[PATCH v3] PM: sleep: Expose last succeeded resumed timestamp in sysfs

Masami Hiramatsu (Google)
2023-10-28T12:53:14Z

From: Masami Hiramatsu <mhiramat@kernel.org>

Expose last succeeded resumed timestamp as last_success_resume_time
attribute of suspend_stats in sysfs. This timestamp is recorded in
CLOCK_MONOTONIC. So user can find the actual resumed time and
measure the elapsed time from the time when the kernel finished
the resume to the user-space action (e.g. display the UI).

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Add (unsigned long long) casting for %llu.
- Add a line after last_success_resume_time_show().
Changes in v2:
- Use %llu instead of %lu for printing u64 value.
- Remove unneeded indent spaces from the last_success_resume_time
line in the debugfs suspend_stat file.
---
Documentation/ABI/testing/sysfs-power | 10 ++++++++++
include/linux/suspend.h | 2 ++
kernel/power/main.c | 15 +++++++++++++++
kernel/power/suspend.c | 1 +
4 files changed, 28 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power
index a3942b1036e2..63659765dee1 100644
--- a/Documentation/ABI/testing/sysfs-power
+++ b/Documentation/ABI/testing/sysfs-power
@@ -442,6 +442,16 @@ Description:
'total_hw_sleep' and 'last_hw_sleep' may not be accurate.
This number is measured in microseconds.

+What: /sys/power/suspend_stats/last_success_resume_time
+Date: Oct 2023
+Contact: Masami Hiramatsu <mhiramat@kernel.org>
+Description:
+ The /sys/power/suspend_stats/last_success_resume_time file
+ contains the timestamp of when the kernel successfully
+ resumed from suspend/hibernate.
+ This floating number is measured in seconds by monotonic
+ clock.
+
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 ef503088942d..ddd789044960 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -8,6 +8,7 @@
#include <linux/pm.h>
#include <linux/mm.h>
#include <linux/freezer.h>
+#include <linux/timekeeping.h>
#include <asm/errno.h>

#ifdef CONFIG_VT
@@ -71,6 +72,7 @@ struct suspend_stats {
u64 last_hw_sleep;
u64 total_hw_sleep;
u64 max_hw_sleep;
+ struct timespec64 last_success_resume_time;
enum suspend_stat_step failed_steps[REC_FAILED_NUM];
};

diff --git a/kernel/power/main.c b/kernel/power/main.c
index f6425ae3e8b0..2ab23fd3daac 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -421,6 +421,17 @@ 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_success_resume_time_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%llu.%llu\n",
+ (unsigned long long)suspend_stats.last_success_resume_time.tv_sec,
+ (unsigned long long)suspend_stats.last_success_resume_time.tv_nsec);
+}
+
+static struct kobj_attribute last_success_resume_time =
+ __ATTR_RO(last_success_resume_time);
+
static struct attribute *suspend_attrs[] = {
&success.attr,
&fail.attr,
@@ -438,6 +449,7 @@ static struct attribute *suspend_attrs[] = {
&last_hw_sleep.attr,
&total_hw_sleep.attr,
&max_hw_sleep.attr,
+ &last_success_resume_time.attr,
NULL,
};

@@ -514,6 +526,9 @@ static int suspend_stats_show(struct seq_file *s, void *unused)
suspend_step_name(
suspend_stats.failed_steps[index]));
}
+ seq_printf(s, "last_success_resume_time:\t%-llu.%llu\n",
+ (unsigned long long)suspend_stats.last_success_resume_time.tv_sec,
+ (unsigned long long)suspend_stats.last_success_resume_time.tv_nsec);

return 0;
}
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index fa3bf161d13f..33334565d5a6 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -622,6 +622,7 @@ int pm_suspend(suspend_state_t state)
dpm_save_failed_errno(error);
} else {
suspend_stats.success++;
+ ktime_get_ts64(&suspend_stats.last_success_resume_time);
}
pr_info("suspend exit\n");
return error;