[PATCH 9] PM: Measure device suspend and resume times (was: Re: [PATCH 0/6] PM: Asynchronous suspend and resume of devices)

Rafael J. Wysocki
2009-08-29T19:22:04Z

On Wednesday 26 August 2009, Rafael J. Wysocki wrote:
> Hi,
>
> The following patches introduce a mechanism allowing us to execute device
> drivers' suspend and resume callbacks asynchronously during system sleep
> transitions, such as suspend to RAM.
>
> The idea is explained in the changelogs of the first two patches.
>
> Comments welcome.

I have one more patch that adds time measurements to the code in
drivers/base/power/main.c, so that one can easily see how much these operations
take.

Thanks,
Rafael

---
From: Rafael J. Wysocki <rjw@sisk.pl>
Subject: PM: Measure device suspend and resume times

Measure and print the time of suspending and resuming all devices.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
drivers/base/power/main.c | 56 +++++++++++++++++++++++++++++++++++++++++++++-
include/linux/pm.h | 3 ++
kernel/power/swsusp.c | 6 ----
3 files changed, 59 insertions(+), 6 deletions(-)

Index: linux-2.6/kernel/power/swsusp.c
===================================================================
--- linux-2.6.orig/kernel/power/swsusp.c
+++ linux-2.6/kernel/power/swsusp.c
@@ -169,14 +169,10 @@ int swsusp_swap_in_use(void)
void swsusp_show_speed(struct timeval *start, struct timeval *stop,
unsigned nr_pages, char *msg)
{
- s64 elapsed_centisecs64;
- int centisecs;
+ int centisecs = pm_time_elapsed(start, stop);
int k;
int kps;

- elapsed_centisecs64 = timeval_to_ns(stop) - timeval_to_ns(start);
- do_div(elapsed_centisecs64, NSEC_PER_SEC / 100);
- centisecs = elapsed_centisecs64;
if (centisecs == 0)
centisecs = 1; /* avoid div-by-zero */
k = nr_pages * (PAGE_SIZE / 1024);
Index: linux-2.6/drivers/base/power/main.c
===================================================================
--- linux-2.6.orig/drivers/base/power/main.c
+++ linux-2.6/drivers/base/power/main.c
@@ -28,6 +28,7 @@
#include <linux/interrupt.h>
#include <linux/async.h>
#include <linux/completion.h>
+#include <linux/time.h>

#include "../base.h"
#include "power.h"
@@ -434,6 +435,20 @@ static bool pm_op_started(struct device
return ret;
}

+/**
+ * pm_time_elapsed - Compute time elapsed between two timestamps.
+ * @start: First timestamp.
+ * @stop: Second timestamp.
+ */
+int pm_time_elapsed(struct timeval *start, struct timeval *stop)
+{
+ s64 elapsed_centisecs64;
+
+ elapsed_centisecs64 = timeval_to_ns(stop) - timeval_to_ns(start);
+ do_div(elapsed_centisecs64, NSEC_PER_SEC / 100);
+ return elapsed_centisecs64;
+}
+
static char *pm_verb(int event)
{
switch (event) {
@@ -458,6 +473,16 @@ static char *pm_verb(int event)
}
}

+static void dpm_show_time(struct timeval *start, struct timeval *stop,
+ pm_message_t state, const char *info)
+{
+ int centisecs = pm_time_elapsed(start, stop);
+
+ printk(KERN_INFO "PM: %s%s%s of devices complete in %d.%02d seconds\n",
+ info ? info : "", info ? " " : "", pm_verb(state.event),
+ centisecs / 100, centisecs % 100);
+}
+
static void pm_dev_dbg(struct device *dev, pm_message_t state, char *info)
{
dev_dbg(dev, "%s%s%s\n", info, pm_verb(state.event),
@@ -580,6 +605,9 @@ static int device_resume_noirq(struct de
void dpm_resume_noirq(pm_message_t state)
{
struct device *dev;
+ struct timeval start, stop;
+
+ do_gettimeofday(&start);

mutex_lock(&dpm_list_mtx);
transition_started = false;
@@ -595,6 +623,10 @@ void dpm_resume_noirq(pm_message_t state
}
dpm_synchronize_noirq();
mutex_unlock(&dpm_list_mtx);
+
+ do_gettimeofday(&stop);
+ dpm_show_time(&start, &stop, state, "EARLY");
+
resume_device_irqs();
}
EXPORT_SYMBOL_GPL(dpm_resume_noirq);
@@ -740,6 +772,9 @@ static int device_resume(struct device *
static void dpm_resume(pm_message_t state)
{
struct list_head list;
+ struct timeval start, stop;
+
+ do_gettimeofday(&start);

INIT_LIST_HEAD(&list);
mutex_lock(&dpm_list_mtx);
@@ -770,6 +805,9 @@ static void dpm_resume(pm_message_t stat
list_splice(&list, &dpm_list);
mutex_unlock(&dpm_list_mtx);
dpm_synchronize();
+
+ do_gettimeofday(&stop);
+ dpm_show_time(&start, &stop, state, NULL);
}

/**
@@ -985,8 +1023,11 @@ static int device_suspend_noirq(struct d
int dpm_suspend_noirq(pm_message_t state)
{
struct device *dev;
+ struct timeval start, stop;
int error = 0;

+ do_gettimeofday(&start);
+
suspend_device_irqs();
mutex_lock(&dpm_list_mtx);
pm_transition = state;
@@ -1004,8 +1045,12 @@ int dpm_suspend_noirq(pm_message_t state
}
dpm_synchronize_noirq();
mutex_unlock(&dpm_list_mtx);
- if (error)
+ if (error) {
dpm_resume_noirq(resume_event(state));
+ } else {
+ do_gettimeofday(&stop);
+ dpm_show_time(&start, &stop, state, "LATE");
+ }
return error;
}
EXPORT_SYMBOL_GPL(dpm_suspend_noirq);
@@ -1157,8 +1202,11 @@ static int device_suspend(struct device
static int dpm_suspend(pm_message_t state)
{
struct list_head list;
+ struct timeval start, stop;
int error = 0;

+ do_gettimeofday(&start);
+
INIT_LIST_HEAD(&list);
mutex_lock(&dpm_list_mtx);
pm_transition = state;
@@ -1188,6 +1236,12 @@ static int dpm_suspend(pm_message_t stat
list_splice(&list, dpm_list.prev);
mutex_unlock(&dpm_list_mtx);
dpm_synchronize();
+
+ if (!error) {
+ do_gettimeofday(&stop);
+ dpm_show_time(&start, &stop, state, NULL);
+ }
+
return error;
}

Index: linux-2.6/include/linux/pm.h
===================================================================
--- linux-2.6.orig/include/linux/pm.h
+++ linux-2.6/include/linux/pm.h
@@ -505,6 +505,9 @@ extern int sysdev_suspend(pm_message_t s
extern int dpm_suspend_noirq(pm_message_t state);
extern int dpm_suspend_start(pm_message_t state);

+struct timeval;
+extern int pm_time_elapsed(struct timeval *start, struct timeval *stop);
+
extern void __suspend_report_result(const char *function, void *fn, int ret);

#define suspend_report_result(fn, ret) \