[PATCH v2 2/3] cpuidle: allow setting deepest idle

Jacob Pan
2016-11-14T18:50:36Z

When idle injection is used to cap power, we need to override
governor's choice of idle states. This patch allows caller to select
the deepest idle state on a CPU therefore achieve the maximum
potential power saving.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
drivers/cpuidle/cpuidle.c | 11 +++++++++++
include/linux/cpuidle.h | 4 +++-
kernel/sched/idle.c | 3 +++
3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index c73207a..887a52a 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -97,6 +97,17 @@ static int find_deepest_state(struct cpuidle_driver *drv,
return ret;
}

+/* Set the current cpu to use the deepest idle state, override governors */
+void cpuidle_use_deepest_state(bool enable)
+{
+ struct cpuidle_device *dev;
+
+ preempt_disable();
+ dev = cpuidle_get_device();
+ dev->use_deepest_state = enable;
+ preempt_enable();
+}
+
#ifdef CONFIG_SUSPEND
/**
* cpuidle_find_deepest_state - Find the deepest available idle state.
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index bb31373..7f93c63 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -74,6 +74,7 @@ struct cpuidle_state {
struct cpuidle_device {
unsigned int registered:1;
unsigned int enabled:1;
+ unsigned int use_deepest_state:1;
unsigned int cpu;

int last_residency;
@@ -192,11 +193,12 @@ static inline struct cpuidle_driver *cpuidle_get_cpu_driver(
static inline struct cpuidle_device *cpuidle_get_device(void) {return NULL; }
#endif

-#if defined(CONFIG_CPU_IDLE) && defined(CONFIG_SUSPEND)
+#if defined(CONFIG_CPU_IDLE)
extern int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
struct cpuidle_device *dev);
extern int cpuidle_enter_freeze(struct cpuidle_driver *drv,
struct cpuidle_device *dev);
+extern void cpuidle_use_deepest_state(bool enable);
#else
static inline int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
struct cpuidle_device *dev)
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index cb6442f..9e80f32 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -173,6 +173,9 @@ static void cpuidle_idle_call(void)

next_state = cpuidle_find_deepest_state(drv, dev);
call_cpuidle(drv, dev, next_state);
+ } else if (dev->use_deepest_state) {
+ next_state = cpuidle_find_deepest_state(drv, dev);
+ call_cpuidle(drv, dev, next_state);
} else {
/*
* Ask the cpuidle framework to choose a convenient idle state.
--
1.9.1