[PATCH] cpuidle: record state entry failed statistics

[Lina Iyer <ilina@codeaurora.org>]

When CPUs fail to enter the chosen idle state it's mostly because of a
pending interrupt. Let's record that and show along with other
statistics for the idle state. This could prove useful in understanding
behavior of the governor and the system during usecases that involve
multiple CPUs.

Signed-off-by: Lina Iyer <ilina@codeaurora.org>
---
 drivers/cpuidle/cpuidle.c | 1 +
 drivers/cpuidle/sysfs.c   | 3 +++
 include/linux/cpuidle.h   | 1 +
 3 files changed, 5 insertions(+)

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 04becd70cc41..8dbf71f6138d 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -302,6 +302,7 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
 		}
 	} else {
 		dev->last_residency_ns = 0;
+		dev->states_usage[index].failed++;
 	}
 
 	return entered_state;
diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c
index 091d1caceb41..f166687b3bcd 100644
--- a/drivers/cpuidle/sysfs.c
+++ b/drivers/cpuidle/sysfs.c
@@ -256,6 +256,7 @@ define_show_state_time_function(exit_latency)
 define_show_state_time_function(target_residency)
 define_show_state_function(power_usage)
 define_show_state_ull_function(usage)
+define_show_state_ull_function(failed)
 define_show_state_str_function(name)
 define_show_state_str_function(desc)
 define_show_state_ull_function(above)
@@ -312,6 +313,7 @@ define_one_state_ro(latency, show_state_exit_latency);
 define_one_state_ro(residency, show_state_target_residency);
 define_one_state_ro(power, show_state_power_usage);
 define_one_state_ro(usage, show_state_usage);
+define_one_state_ro(failed, show_state_failed);
 define_one_state_ro(time, show_state_time);
 define_one_state_rw(disable, show_state_disable, store_state_disable);
 define_one_state_ro(above, show_state_above);
@@ -325,6 +327,7 @@ static struct attribute *cpuidle_state_default_attrs[] = {
 	&attr_residency.attr,
 	&attr_power.attr,
 	&attr_usage.attr,
+	&attr_failed.attr,
 	&attr_time.attr,
 	&attr_disable.attr,
 	&attr_above.attr,
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 75895e6363b8..911b99273eba 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -38,6 +38,7 @@ struct cpuidle_state_usage {
 	u64			time_ns;
 	unsigned long long	above; /* Number of times it's been too deep */
 	unsigned long long	below; /* Number of times it's been too shallow */
+	unsigned long long	failed; /* Number of times it failed to enter */
 #ifdef CONFIG_SUSPEND
 	unsigned long long	s2idle_usage;
 	unsigned long long	s2idle_time; /* in US */
-- 
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