From 0b89e9aa28566cd3e96651dbdd769b026a476d49 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Thu, 6 Mar 2014 11:02:01 +0000 Subject: cpuidle: delay enabling interrupts until all coupled CPUs leave idle As described by a comment at the end of cpuidle_enter_state_coupled it can be inefficient for coupled idle states to return with IRQs enabled since they may proceed to service an interrupt instead of clearing the coupled idle state. Until they have finished & cleared the idle state all CPUs coupled with them will spin rather than being able to enter a safe idle state. Commits e1689795a784 "cpuidle: Add common time keeping and irq enabling" and 554c06ba3ee2 "cpuidle: remove en_core_tk_irqen flag" led to the cpuidle_enter_state enabling interrupts for all idle states, including coupled ones, making this inefficiency unavoidable by drivers & the local_irq_enable near the end of cpuidle_enter_state_coupled redundant. This patch avoids enabling interrupts in cpuidle_enter_state after a coupled state has been entered, allowing them to remain disabled until all coupled CPUs have exited the idle state and cpuidle_enter_state_coupled re-enables them. Cc: Daniel Lezcano Signed-off-by: Paul Burton Signed-off-by: Rafael J. Wysocki --- drivers/cpuidle/cpuidle.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/cpuidle') diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index a55e68f2cfc8..366e6840ec46 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -85,7 +85,8 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, time_end = ktime_get(); - local_irq_enable(); + if (!cpuidle_state_is_coupled(dev, drv, entered_state)) + local_irq_enable(); diff = ktime_to_us(ktime_sub(time_end, time_start)); if (diff > INT_MAX) -- cgit v1.2.3