*
* 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>
#include <linux/ktime.h>
#include <linux/module.h>
+/*
+ * Scheduler clock - returns current time in nanosec units.
+ * This is default implementation.
+ * Architectures and sub-architectures can override this.
+ */
+unsigned long long __attribute__((weak)) sched_clock(void)
+{
+ return (unsigned long long)jiffies * (NSEC_PER_SEC / HZ);
+}
+
+static __read_mostly int sched_clock_running;
#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
*/
raw_spinlock_t lock;
- unsigned long prev_jiffies;
- u64 prev_raw;
+ unsigned long tick_jiffies;
u64 tick_raw;
u64 tick_gtod;
u64 clock;
return &per_cpu(sched_clock_data, cpu);
}
-static __read_mostly int sched_clock_running;
-
void sched_clock_init(void)
{
u64 ktime_now = ktime_to_ns(ktime_get());
struct sched_clock_data *scd = cpu_sdc(cpu);
scd->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
- scd->prev_jiffies = now_jiffies;
- scd->prev_raw = 0;
+ scd->tick_jiffies = now_jiffies;
scd->tick_raw = 0;
scd->tick_gtod = ktime_now;
scd->clock = ktime_now;
* - 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 u64 __update_sched_clock(struct sched_clock_data *scd, u64 now)
{
unsigned long now_jiffies = jiffies;
- long delta_jiffies = now_jiffies - scd->prev_jiffies;
+ long delta_jiffies = now_jiffies - scd->tick_jiffies;
u64 clock = scd->clock;
u64 min_clock, max_clock;
- s64 delta = now - scd->prev_raw;
+ s64 delta = now - scd->tick_raw;
WARN_ON_ONCE(!irqs_disabled());
min_clock = scd->tick_gtod + delta_jiffies * TICK_NSEC;
if (unlikely(clock < min_clock))
clock = min_clock;
- scd->prev_raw = now;
- scd->prev_jiffies = now_jiffies;
+ scd->tick_jiffies = now_jiffies;
scd->clock = clock;
+
+ return clock;
}
static void lock_double_clock(struct sched_clock_data *data1,
u64 sched_clock_cpu(int cpu)
{
struct sched_clock_data *scd = cpu_sdc(cpu);
- u64 now, clock;
+ u64 now, clock, this_clock, remote_clock;
if (unlikely(!sched_clock_running))
return 0ull;
now = sched_clock();
if (cpu != raw_smp_processor_id()) {
- /*
- * in order to update a remote cpu's clock based on our
- * unstable raw time rebase it against:
- * tick_raw (offset between raw counters)
- * tick_gotd (tick offset between cpus)
- */
struct sched_clock_data *my_scd = this_scd();
lock_double_clock(scd, my_scd);
- now -= my_scd->tick_raw;
- now += scd->tick_raw;
+ this_clock = __update_sched_clock(my_scd, now);
+ remote_clock = scd->clock;
- now -= my_scd->tick_gtod;
- now += scd->tick_gtod;
+ /*
+ * Use the opportunity that we have both locks
+ * taken to couple the two clocks: we take the
+ * larger time as the latest time for both
+ * runqueues. (this creates monotonic movement)
+ */
+ if (likely(remote_clock < this_clock)) {
+ clock = this_clock;
+ scd->clock = clock;
+ } else {
+ /*
+ * Should be rare, but possible:
+ */
+ clock = remote_clock;
+ my_scd->clock = remote_clock;
+ }
__raw_spin_unlock(&my_scd->lock);
} else {
__raw_spin_lock(&scd->lock);
+ clock = __update_sched_clock(scd, now);
}
- __update_sched_clock(scd, now);
- clock = scd->clock;
-
__raw_spin_unlock(&scd->lock);
return clock;
WARN_ON_ONCE(!irqs_disabled());
- now = sched_clock();
now_gtod = ktime_to_ns(ktime_get());
+ now = sched_clock();
__raw_spin_lock(&scd->lock);
__update_sched_clock(scd, now);
void sched_clock_idle_wakeup_event(u64 delta_ns)
{
struct sched_clock_data *scd = this_scd();
- u64 now = sched_clock();
/*
* Override the previous timestamp and ignore all
* rq clock:
*/
__raw_spin_lock(&scd->lock);
- scd->prev_raw = now;
scd->clock += delta_ns;
__raw_spin_unlock(&scd->lock);
}
EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
+#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */
+
+void sched_clock_init(void)
+{
+ sched_clock_running = 1;
+}
+
+u64 sched_clock_cpu(int cpu)
+{
+ if (unlikely(!sched_clock_running))
+ return 0;
+
+ return sched_clock();
+}
+
#endif
-/*
- * Scheduler clock - returns current time in nanosec units.
- * This is default implementation.
- * Architectures and sub-architectures can override this.
- */
-unsigned long long __attribute__((weak)) sched_clock(void)
+unsigned long long cpu_clock(int cpu)
{
- return (unsigned long long)jiffies * (NSEC_PER_SEC / HZ);
+ unsigned long long clock;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ clock = sched_clock_cpu(cpu);
+ local_irq_restore(flags);
+
+ return clock;
}
+EXPORT_SYMBOL_GPL(cpu_clock);
projects / linux-2.6-omap-h63xx.git / blobdiff