Messages in this thread Patch in this message | | | Subject | [PATCH V2] cpuidle: Add missing checks to the exit condition of cpu_idle_poll() | From | Preeti U Murthy <> | Date | Wed, 21 Jan 2015 16:27:25 +0530 |
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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> --- Changes from V1: Modified the Changelog
kernel/sched/idle.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index c47fce7..aaf1c1d 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();
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