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cpuidle: record state entry failed statistics

PATCH Superseded Lina Iyer 2 participants 3 messages Sep 2, 2020 – Sep 22, 2020

Subsystems (2)
Arm Qualcomm mailing list CPU idle time management framework

v1 of 2 Superseded Latest is v2 →

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Lina Iyer

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#0 lore raw

PATCH 1/1 cpuidle: record state entry failed statistics

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 <[email protected]>
---
 drivers/cpuidle/cpuidle.c | 1 +
 drivers/cpuidle/sysfs.c   | 3 +++
 include/linux/cpuidle.h   | 1 +
 3 files changed, 5 insertions(+)
drivers/cpuidle/cpuidle.c +1 -0
index 04becd70cc41..8dbf71f6138d 100644
@@ -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;
drivers/cpuidle/sysfs.c +3 -0
index 091d1caceb41..f166687b3bcd 100644
@@ -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,
include/linux/cpuidle.h +1 -0
index 75895e6363b8..911b99273eba 100644
@@ -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 */
Signature · 2 lines
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
maintainer
#1 lore raw

Sorry for the delay.

Quoted 7 lines · Lina Iyer

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.

Quoted 5 lines
Signed-off-by Lina Iyer <[email protected]>
---
 drivers/cpuidle/cpuidle.c | 1 +
 drivers/cpuidle/sysfs.c   | 3 +++
 include/linux/cpuidle.h   | 1 +

The documentation needs to be updated too to cover the new state attribute.

Quoted 19 lines
 3 files changed, 5 insertions(+)
drivers/cpuidle/cpuidle.c +1 -0
index 04becd70cc41..8dbf71f6138d 100644
@@ -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;
drivers/cpuidle/sysfs.c +0 -0
index 091d1caceb41..f166687b3bcd 100644

drivers/cpuidle/sysfs.c define_show_state_time_function(exit_latency) · line 259

Quoted 4 lines
drivers/cpuidle/sysfs.c +1 -0
@@ -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)

And what about calling it "rejected" instead of "failed"?

Quoted 35 lines
drivers/cpuidle/sysfs.c +2 -0
 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,
include/linux/cpuidle.h +1 -1
index 75895e6363b8..911b99273eba 100644
@@ -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 */
--

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project

author
#2 lore raw
Quoted 2 lines · Rafael J. Wysocki

Sorry for the delay.

Thanks for the review.

Quoted 8 lines · Lina Iyer
Quoted 7 lines

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.

Quoted 8 lines
Quoted 5 lines
Signed-off-by Lina Iyer <[email protected]>
---
 drivers/cpuidle/cpuidle.c | 1 +
 drivers/cpuidle/sysfs.c   | 3 +++
 include/linux/cpuidle.h   | 1 +

The documentation needs to be updated too to cover the new state attribute.

Sure, will add that in the next spin.

Quoted 13 lines
Quoted 13 lines
 3 files changed, 5 insertions(+)
drivers/cpuidle/cpuidle.c +1 -0
index 04becd70cc41..8dbf71f6138d 100644
@@ -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++;
        }
Quoted 13 lines

drivers/cpuidle/sysfs.c define_show_state_time_function(exit_latency) · line 259

Quoted 10 lines
drivers/cpuidle/cpuidle.c +0 -0
        return entered_state;
drivers/cpuidle/sysfs.c +1 -0
index 091d1caceb41..f166687b3bcd 100644
@@ -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)

And what about calling it "rejected" instead of "failed"?

Works for me.

Thanks,
Lina

Quoted 35 lines
Quoted 35 lines
drivers/cpuidle/sysfs.c +2 -0
 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,
include/linux/cpuidle.h +1 -1
index 75895e6363b8..911b99273eba 100644
@@ -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 */
--

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project