[2/2,RFC,v2] PM-runtime: change the tracepoints to cover all usage_count
diff mbox series

Message ID 0a3ae7be4c467912327005995b1defb4fefd8101.1591600914.git.yu.c.chen@intel.com
State RFC, archived
Headers show
Series
  • Change trace point to cover all runtime usage count
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Commit Message

Chen Yu June 8, 2020, 7:42 a.m. UTC
Commit d229290689ae ("PM-runtime: add tracepoints for usage_count changes")
has added some tracepoints to monitor the change of runtime usage, and
there is something to improve:
1. There are some places that adjust the usage count have not
   been traced yet. For example, pm_runtime_get_noresume() and
   pm_runtime_put_noidle()
2. The change of the usage count will not be tracked if decreased
   from 1 to 0.

This patch intends to adjust the logic to be consistent with the
change of usage_counter, that is to say, only after the counter has
been possibly modified, we record it. Besides, all usage changes will
be shown using rpm_usage even if included by other trace points.
And these changes has helped track down the e1000e runtime issue.

Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
v2: According to Michal's suggestion, adjust the commit log
    to better describe the meaning of this patch.
--
 drivers/base/power/runtime.c | 38 +++++++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 14 deletions(-)

Comments

Michał Mirosław June 8, 2020, 7:50 a.m. UTC | #1
On Mon, Jun 08, 2020 at 03:42:15PM +0800, Chen Yu wrote:
> Commit d229290689ae ("PM-runtime: add tracepoints for usage_count changes")
> has added some tracepoints to monitor the change of runtime usage, and
> there is something to improve:
> 1. There are some places that adjust the usage count have not
>    been traced yet. For example, pm_runtime_get_noresume() and
>    pm_runtime_put_noidle()
> 2. The change of the usage count will not be tracked if decreased
>    from 1 to 0.
> 
> This patch intends to adjust the logic to be consistent with the
> change of usage_counter, that is to say, only after the counter has
> been possibly modified, we record it. Besides, all usage changes will
> be shown using rpm_usage even if included by other trace points.
> And these changes has helped track down the e1000e runtime issue.
> 
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> ---
> v2: According to Michal's suggestion, adjust the commit log
>     to better describe the meaning of this patch.
> --
>  drivers/base/power/runtime.c | 38 +++++++++++++++++++++++-------------
>  1 file changed, 24 insertions(+), 14 deletions(-)
[...]

Reviewed-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>

Patch
diff mbox series

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 85a248e196ca..5789d2624513 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1004,10 +1004,11 @@  int __pm_runtime_idle(struct device *dev, int rpmflags)
 	int retval;
 
 	if (rpmflags & RPM_GET_PUT) {
-		if (!atomic_dec_and_test(&dev->power.usage_count)) {
-			trace_rpm_usage_rcuidle(dev, rpmflags);
+		bool non_zero = !atomic_dec_and_test(&dev->power.usage_count);
+
+		trace_rpm_usage_rcuidle(dev, rpmflags);
+		if (non_zero)
 			return 0;
-		}
 	}
 
 	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
@@ -1038,10 +1039,12 @@  int __pm_runtime_suspend(struct device *dev, int rpmflags)
 	int retval;
 
 	if (rpmflags & RPM_GET_PUT) {
-		if (!atomic_dec_and_test(&dev->power.usage_count)) {
-			trace_rpm_usage_rcuidle(dev, rpmflags);
+		bool non_zero = !atomic_dec_and_test(&dev->power.usage_count);
+
+		trace_rpm_usage_rcuidle(dev, rpmflags);
+		if (non_zero)
 			return 0;
-		}
+
 	}
 
 	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
@@ -1073,8 +1076,10 @@  int __pm_runtime_resume(struct device *dev, int rpmflags)
 	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe &&
 			dev->power.runtime_status != RPM_ACTIVE);
 
-	if (rpmflags & RPM_GET_PUT)
+	if (rpmflags & RPM_GET_PUT) {
 		atomic_inc(&dev->power.usage_count);
+		trace_rpm_usage_rcuidle(dev, rpmflags);
+	}
 
 	spin_lock_irqsave(&dev->power.lock, flags);
 	retval = rpm_resume(dev, rpmflags);
@@ -1433,6 +1438,7 @@  void pm_runtime_forbid(struct device *dev)
 
 	dev->power.runtime_auto = false;
 	atomic_inc(&dev->power.usage_count);
+	trace_rpm_usage_rcuidle(dev, 0);
 	rpm_resume(dev, 0);
 
  out:
@@ -1448,16 +1454,17 @@  EXPORT_SYMBOL_GPL(pm_runtime_forbid);
  */
 void pm_runtime_allow(struct device *dev)
 {
+	bool is_zero;
+
 	spin_lock_irq(&dev->power.lock);
 	if (dev->power.runtime_auto)
 		goto out;
 
 	dev->power.runtime_auto = true;
-	if (atomic_dec_and_test(&dev->power.usage_count))
+	is_zero = atomic_dec_and_test(&dev->power.usage_count);
+	trace_rpm_usage_rcuidle(dev, RPM_AUTO | RPM_ASYNC);
+	if (is_zero)
 		rpm_idle(dev, RPM_AUTO | RPM_ASYNC);
-	else
-		trace_rpm_usage_rcuidle(dev, RPM_AUTO | RPM_ASYNC);
-
  out:
 	spin_unlock_irq(&dev->power.lock);
 }
@@ -1523,9 +1530,8 @@  static void update_autosuspend(struct device *dev, int old_delay, int old_use)
 		/* If it used to be allowed then prevent it. */
 		if (!old_use || old_delay >= 0) {
 			atomic_inc(&dev->power.usage_count);
-			rpm_resume(dev, 0);
-		} else {
 			trace_rpm_usage_rcuidle(dev, 0);
+			rpm_resume(dev, 0);
 		}
 	}
 
@@ -1533,8 +1539,10 @@  static void update_autosuspend(struct device *dev, int old_delay, int old_use)
 	else {
 
 		/* If it used to be prevented then allow it. */
-		if (old_use && old_delay < 0)
+		if (old_use && old_delay < 0) {
 			atomic_dec(&dev->power.usage_count);
+			trace_rpm_usage_rcuidle(dev, 0);
+		}
 
 		/* Maybe we can autosuspend now. */
 		rpm_idle(dev, RPM_AUTO);
@@ -1741,12 +1749,14 @@  void pm_runtime_drop_link(struct device *dev)
 void pm_runtime_get_noresume(struct device *dev)
 {
 	atomic_inc(&dev->power.usage_count);
+	trace_rpm_usage_rcuidle(dev, 0);
 }
 EXPORT_SYMBOL_GPL(pm_runtime_get_noresume);
 
 void pm_runtime_put_noidle(struct device *dev)
 {
 	atomic_add_unless(&dev->power.usage_count, -1, 0);
+	trace_rpm_usage_rcuidle(dev, 0);
 }
 EXPORT_SYMBOL_GPL(pm_runtime_put_noidle);