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authorIngo Molnar <mingo@elte.hu>2007-08-23 15:18:02 +0200
committerIngo Molnar <mingo@elte.hu>2007-08-23 15:18:02 +0200
commit2aa44d0567ed21b47b87d68819415d48194cb923 (patch)
tree7be2a8a30a23b363e1e2aecd41934e75f581e115 /kernel
parentb377fd3982ad957c796758a90e2988401a884241 (diff)
downloadlinux-linaro-2aa44d0567ed21b47b87d68819415d48194cb923.tar.gz
sched: sched_clock_idle_[sleep|wakeup]_event()
construct a more or less wall-clock time out of sched_clock(), by using ACPI-idle's existing knowledge about how much time we spent idling. This allows the rq clock to work around TSC-stops-in-C2, TSC-gets-corrupted-in-C3 type of problems. ( Besides the scheduler's statistics this also benefits blktrace and printk-timestamps as well. ) Furthermore, the precise before-C2/C3-sleep and after-C2/C3-wakeup callbacks allow the scheduler to get out the most of the period where the CPU has a reliable TSC. This results in slightly more precise task statistics. the ACPI bits were acked by Len. Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c41
-rw-r--r--kernel/sched_debug.c3
2 files changed, 34 insertions, 10 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 45e17b83b7f..48e7586168e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -262,7 +262,8 @@ struct rq {
s64 clock_max_delta;
unsigned int clock_warps, clock_overflows;
- unsigned int clock_unstable_events;
+ u64 idle_clock;
+ unsigned int clock_deep_idle_events;
u64 tick_timestamp;
atomic_t nr_iowait;
@@ -556,18 +557,40 @@ static inline struct rq *this_rq_lock(void)
}
/*
- * CPU frequency is/was unstable - start new by setting prev_clock_raw:
+ * We are going deep-idle (irqs are disabled):
*/
-void sched_clock_unstable_event(void)
+void sched_clock_idle_sleep_event(void)
{
- unsigned long flags;
- struct rq *rq;
+ struct rq *rq = cpu_rq(smp_processor_id());
- rq = task_rq_lock(current, &flags);
- rq->prev_clock_raw = sched_clock();
- rq->clock_unstable_events++;
- task_rq_unlock(rq, &flags);
+ spin_lock(&rq->lock);
+ __update_rq_clock(rq);
+ spin_unlock(&rq->lock);
+ rq->clock_deep_idle_events++;
+}
+EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event);
+
+/*
+ * We just idled delta nanoseconds (called with irqs disabled):
+ */
+void sched_clock_idle_wakeup_event(u64 delta_ns)
+{
+ struct rq *rq = cpu_rq(smp_processor_id());
+ u64 now = sched_clock();
+
+ rq->idle_clock += delta_ns;
+ /*
+ * Override the previous timestamp and ignore all
+ * sched_clock() deltas that occured while we idled,
+ * and use the PM-provided delta_ns to advance the
+ * rq clock:
+ */
+ spin_lock(&rq->lock);
+ rq->prev_clock_raw = now;
+ rq->clock += delta_ns;
+ spin_unlock(&rq->lock);
}
+EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
/*
* resched_task - mark a task 'to be rescheduled now'.
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index 87e524762b8..ab18f45f2ab 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -154,10 +154,11 @@ static void print_cpu(struct seq_file *m, int cpu)
P(next_balance);
P(curr->pid);
P(clock);
+ P(idle_clock);
P(prev_clock_raw);
P(clock_warps);
P(clock_overflows);
- P(clock_unstable_events);
+ P(clock_deep_idle_events);
P(clock_max_delta);
P(cpu_load[0]);
P(cpu_load[1]);