[PATCH v2] PM: runtime: add tracepoint for runtime_status changes
Existing runtime PM ftrace events (`rpm_suspend`, `rpm_resume`,
`rpm_return_int`) offer limited visibility into the exact timing of device
runtime power state transitions, particularly when asynchronous operations
are involved. When the `rpm_suspend` or `rpm_resume` functions are invoked
with the `RPM_ASYNC` flag, a return value of 0 i.e., success merely
indicates that the device power state request has been queued, not that
the device has yet transitioned.
A new ftrace event, `rpm_status`, is introduced. This event directly logs
the `power.runtime_status` value of a device whenever it changes providing
granular tracking of runtime power state transitions regardless of
synchronous or asynchronous `rpm_suspend` / `rpm_resume` usage.
Signed-off-by: Vilas Bhat
---
V1 -> V2: Modified enum value definition as per reviewer comments.
---
drivers/base/power/runtime.c | 1 +
include/trace/events/rpm.h | 42
2 files changed, 43 insertions(+)
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 05793c9fbb84..d10354847878 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -94,6 +94,7 @@ static void update_pm_runtime_accounting(struct device *dev)
static void __update_runtime_status(struct device *dev, enum rpm_status status)
{
update_pm_runtime_accounting(dev);
+ trace_rpm_status(dev, status);
dev->power.runtime_status = status;
}
diff --git a/include/trace/events/rpm.h b/include/trace/events/rpm.h
index 3c716214dab1..bd120e23ce12 100644
--- a/include/trace/events/rpm.h
+++ b/include/trace/events/rpm.h
@@ -101,6 +101,48 @@ TRACE_EVENT(rpm_return_int,
__entry->ret)
);
+#define RPM_STATUS_STRINGS \
+ EM(RPM_INVALID, "RPM_INVALID") \
+ EM(RPM_ACTIVE, "RPM_ACTIVE") \
+ EM(RPM_RESUMING, "RPM_RESUMING") \
+ EM(RPM_SUSPENDED, "RPM_SUSPENDED") \
+ EMe(RPM_SUSPENDING, "RPM_SUSPENDING")
+
+/* Enums require being exported to userspace, for user tool parsing. */
+#undef EM
+#undef EMe
+#define EM(a, b) TRACE_DEFINE_ENUM(a);
+#define EMe(a, b) TRACE_DEFINE_ENUM(a);
+
+RPM_STATUS_STRINGS
+
+/*
+ * Now redefine the EM() and EMe() macros to map the enums to the strings that
+ * will be printed in the output.
+ */
+#undef EM
+#undef EMe
+#define EM(a, b) { a, b },
+#define EMe(a, b) { a, b }
+
+TRACE_EVENT(rpm_status,
+ TP_PROTO(struct device *dev, enum rpm_status status),
+ TP_ARGS(dev, status),
+
+ TP_STRUCT__entry(
+ __string(name, dev_name(dev))
+ __field(int,status)
+ ),
+
+ TP_fast_assign(
+ __assign_str(name, dev_name(dev));
+ __entry->status = status;
+ ),
+
+ TP_printk("%s status=%s", __get_str(name),
+ __print_symbolic(__entry->status, RPM_STATUS_STRINGS))
+);
+
#endif /* _TRACE_RUNTIME_POWER_H */
/* This part must be outside protection */
--
2.44.0.rc0.258.g7320e95886-goog
Re: [PATCH v1] PM: runtime: add tracepoint for runtime_status changes
On Wed, Feb 21, 2024 at 10:33 AM Steven Rostedt wrote:
>
> On Wed, 21 Feb 2024 09:57:03 -0800
> Vilas Bhat wrote:
>
> > > You could do what everyone else does:
> > >
> > > #define RPM_STATUS_STRINGS \
> > > EM( RPM_INVALID, "RPM_INVALID" )\
> > > EM( RPM_ACTIVE, "RPM_ACTIVE" ) \
> > > EM( RPM_RESUMING, "RPM_RESUMING" ) \
> > > EM( RPM_SUSPENDED, "RPM_SUSPENDED" )\
> > > EMe( RPM_SUSPENDING, "RPM_SUSPENDING" )
> > >
> > > #undef EM
> > > #undef EMe
> > > #define EM(a, b)TRACE_DEFINE_ENUM(a);
> > > #define EMe(a, b) TRACE_DEFINE_ENUM(a);
> > >
> > > RPM_STATUS_STRINGS
> > >
> > > #undef EM
> > > #undef EMe
> > > #define EM(a, b){ a, b },
> > > #define EMe(a, b) { a, b }
> > >
> >
> > Thanks for the comment, Steven. I did notice both methods of defining
> > enum values for tracepoints and chose this method because it felt
> > clearer. Could you clarify on why the method you suggested is
> > preferred?
> >
>
> Sure. One big reason: It removes duplication.
>
> If you add another enum to the list, you only need to update it in one
> place. And it prevents the two from getting out of sync.
>
> -- Steve
That makes sense! Thanks. I will revise the patch and send a new version soon.
Re: [PATCH v1] PM: runtime: add tracepoint for runtime_status changes
On Wed, Feb 21, 2024 at 9:12 AM Steven Rostedt wrote:
>
> On Wed, 21 Feb 2024 16:41:10 +0000
> Vilas Bhat wrote:
>
>
> > diff --git a/include/trace/events/rpm.h b/include/trace/events/rpm.h
> > index 3c716214dab1..f1dc4e95dbce 100644
> > --- a/include/trace/events/rpm.h
> > +++ b/include/trace/events/rpm.h
> > @@ -101,6 +101,42 @@ TRACE_EVENT(rpm_return_int,
> > __entry->ret)
> > );
> >
> > +#define RPM_STATUS_STRINGS \
> > + { RPM_INVALID, "RPM_INVALID" }, \
> > + { RPM_ACTIVE, "RPM_ACTIVE" }, \
> > + { RPM_RESUMING, "RPM_RESUMING" }, \
> > + { RPM_SUSPENDED, "RPM_SUSPENDED" }, \
> > + { RPM_SUSPENDING, "RPM_SUSPENDING" }
> > +
> > +/*
> > + * ftrace's __print_symbolic requires that all enum values be wrapped in
> > the
> > + * TRACE_DEFINE_ENUM macro so that the enum value can be encoded in the
> > ftrace
> > + * ring buffer.
> > + */
> > +TRACE_DEFINE_ENUM(RPM_INVALID);
> > +TRACE_DEFINE_ENUM(RPM_ACTIVE);
> > +TRACE_DEFINE_ENUM(RPM_RESUMING);
> > +TRACE_DEFINE_ENUM(RPM_SUSPENDED);
> > +TRACE_DEFINE_ENUM(RPM_SUSPENDING);
>
> You could do what everyone else does:
>
> #define RPM_STATUS_STRINGS \
> EM( RPM_INVALID, "RPM_INVALID" )\
> EM( RPM_ACTIVE, "RPM_ACTIVE" ) \
> EM( RPM_RESUMING, "RPM_RESUMING" ) \
> EM( RPM_SUSPENDED, "RPM_SUSPENDED" )\
> EMe( RPM_SUSPENDING, "RPM_SUSPENDING" )
>
> #undef EM
> #undef EMe
> #define EM(a, b)TRACE_DEFINE_ENUM(a);
> #define EMe(a, b) TRACE_DEFINE_ENUM(a);
>
> RPM_STATUS_STRINGS
>
> #undef EM
> #undef EMe
> #define EM(a, b){ a, b },
> #define EMe(a, b) { a, b }
>
Thanks for the comment, Steven. I did notice both methods of defining
enum values for tracepoints and chose this method because it felt
clearer. Could you clarify on why the method you suggested is
preferred?
> > +
> > +TRACE_EVENT(rpm_status,
> > + TP_PROTO(struct device *dev, enum rpm_status status),
> > + TP_ARGS(dev, status),
> > +
> > + TP_STRUCT__entry(
> > + __string(name, dev_name(dev))
> > + __field(int,status)
> > + ),
> > +
> > + TP_fast_assign(
> > + __assign_str(name, dev_name(dev));
> > + __entry->status = status;
> > + ),
> > +
> > + TP_printk("%s status=%s", __get_str(name),
> > + __print_symbolic(__entry->status, RPM_STATUS_STRINGS))
>
> This will be what you want with that last redefine of EM*()
>
> -- Steve
>
>
> > +);
> > +
> > #endif /* _TRACE_RUNTIME_POWER_H */
> >
> > /* This part must be outside protection */
>
[PATCH v1] PM: runtime: add tracepoint for runtime_status changes
Existing runtime PM ftrace events (`rpm_suspend`, `rpm_resume`,
`rpm_return_int`) offer limited visibility into the exact timing of device
runtime power state transitions, particularly when asynchronous operations
are involved. When the `rpm_suspend` or `rpm_resume` functions are invoked
with the `RPM_ASYNC` flag, a return value of 0 i.e., success merely
indicates that the device power state request has been queued, not that
the device has yet transitioned.
A new ftrace event, `rpm_status`, is introduced. This event directly logs
the `power.runtime_status` value of a device whenever it changes providing
granular tracking of runtime power state transitions regardless of
synchronous or asynchronous `rpm_suspend` / `rpm_resume` usage.
Signed-off-by: Vilas Bhat
---
drivers/base/power/runtime.c | 1 +
include/trace/events/rpm.h | 36
2 files changed, 37 insertions(+)
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 05793c9fbb84..d10354847878 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -94,6 +94,7 @@ static void update_pm_runtime_accounting(struct device *dev)
static void __update_runtime_status(struct device *dev, enum rpm_status status)
{
update_pm_runtime_accounting(dev);
+ trace_rpm_status(dev, status);
dev->power.runtime_status = status;
}
diff --git a/include/trace/events/rpm.h b/include/trace/events/rpm.h
index 3c716214dab1..f1dc4e95dbce 100644
--- a/include/trace/events/rpm.h
+++ b/include/trace/events/rpm.h
@@ -101,6 +101,42 @@ TRACE_EVENT(rpm_return_int,
__entry->ret)
);
+#define RPM_STATUS_STRINGS \
+ { RPM_INVALID, "RPM_INVALID" }, \
+ { RPM_ACTIVE, "RPM_ACTIVE" }, \
+ { RPM_RESUMING, "RPM_RESUMING" }, \
+ { RPM_SUSPENDED, "RPM_SUSPENDED" }, \
+ { RPM_SUSPENDING, "RPM_SUSPENDING" }
+
+/*
+ * ftrace's __print_symbolic requires that all enum values be wrapped in the
+ * TRACE_DEFINE_ENUM macro so that the enum value can be encoded in the ftrace
+ * ring buffer.
+ */
+TRACE_DEFINE_ENUM(RPM_INVALID);
+TRACE_DEFINE_ENUM(RPM_ACTIVE);
+TRACE_DEFINE_ENUM(RPM_RESUMING);
+TRACE_DEFINE_ENUM(RPM_SUSPENDED);
+TRACE_DEFINE_ENUM(RPM_SUSPENDING);
+
+TRACE_EVENT(rpm_status,
+ TP_PROTO(struct device *dev, enum rpm_status status),
+ TP_ARGS(dev, status),
+
+ TP_STRUCT__entry(
+ __string(name, dev_name(dev))
+ __field(int,status)
+ ),
+
+ TP_fast_assign(
+ __assign_str(name, dev_name(dev));
+ __entry->status = status;
+ ),
+
+ TP_printk("%s status=%s", __get_str(name),
+ __print_symbolic(__entry->status, RPM_STATUS_STRINGS))
+);
+
#endif /* _TRACE_RUNTIME_POWER_H */
/* This part must be outside protection */
--
2.44.0.rc0.258.g7320e95886-goog
