linux-kernel - [RFC PATCH v2 5/8] timers: keep sleep length updated as needed

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Message-Id: <1506756034-6340-6-git-send-email-aubrey.li@intel.com>
Date:   Sat, 30 Sep 2017 15:20:31 +0800
From:   Aubrey Li <aubrey.li@...el.com>
To:     tglx@...utronix.de, peterz@...radead.org, rjw@...ysocki.net,
        len.brown@...el.com, ak@...ux.intel.com, tim.c.chen@...ux.intel.com
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Aubrey Li <aubrey.li@...el.com>
Subject: [RFC PATCH v2 5/8] timers: keep sleep length updated as needed

sleep length indicates how long we'll be idle. Currently, it's updated
only when tick nohz enters. These patch series make a new requirement
with tick, so we should keep sleep length updated as needed
---
 kernel/time/tick-sched.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index d663fab..94fb9b8 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -1008,8 +1008,11 @@ void tick_nohz_irq_exit(void)
  */
 ktime_t tick_nohz_get_sleep_length(void)
 {
+	struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
 	struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
 
+	ts->sleep_length = ktime_sub(dev->next_event, ktime_get());
+
 	return ts->sleep_length;
 }
 
-- 
2.7.4