[v6,1/4] PM: Add sysfs files to represent time spent in hardware sleep state
Commit Message
Userspace can't easily discover how much of a sleep cycle was spent in a
hardware sleep state without using kernel tracing and vendor specific sysfs
or debugfs files.
To make this information more discoverable, introduce two new sysfs files:
1) The time spent in a hw sleep state for last cycle.
2) The time spent in a hw sleep state since the kernel booted
Both of these files will be present only if the system supports s2idle.
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
v5->v6:
* Add total attribute as well
* Change text for documentation
* Adjust flow of is_visible callback.
* If overflow was detected in total attribute return -EOVERFLOW
* Rename symbol
* Add stub for symbol for builds without CONFIG_PM_SLEEP
v4->v5:
* Provide time in microseconds instead of percent. Userspace can convert
this if desirable.
---
Documentation/ABI/testing/sysfs-power | 27 ++++++++++++++++
include/linux/suspend.h | 5 +++
kernel/power/main.c | 45 +++++++++++++++++++++++++++
3 files changed, 77 insertions(+)
Comments
Hi Mario,
On Mon, 2023-04-03 at 16:18 -0500, Mario Limonciello wrote:
> Userspace can't easily discover how much of a sleep cycle was spent in a
> hardware sleep state without using kernel tracing and vendor specific sysfs
> or debugfs files.
>
> To make this information more discoverable, introduce two new sysfs files:
> 1) The time spent in a hw sleep state for last cycle.
> 2) The time spent in a hw sleep state since the kernel booted
> Both of these files will be present only if the system supports s2idle.
>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> v5->v6:
> * Add total attribute as well
> * Change text for documentation
> * Adjust flow of is_visible callback.
> * If overflow was detected in total attribute return -EOVERFLOW
> * Rename symbol
> * Add stub for symbol for builds without CONFIG_PM_SLEEP
> v4->v5:
> * Provide time in microseconds instead of percent. Userspace can convert
> this if desirable.
> ---
> Documentation/ABI/testing/sysfs-power | 27 ++++++++++++++++
> include/linux/suspend.h | 5 +++
> kernel/power/main.c | 45 +++++++++++++++++++++++++++
> 3 files changed, 77 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-power
> b/Documentation/ABI/testing/sysfs-power
> index f99d433ff311..37240575d282 100644
> --- a/Documentation/ABI/testing/sysfs-power
> +++ b/Documentation/ABI/testing/sysfs-power
> @@ -413,6 +413,33 @@ Description:
> The /sys/power/suspend_stats/last_failed_step file contains
> the last failed step in the suspend/resume path.
>
> +What: /sys/power/suspend_stats/last_hw_sleep
> +Date: June 2023
> +Contact: Mario Limonciello <mario.limonciello@amd.com>
> +Description:
> + The /sys/power/suspend_stats/last_hw_sleep file
> + contains the duration of time spent in a hardware sleep
> + state in the most recent system suspend-resume cycle.
> + This number is measured in microseconds.
> +
> + NOTE: Limitations in the size of the hardware counters may
> + cause this value to be inaccurate in longer sleep cycles.
> +
> +What: /sys/power/suspend_stats/total_hw_sleep
> +Date: June 2023
> +Contact: Mario Limonciello <mario.limonciello@amd.com>
> +Description:
> + The /sys/power/suspend_stats/total_hw_sleep file
> + contains the aggregate of time spent in a hardware sleep
> + state since the kernel was booted. This number
> + is measured in microseconds.
> +
> + NOTE: Limitations in the size of the hardware counters may
> + cause this value to be inaccurate in longer sleep cycles.
> +
> + If an overflow has been detected this file will return
> + -EOVERFLOW.
> +
> What: /sys/power/sync_on_suspend
> Date: October 2019
> Contact: Jonas Meurer <jonas@freesources.org>
> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
> index cfe19a028918..069ef0c0ae57 100644
> --- a/include/linux/suspend.h
> +++ b/include/linux/suspend.h
> @@ -68,6 +68,8 @@ struct suspend_stats {
> int last_failed_errno;
> int errno[REC_FAILED_NUM];
> int last_failed_step;
> + u64 last_hw_sleep;
> + u64 total_hw_sleep;
> enum suspend_stat_step failed_steps[REC_FAILED_NUM];
> };
>
> @@ -489,6 +491,7 @@ void restore_processor_state(void);
> extern int register_pm_notifier(struct notifier_block *nb);
> extern int unregister_pm_notifier(struct notifier_block *nb);
> extern void ksys_sync_helper(void);
> +extern void pm_report_hw_sleep_time(u64 t);
>
> #define pm_notifier(fn, pri) { \
> static struct notifier_block fn##_nb = \
> @@ -526,6 +529,8 @@ static inline int unregister_pm_notifier(struct
> notifier_block *nb)
> return 0;
> }
>
> +static inline void pm_report_hw_sleep_time(u64 t) {};
> +
> static inline void ksys_sync_helper(void) {}
>
> #define pm_notifier(fn, pri) do { (void)(fn); } while (0)
> diff --git a/kernel/power/main.c b/kernel/power/main.c
> index 31ec4a9b9d70..ffd4dd43cbdd 100644
> --- a/kernel/power/main.c
> +++ b/kernel/power/main.c
> @@ -6,6 +6,7 @@
> * Copyright (c) 2003 Open Source Development Lab
> */
>
> +#include <linux/acpi.h>
> #include <linux/export.h>
> #include <linux/kobject.h>
> #include <linux/string.h>
> @@ -83,6 +84,18 @@ int unregister_pm_notifier(struct notifier_block *nb)
> }
> EXPORT_SYMBOL_GPL(unregister_pm_notifier);
>
> +void pm_report_hw_sleep_time(u64 t)
> +{
> + suspend_stats.last_hw_sleep = t;
> + if (suspend_stats.total_hw_sleep == -EOVERFLOW)
> + return;
> + if (suspend_stats.total_hw_sleep + t < suspend_stats.total_hw_sleep)
> + suspend_stats.total_hw_sleep = -EOVERFLOW;
> + else
> + suspend_stats.total_hw_sleep += t;
total_hw_sleep is u64. At microsecond granularity it will never realistically
overflow and isn't worth the check IMO. The overflow concern comes from the u32
hardware counter, but I don't think there's a good way to detect it.
You could just report the maximum hardware counter time as max_hw_sleep so users
know the value isn't reliable if suspended for longer than that.
David
> +}
> +EXPORT_SYMBOL_GPL(pm_report_hw_sleep_time);
> +
> int pm_notifier_call_chain_robust(unsigned long val_up, unsigned long
> val_down)
> {
> int ret;
> @@ -377,6 +390,22 @@ static ssize_t last_failed_step_show(struct kobject
> *kobj,
> }
> static struct kobj_attribute last_failed_step = __ATTR_RO(last_failed_step);
>
> +static ssize_t last_hw_sleep_show(struct kobject *kobj,
> + struct kobj_attribute *attr, char *buf)
> +{
> + return sysfs_emit(buf, "%llu\n", suspend_stats.last_hw_sleep);
> +}
> +static struct kobj_attribute last_hw_sleep = __ATTR_RO(last_hw_sleep);
> +
> +static ssize_t total_hw_sleep_show(struct kobject *kobj,
> + struct kobj_attribute *attr, char *buf)
> +{
> + if (suspend_stats.total_hw_sleep == -EOVERFLOW)
> + return suspend_stats.total_hw_sleep;
> + return sysfs_emit(buf, "%llu\n", suspend_stats.total_hw_sleep);
> +}
> +static struct kobj_attribute total_hw_sleep = __ATTR_RO(total_hw_sleep);
> +
> static struct attribute *suspend_attrs[] = {
> &success.attr,
> &fail.attr,
> @@ -391,12 +420,28 @@ static struct attribute *suspend_attrs[] = {
> &last_failed_dev.attr,
> &last_failed_errno.attr,
> &last_failed_step.attr,
> + &last_hw_sleep.attr,
> + &total_hw_sleep.attr,
> NULL,
> };
>
> +static umode_t suspend_attr_is_visible(struct kobject *kobj, struct attribute
> *attr, int idx)
> +{
> + if (attr != &last_hw_sleep.attr &&
> + attr != &total_hw_sleep.attr)
> + return 0444;
> +
> +#ifdef CONFIG_ACPI
> + if (acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0)
> + return 0444;
> +#endif
> + return 0;
> +}
> +
> static const struct attribute_group suspend_attr_group = {
> .name = "suspend_stats",
> .attrs = suspend_attrs,
> + .is_visible = suspend_attr_is_visible,
> };
>
> #ifdef CONFIG_DEBUG_FS
Hi,
On 4/5/23 02:42, Box, David E wrote:
> Hi Mario,
>
> On Mon, 2023-04-03 at 16:18 -0500, Mario Limonciello wrote:
>> Userspace can't easily discover how much of a sleep cycle was spent in a
>> hardware sleep state without using kernel tracing and vendor specific sysfs
>> or debugfs files.
>>
>> To make this information more discoverable, introduce two new sysfs files:
>> 1) The time spent in a hw sleep state for last cycle.
>> 2) The time spent in a hw sleep state since the kernel booted
>> Both of these files will be present only if the system supports s2idle.
>>
>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>> ---
>> v5->v6:
>> * Add total attribute as well
>> * Change text for documentation
>> * Adjust flow of is_visible callback.
>> * If overflow was detected in total attribute return -EOVERFLOW
>> * Rename symbol
>> * Add stub for symbol for builds without CONFIG_PM_SLEEP
>> v4->v5:
>> * Provide time in microseconds instead of percent. Userspace can convert
>> this if desirable.
>> ---
>> Documentation/ABI/testing/sysfs-power | 27 ++++++++++++++++
>> include/linux/suspend.h | 5 +++
>> kernel/power/main.c | 45 +++++++++++++++++++++++++++
>> 3 files changed, 77 insertions(+)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-power
>> b/Documentation/ABI/testing/sysfs-power
>> index f99d433ff311..37240575d282 100644
>> --- a/Documentation/ABI/testing/sysfs-power
>> +++ b/Documentation/ABI/testing/sysfs-power
>> @@ -413,6 +413,33 @@ Description:
>> The /sys/power/suspend_stats/last_failed_step file contains
>> the last failed step in the suspend/resume path.
>>
>> +What: /sys/power/suspend_stats/last_hw_sleep
>> +Date: June 2023
>> +Contact: Mario Limonciello <mario.limonciello@amd.com>
>> +Description:
>> + The /sys/power/suspend_stats/last_hw_sleep file
>> + contains the duration of time spent in a hardware sleep
>> + state in the most recent system suspend-resume cycle.
>> + This number is measured in microseconds.
>> +
>> + NOTE: Limitations in the size of the hardware counters may
>> + cause this value to be inaccurate in longer sleep cycles.
>> +
>> +What: /sys/power/suspend_stats/total_hw_sleep
>> +Date: June 2023
>> +Contact: Mario Limonciello <mario.limonciello@amd.com>
>> +Description:
>> + The /sys/power/suspend_stats/total_hw_sleep file
>> + contains the aggregate of time spent in a hardware sleep
>> + state since the kernel was booted. This number
>> + is measured in microseconds.
>> +
>> + NOTE: Limitations in the size of the hardware counters may
>> + cause this value to be inaccurate in longer sleep cycles.
>> +
>> + If an overflow has been detected this file will return
>> + -EOVERFLOW.
>> +
>> What: /sys/power/sync_on_suspend
>> Date: October 2019
>> Contact: Jonas Meurer <jonas@freesources.org>
>> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
>> index cfe19a028918..069ef0c0ae57 100644
>> --- a/include/linux/suspend.h
>> +++ b/include/linux/suspend.h
>> @@ -68,6 +68,8 @@ struct suspend_stats {
>> int last_failed_errno;
>> int errno[REC_FAILED_NUM];
>> int last_failed_step;
>> + u64 last_hw_sleep;
>> + u64 total_hw_sleep;
>> enum suspend_stat_step failed_steps[REC_FAILED_NUM];
>> };
>>
>> @@ -489,6 +491,7 @@ void restore_processor_state(void);
>> extern int register_pm_notifier(struct notifier_block *nb);
>> extern int unregister_pm_notifier(struct notifier_block *nb);
>> extern void ksys_sync_helper(void);
>> +extern void pm_report_hw_sleep_time(u64 t);
>>
>> #define pm_notifier(fn, pri) { \
>> static struct notifier_block fn##_nb = \
>> @@ -526,6 +529,8 @@ static inline int unregister_pm_notifier(struct
>> notifier_block *nb)
>> return 0;
>> }
>>
>> +static inline void pm_report_hw_sleep_time(u64 t) {};
>> +
>> static inline void ksys_sync_helper(void) {}
>>
>> #define pm_notifier(fn, pri) do { (void)(fn); } while (0)
>> diff --git a/kernel/power/main.c b/kernel/power/main.c
>> index 31ec4a9b9d70..ffd4dd43cbdd 100644
>> --- a/kernel/power/main.c
>> +++ b/kernel/power/main.c
>> @@ -6,6 +6,7 @@
>> * Copyright (c) 2003 Open Source Development Lab
>> */
>>
>> +#include <linux/acpi.h>
>> #include <linux/export.h>
>> #include <linux/kobject.h>
>> #include <linux/string.h>
>> @@ -83,6 +84,18 @@ int unregister_pm_notifier(struct notifier_block *nb)
>> }
>> EXPORT_SYMBOL_GPL(unregister_pm_notifier);
>>
>> +void pm_report_hw_sleep_time(u64 t)
>> +{
>> + suspend_stats.last_hw_sleep = t;
>> + if (suspend_stats.total_hw_sleep == -EOVERFLOW)
>> + return;
>> + if (suspend_stats.total_hw_sleep + t < suspend_stats.total_hw_sleep)
>> + suspend_stats.total_hw_sleep = -EOVERFLOW;
>> + else
>> + suspend_stats.total_hw_sleep += t;
>
> total_hw_sleep is u64. At microsecond granularity it will never realistically
> overflow and isn't worth the check IMO. The overflow concern comes from the u32
> hardware counter, but I don't think there's a good way to detect it.
>
> You could just report the maximum hardware counter time as max_hw_sleep so users
> know the value isn't reliable if suspended for longer than that.
Yes I think we need to let userspace know the longest hw-sleep time
the hw can reliably record and then userspace can (and should) chose
to not use/check the counters when the total suspend time is bigger
then the max hw-sleep time.
Other then that this patch-set seems like a good idea to me
and I have no objections / remarks on the pdx86 bits.
Regards,
Hans
>> +}
>> +EXPORT_SYMBOL_GPL(pm_report_hw_sleep_time);
>> +
>> int pm_notifier_call_chain_robust(unsigned long val_up, unsigned long
>> val_down)
>> {
>> int ret;
>> @@ -377,6 +390,22 @@ static ssize_t last_failed_step_show(struct kobject
>> *kobj,
>> }
>> static struct kobj_attribute last_failed_step = __ATTR_RO(last_failed_step);
>>
>> +static ssize_t last_hw_sleep_show(struct kobject *kobj,
>> + struct kobj_attribute *attr, char *buf)
>> +{
>> + return sysfs_emit(buf, "%llu\n", suspend_stats.last_hw_sleep);
>> +}
>> +static struct kobj_attribute last_hw_sleep = __ATTR_RO(last_hw_sleep);
>> +
>> +static ssize_t total_hw_sleep_show(struct kobject *kobj,
>> + struct kobj_attribute *attr, char *buf)
>> +{
>> + if (suspend_stats.total_hw_sleep == -EOVERFLOW)
>> + return suspend_stats.total_hw_sleep;
>> + return sysfs_emit(buf, "%llu\n", suspend_stats.total_hw_sleep);
>> +}
>> +static struct kobj_attribute total_hw_sleep = __ATTR_RO(total_hw_sleep);
>> +
>> static struct attribute *suspend_attrs[] = {
>> &success.attr,
>> &fail.attr,
>> @@ -391,12 +420,28 @@ static struct attribute *suspend_attrs[] = {
>> &last_failed_dev.attr,
>> &last_failed_errno.attr,
>> &last_failed_step.attr,
>> + &last_hw_sleep.attr,
>> + &total_hw_sleep.attr,
>> NULL,
>> };
>>
>> +static umode_t suspend_attr_is_visible(struct kobject *kobj, struct attribute
>> *attr, int idx)
>> +{
>> + if (attr != &last_hw_sleep.attr &&
>> + attr != &total_hw_sleep.attr)
>> + return 0444;
>> +
>> +#ifdef CONFIG_ACPI
>> + if (acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0)
>> + return 0444;
>> +#endif
>> + return 0;
>> +}
>> +
>> static const struct attribute_group suspend_attr_group = {
>> .name = "suspend_stats",
>> .attrs = suspend_attrs,
>> + .is_visible = suspend_attr_is_visible,
>> };
>>
>> #ifdef CONFIG_DEBUG_FS
@@ -413,6 +413,33 @@ Description:
The /sys/power/suspend_stats/last_failed_step file contains
the last failed step in the suspend/resume path.
+What: /sys/power/suspend_stats/last_hw_sleep
+Date: June 2023
+Contact: Mario Limonciello <mario.limonciello@amd.com>
+Description:
+ The /sys/power/suspend_stats/last_hw_sleep file
+ contains the duration of time spent in a hardware sleep
+ state in the most recent system suspend-resume cycle.
+ This number is measured in microseconds.
+
+ NOTE: Limitations in the size of the hardware counters may
+ cause this value to be inaccurate in longer sleep cycles.
+
+What: /sys/power/suspend_stats/total_hw_sleep
+Date: June 2023
+Contact: Mario Limonciello <mario.limonciello@amd.com>
+Description:
+ The /sys/power/suspend_stats/total_hw_sleep file
+ contains the aggregate of time spent in a hardware sleep
+ state since the kernel was booted. This number
+ is measured in microseconds.
+
+ NOTE: Limitations in the size of the hardware counters may
+ cause this value to be inaccurate in longer sleep cycles.
+
+ If an overflow has been detected this file will return
+ -EOVERFLOW.
+
What: /sys/power/sync_on_suspend
Date: October 2019
Contact: Jonas Meurer <jonas@freesources.org>
@@ -68,6 +68,8 @@ struct suspend_stats {
int last_failed_errno;
int errno[REC_FAILED_NUM];
int last_failed_step;
+ u64 last_hw_sleep;
+ u64 total_hw_sleep;
enum suspend_stat_step failed_steps[REC_FAILED_NUM];
};
@@ -489,6 +491,7 @@ void restore_processor_state(void);
extern int register_pm_notifier(struct notifier_block *nb);
extern int unregister_pm_notifier(struct notifier_block *nb);
extern void ksys_sync_helper(void);
+extern void pm_report_hw_sleep_time(u64 t);
#define pm_notifier(fn, pri) { \
static struct notifier_block fn##_nb = \
@@ -526,6 +529,8 @@ static inline int unregister_pm_notifier(struct notifier_block *nb)
return 0;
}
+static inline void pm_report_hw_sleep_time(u64 t) {};
+
static inline void ksys_sync_helper(void) {}
#define pm_notifier(fn, pri) do { (void)(fn); } while (0)
@@ -6,6 +6,7 @@
* Copyright (c) 2003 Open Source Development Lab
*/
+#include <linux/acpi.h>
#include <linux/export.h>
#include <linux/kobject.h>
#include <linux/string.h>
@@ -83,6 +84,18 @@ int unregister_pm_notifier(struct notifier_block *nb)
}
EXPORT_SYMBOL_GPL(unregister_pm_notifier);
+void pm_report_hw_sleep_time(u64 t)
+{
+ suspend_stats.last_hw_sleep = t;
+ if (suspend_stats.total_hw_sleep == -EOVERFLOW)
+ return;
+ if (suspend_stats.total_hw_sleep + t < suspend_stats.total_hw_sleep)
+ suspend_stats.total_hw_sleep = -EOVERFLOW;
+ else
+ suspend_stats.total_hw_sleep += t;
+}
+EXPORT_SYMBOL_GPL(pm_report_hw_sleep_time);
+
int pm_notifier_call_chain_robust(unsigned long val_up, unsigned long val_down)
{
int ret;
@@ -377,6 +390,22 @@ static ssize_t last_failed_step_show(struct kobject *kobj,
}
static struct kobj_attribute last_failed_step = __ATTR_RO(last_failed_step);
+static ssize_t last_hw_sleep_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%llu\n", suspend_stats.last_hw_sleep);
+}
+static struct kobj_attribute last_hw_sleep = __ATTR_RO(last_hw_sleep);
+
+static ssize_t total_hw_sleep_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ if (suspend_stats.total_hw_sleep == -EOVERFLOW)
+ return suspend_stats.total_hw_sleep;
+ return sysfs_emit(buf, "%llu\n", suspend_stats.total_hw_sleep);
+}
+static struct kobj_attribute total_hw_sleep = __ATTR_RO(total_hw_sleep);
+
static struct attribute *suspend_attrs[] = {
&success.attr,
&fail.attr,
@@ -391,12 +420,28 @@ static struct attribute *suspend_attrs[] = {
&last_failed_dev.attr,
&last_failed_errno.attr,
&last_failed_step.attr,
+ &last_hw_sleep.attr,
+ &total_hw_sleep.attr,
NULL,
};
+static umode_t suspend_attr_is_visible(struct kobject *kobj, struct attribute *attr, int idx)
+{
+ if (attr != &last_hw_sleep.attr &&
+ attr != &total_hw_sleep.attr)
+ return 0444;
+
+#ifdef CONFIG_ACPI
+ if (acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0)
+ return 0444;
+#endif
+ return 0;
+}
+
static const struct attribute_group suspend_attr_group = {
.name = "suspend_stats",
.attrs = suspend_attrs,
+ .is_visible = suspend_attr_is_visible,
};
#ifdef CONFIG_DEBUG_FS