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authorPaul Burton <paul.burton@imgtec.com>2014-03-06 15:02:01 +0400
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-03-12 03:24:21 +0400
commit0b89e9aa28566cd3e96651dbdd769b026a476d49 (patch)
tree0d16f197e9295367b6a2b5b1aad4a7c66d37ba5a /drivers/cpuidle
parent4b2f0b033a294e6c19d57c5d0a66c000f6299559 (diff)
downloadlinux-0b89e9aa28566cd3e96651dbdd769b026a476d49.tar.xz
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 <daniel.lezcano@linaro.org> Signed-off-by: Paul Burton <paul.burton@imgtec.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpuidle')
-rw-r--r--drivers/cpuidle/cpuidle.c3
1 files changed, 2 insertions, 1 deletions
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)