[PATCH] nohz: make the idle_entrytime/idle_exittime correct
From: Yunhong Jiang
Date: Wed Sep 16 2015 - 19:28:32 EST
Currently the idle_entrytime is updated on idle_entry, idle_exit and
get_cpu_idle/iowait_time_us() with non-NULL parameter. This makes the
idle_entrytime not the real entrytime anymore. The idle_exittiime is
updated when exit tickless state, which can be idle tickless or full
tickless.
Change the idle_entrytime to be updated only when enter idle, the
idle_exittime to be updated only when exit idle. Update
the get_cpu_idle_iowait_time_us() accordingly.
Signed-off-by: Yunhong Jiang <yunhong.jiang@xxxxxxxxxxxxxxx>
---
kernel/time/tick-sched.c | 44 ++++++++++++++++----------------------------
1 file changed, 16 insertions(+), 28 deletions(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index c792429e98c6..f8470ff20f77 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -448,7 +448,7 @@ static void tick_nohz_update_jiffies(ktime_t now)
* Updates the per cpu time idle statistics counters
*/
static void
-update_ts_time_stats(int cpu, struct tick_sched *ts, ktime_t now, u64 *last_update_time)
+update_ts_time_stats(int cpu, struct tick_sched *ts, ktime_t now)
{
ktime_t delta;
@@ -458,17 +458,13 @@ update_ts_time_stats(int cpu, struct tick_sched *ts, ktime_t now, u64 *last_upda
ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta);
else
ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
- ts->idle_entrytime = now;
}
-
- if (last_update_time)
- *last_update_time = ktime_to_us(now);
-
}
static void tick_nohz_stop_idle(struct tick_sched *ts, ktime_t now)
{
- update_ts_time_stats(smp_processor_id(), ts, now, NULL);
+ update_ts_time_stats(smp_processor_id(), ts, now);
+ ts->idle_exittime = now;
ts->idle_active = 0;
sched_clock_idle_wakeup_event(0);
@@ -507,21 +503,16 @@ u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time)
return -1;
now = ktime_get();
- if (last_update_time) {
- update_ts_time_stats(cpu, ts, now, last_update_time);
- idle = ts->idle_sleeptime;
- } else {
- if (ts->idle_active && !nr_iowait_cpu(cpu)) {
- ktime_t delta = ktime_sub(now, ts->idle_entrytime);
+ idle = ts->idle_sleeptime;
+ if (ts->idle_active && !nr_iowait_cpu(cpu)) {
+ ktime_t delta = ktime_sub(now, ts->idle_entrytime);
- idle = ktime_add(ts->idle_sleeptime, delta);
- } else {
- idle = ts->idle_sleeptime;
- }
+ idle = ktime_add(ts->idle_sleeptime, delta);
}
+ if (last_update_time)
+ *last_update_time = ktime_to_us(now);
return ktime_to_us(idle);
-
}
EXPORT_SYMBOL_GPL(get_cpu_idle_time_us);
@@ -548,19 +539,16 @@ u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time)
return -1;
now = ktime_get();
- if (last_update_time) {
- update_ts_time_stats(cpu, ts, now, last_update_time);
- iowait = ts->iowait_sleeptime;
- } else {
- if (ts->idle_active && nr_iowait_cpu(cpu) > 0) {
- ktime_t delta = ktime_sub(now, ts->idle_entrytime);
+ iowait = ts->iowait_sleeptime;
+ if (ts->idle_active && nr_iowait_cpu(cpu) > 0) {
+ ktime_t delta = ktime_sub(now, ts->idle_entrytime);
- iowait = ktime_add(ts->iowait_sleeptime, delta);
- } else {
- iowait = ts->iowait_sleeptime;
- }
+ iowait = ktime_add(ts->iowait_sleeptime, delta);
}
+ if (last_update_time)
+ *last_update_time = ktime_to_us(now);
+
return ktime_to_us(iowait);
}
EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us);
--
1.8.3.1
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