Commit ce0cb029 authored Dec 16, 2014 by Joonwoo Park Committed by Matt Wagantall May 30, 2015

sched: take account of irq preemption when calculating irqload delta



If irq raises while sched_irqload() is calculating irqload delta,
sched_account_irqtime() can update rq's irqload_ts which can be greater
than the jiffies stored in sched_irqload()'s context so delta can be
negative.  This negative delta means there was recent irq occurence.
So remove improper BUG_ON().

CRs-fixed: 771894
Change-Id: I5bb01b50ec84c14bf9f26dd9c95de82ec2cd19b5
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>

parent 6c352f2c

kernel/sched/sched.h

+6 −1

Original line number	Diff line number	Diff line
		@@ -948,7 +948,12 @@ static inline u64 sched_irqload(int cpu)
		s64 delta;

		delta = get_jiffies_64() - rq->irqload_ts;
		BUG_ON(delta < 0);
		/*
		* Current context can be preempted by irq and rq->irqload_ts can be
		* updated by irq context so that delta can be negative.
		* But this is okay and we can safely return as this means there
		* was recent irq occurrence.
		*/

		if (delta < SCHED_HIGH_IRQ_TIMEOUT)
		return rq->avg_irqload;