&scd->lock);
-
        return clock;
 }
 
@@ -234,7 +241,7 @@ void sched_clock_tick(void)
        now_gtod = ktime_to_ns(ktime_get());
 
        __raw_spin_lock(&scd->lock);
-       __update_sched_clock(scd, now);
+       __update_sched_clock(scd, now, NULL);
        /*
         * update tick_gtod after __update_sched_clock() because that will
         * already observe 1 new jiffy; adding a new tick_gtod to that would