Thread (18 messages) 18 messages, 4 authors, 2016-02-23

Re: [PATCH V3 2/2] sched: idle: IRQ based next prediction for idle period

From: Daniel Lezcano <hidden>
Date: 2016-02-22 17:29:06
Also in: lkml

On 02/22/2016 04:02 PM, Shreyas B Prabhu wrote:
Hi Daniel,

On 02/16/2016 09:13 PM, Daniel Lezcano wrote:
quoted
+
+/**
+ * sched_idle_next_wakeup - Predict the next wakeup on the current cpu
+ *
+ * The next event on the cpu is based on a statistic approach of the
+ * interrupt events and the timer deterministic value. From the timer
+ * or the irqs, we return the one expected to occur first.
+ *
+ * Returns the expected remaining idle time before being woken up by
+ * an interruption.
+ */
+s64 sched_idle_next_wakeup(void)
+{
+	s64 next_timer = ktime_to_us(tick_nohz_get_sleep_length());
+	s64 next_irq = next_irq_event();
Since next_irq_event() uses RCU and we are in idle this should probably
be wrapped in RCU_NONIDLE().
That is a good point but the function is not supposed to be called in 
the rcu_idle_enter/rcu_idle_exit section which is inside 
cpuidle_idle_call().


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