[RESEND PATCH v2 2/2] power/idle: enhance the precision of sleep_length

From: Zhaoyang Huang
Date: Fri Jun 17 2016 - 05:14:13 EST


There should be a gap between tick_nohz_idle_enter and
tick_nohz_get_sleep_length when idle, which will cause the
sleep_length is not very precised. Change it in this patch.

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxxxxxx>
---
kernel/time/tick-sched.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 536ada8..ee3be3d 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -975,6 +975,11 @@ void tick_nohz_irq_exit(void)
ktime_t tick_nohz_get_sleep_length(void)
{
struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
+ struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
+ ktime_t now;
+
+ now = ktime_get();
+ ts->sleep_length = ktime_sub(dev->next_event, now);

return ts->sleep_length;
}
--
1.7.9.5