From 2aa44d0567ed21b47b87d68819415d48194cb923 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 23 Aug 2007 15:18:02 +0200 Subject: 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 Acked-by: Len Brown --- kernel/sched.c | 41 ++++++++++++++++++++++++++++++++--------- 1 file changed, 32 insertions(+), 9 deletions(-) (limited to 'kernel/sched.c') 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'. -- cgit v1.2.3