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author | Ingo Molnar <mingo@elte.hu> | 2007-08-23 15:18:02 +0200 |
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committer | Ingo Molnar <mingo@elte.hu> | 2007-08-23 15:18:02 +0200 |
commit | 2aa44d0567ed21b47b87d68819415d48194cb923 (patch) | |
tree | 7be2a8a30a23b363e1e2aecd41934e75f581e115 /kernel | |
parent | b377fd3982ad957c796758a90e2988401a884241 (diff) | |
download | linux-2aa44d0567ed21b47b87d68819415d48194cb923.tar.gz linux-2aa44d0567ed21b47b87d68819415d48194cb923.tar.bz2 linux-2aa44d0567ed21b47b87d68819415d48194cb923.zip |
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.c | 41 | ||||
-rw-r--r-- | kernel/sched_debug.c | 3 |
2 files changed, 34 insertions, 10 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 45e17b83b7f1..48e7586168ef 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 87e524762b85..ab18f45f2ab2 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]); |