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authorPreeti U Murthy <preeti@linux.vnet.ibm.com>2015-01-21 16:27:25 +0530
committerIngo Molnar <mingo@kernel.org>2015-01-30 19:38:52 +0100
commitff6f2d29bd31cdfa1ac494a8b26d2af8ba887d59 (patch)
tree9c40af46ead9789f5c0a6c55ea2f30a18d08d756 /kernel/sched/idle.c
parenta18b5d01819235629289212ad428a5ee2b40f0d9 (diff)
downloadlinux-ff6f2d29bd31cdfa1ac494a8b26d2af8ba887d59.tar.bz2
sched/idle: Add missing checks to the exit condition of cpu_idle_poll()
cpu_idle_poll() is entered into when either the cpu_idle_force_poll is set or tick_check_broadcast_expired() returns true. The exit condition from cpu_idle_poll() is tif_need_resched(). However this does not take into account scenarios where cpu_idle_force_poll changes or tick_check_broadcast_expired() returns false, without setting the resched flag. So a cpu will be caught in cpu_idle_poll() needlessly, thereby wasting power. Add an explicit check on cpu_idle_force_poll and tick_check_broadcast_expired() to the exit condition of cpu_idle_poll() to avoid this. Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: linuxppc-dev@lists.ozlabs.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20150121105655.15279.59626.stgit@preeti.in.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/idle.c')
-rw-r--r--kernel/sched/idle.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index c47fce75e666..aaf1c1d5cf5d 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -47,7 +47,8 @@ static inline int cpu_idle_poll(void)
rcu_idle_enter();
trace_cpu_idle_rcuidle(0, smp_processor_id());
local_irq_enable();
- while (!tif_need_resched())
+ while (!tif_need_resched() &&
+ (cpu_idle_force_poll || tick_check_broadcast_expired()))
cpu_relax();
trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
rcu_idle_exit();