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-rw-r--r--kernel/sched_clock.c40
1 files changed, 37 insertions, 3 deletions
diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c
index 28ff6bf5e02..8affbfd0cdb 100644
--- a/kernel/sched_clock.c
+++ b/kernel/sched_clock.c
@@ -3,6 +3,9 @@
*
* Copyright (C) 2008 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
*
+ * Updates and enhancements:
+ * Copyright (C) 2008 Red Hat, Inc. Steven Rostedt <srostedt@redhat.com>
+ *
* Based on code by:
* Ingo Molnar <mingo@redhat.com>
* Guillaume Chazarain <guichaz@gmail.com>
@@ -32,6 +35,11 @@
#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
+#define MULTI_SHIFT 15
+/* Max is double, Min is 1/2 */
+#define MAX_MULTI (2LL << MULTI_SHIFT)
+#define MIN_MULTI (1LL << (MULTI_SHIFT-1))
+
struct sched_clock_data {
/*
* Raw spinlock - this is a special case: this might be called
@@ -45,6 +53,7 @@ struct sched_clock_data {
u64 tick_raw;
u64 tick_gtod;
u64 clock;
+ s64 multi;
#ifdef CONFIG_NO_HZ
int check_max;
#endif
@@ -79,6 +88,7 @@ void sched_clock_init(void)
scd->tick_raw = 0;
scd->tick_gtod = ktime_now;
scd->clock = ktime_now;
+ scd->multi = 1 << MULTI_SHIFT;
#ifdef CONFIG_NO_HZ
scd->check_max = 1;
#endif
@@ -134,8 +144,13 @@ static void __update_sched_clock(struct sched_clock_data *scd, u64 now, u64 *tim
WARN_ON_ONCE(!irqs_disabled());
- min_clock = scd->tick_gtod +
- (delta_jiffies ? delta_jiffies - 1 : 0) * TICK_NSEC;
+ /*
+ * At schedule tick the clock can be just under the gtod. We don't
+ * want to push it too prematurely.
+ */
+ min_clock = scd->tick_gtod + (delta_jiffies * TICK_NSEC);
+ if (min_clock > TICK_NSEC)
+ min_clock -= TICK_NSEC / 2;
if (unlikely(delta < 0)) {
clock++;
@@ -149,6 +164,9 @@ static void __update_sched_clock(struct sched_clock_data *scd, u64 now, u64 *tim
*/
max_clock = scd->tick_gtod + (2 + delta_jiffies) * TICK_NSEC;
+ delta *= scd->multi;
+ delta >>= MULTI_SHIFT;
+
if (unlikely(clock + delta > max_clock) && check_max(scd)) {
if (clock < max_clock)
clock = max_clock;
@@ -230,6 +248,7 @@ void sched_clock_tick(void)
{
struct sched_clock_data *scd = this_scd();
unsigned long now_jiffies = jiffies;
+ s64 mult, delta_gtod, delta_raw;
u64 now, now_gtod;
if (unlikely(!sched_clock_running))
@@ -247,9 +266,23 @@ void sched_clock_tick(void)
* already observe 1 new jiffy; adding a new tick_gtod to that would
* increase the clock 2 jiffies.
*/
- scd->tick_jiffies = now_jiffies;
+ delta_gtod = now_gtod - scd->tick_gtod;
+ delta_raw = now - scd->tick_raw;
+
+ if ((long)delta_raw > 0) {
+ mult = delta_gtod << MULTI_SHIFT;
+ do_div(mult, delta_raw);
+ scd->multi = mult;
+ if (scd->multi > MAX_MULTI)
+ scd->multi = MAX_MULTI;
+ else if (scd->multi < MIN_MULTI)
+ scd->multi = MIN_MULTI;
+ } else
+ scd->multi = 1 << MULTI_SHIFT;
+
scd->tick_raw = now;
scd->tick_gtod = now_gtod;
+ scd->tick_jiffies = now_jiffies;
__raw_spin_unlock(&scd->lock);
}
@@ -279,6 +312,7 @@ void sched_clock_idle_wakeup_event(u64 delta_ns)
__raw_spin_lock(&scd->lock);
scd->prev_raw = now;
scd->clock += delta_ns;
+ scd->multi = 1 << MULTI_SHIFT;
__raw_spin_unlock(&scd->lock);
touch_softlockup_watchdog();