The current trace documentation, the section describing histogram's "onmatch"
is not straightforward enough about how this action is applied. It is not
clear what criteria are used to "match" both events. A short note is added,
describing what exactly is compared in order to match the events.
Signed-off-by: Tzvetomir Stoyanov <[email protected]>
---
Documentation/trace/histogram.txt | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/Documentation/trace/histogram.txt b/Documentation/trace/histogram.txt
index 7ffea6aa22e3..d97f0530a731 100644
--- a/Documentation/trace/histogram.txt
+++ b/Documentation/trace/histogram.txt
@@ -1863,7 +1863,10 @@ hist trigger specification.
The 'matching.event' specification is simply the fully qualified
event name of the event that matches the target event for the
- onmatch() functionality, in the form 'system.event_name'.
+ onmatch() functionality, in the form 'system.event_name'. Histogram
+ keys of both events are compared to find if events match. In the case
+ multiple histogram keys are used, both events must have the same
+ number of keys, and the keys must match in the same order.
Finally, the number and type of variables/fields in the 'param
list' must match the number and types of the fields in the
@@ -1920,9 +1923,10 @@ hist trigger specification.
/sys/kernel/debug/tracing/events/sched/sched_waking/trigger
Then, when the corresponding thread is actually scheduled onto the
- CPU by a sched_switch event, calculate the latency and use that
- along with another variable and an event field to generate a
- wakeup_latency synthetic event:
+ CPU by a sched_switch event (where the sched_waking key "saved_pid"
+ matches the sched_switch key "next_pid"), calculate the latency and
+ use that along with another variable and an event field to generate
+ a wakeup_latency synthetic event:
# echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:\
onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,\
--
2.21.0
Tom,
Can you review this patch.
Jon,
After Tom gives his review, can you take this in your tree?
Thanks!
Reviewed-by: Steven Rostedt (VMware) <[email protected]>
-- Steve
On Tue, 7 May 2019 17:49:46 +0300
Tzvetomir Stoyanov <[email protected]> wrote:
> The current trace documentation, the section describing histogram's "onmatch"
> is not straightforward enough about how this action is applied. It is not
> clear what criteria are used to "match" both events. A short note is added,
> describing what exactly is compared in order to match the events.
>
> Signed-off-by: Tzvetomir Stoyanov <[email protected]>
> ---
> Documentation/trace/histogram.txt | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/trace/histogram.txt b/Documentation/trace/histogram.txt
> index 7ffea6aa22e3..d97f0530a731 100644
> --- a/Documentation/trace/histogram.txt
> +++ b/Documentation/trace/histogram.txt
> @@ -1863,7 +1863,10 @@ hist trigger specification.
>
> The 'matching.event' specification is simply the fully qualified
> event name of the event that matches the target event for the
> - onmatch() functionality, in the form 'system.event_name'.
> + onmatch() functionality, in the form 'system.event_name'. Histogram
> + keys of both events are compared to find if events match. In the case
> + multiple histogram keys are used, both events must have the same
> + number of keys, and the keys must match in the same order.
>
> Finally, the number and type of variables/fields in the 'param
> list' must match the number and types of the fields in the
> @@ -1920,9 +1923,10 @@ hist trigger specification.
> /sys/kernel/debug/tracing/events/sched/sched_waking/trigger
>
> Then, when the corresponding thread is actually scheduled onto the
> - CPU by a sched_switch event, calculate the latency and use that
> - along with another variable and an event field to generate a
> - wakeup_latency synthetic event:
> + CPU by a sched_switch event (where the sched_waking key "saved_pid"
> + matches the sched_switch key "next_pid"), calculate the latency and
> + use that along with another variable and an event field to generate
> + a wakeup_latency synthetic event:
>
> # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:\
> onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,\
Hi Steve,
On Tue, 2019-05-07 at 20:11 -0400, Steven Rostedt wrote:
> Tom,
>
> Can you review this patch.
>
Sure.
> Jon,
>
> After Tom gives his review, can you take this in your tree?
>
> Thanks!
>
> Reviewed-by: Steven Rostedt (VMware) <[email protected]>
>
Reviewed-by: Tom Zanussi <[email protected]>
Thanks,
Tom
> -- Steve
>
>
> On Tue, 7 May 2019 17:49:46 +0300
> Tzvetomir Stoyanov <[email protected]> wrote:
>
> > The current trace documentation, the section describing histogram's
> > "onmatch"
> > is not straightforward enough about how this action is applied. It
> > is not
> > clear what criteria are used to "match" both events. A short note
> > is added,
> > describing what exactly is compared in order to match the events.
> >
> > Signed-off-by: Tzvetomir Stoyanov <[email protected]>
> > ---
> > Documentation/trace/histogram.txt | 12 ++++++++----
> > 1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/Documentation/trace/histogram.txt
> > b/Documentation/trace/histogram.txt
> > index 7ffea6aa22e3..d97f0530a731 100644
> > --- a/Documentation/trace/histogram.txt
> > +++ b/Documentation/trace/histogram.txt
> > @@ -1863,7 +1863,10 @@ hist trigger specification.
> >
> > The 'matching.event' specification is simply the fully
> > qualified
> > event name of the event that matches the target event for the
> > - onmatch() functionality, in the form 'system.event_name'.
> > + onmatch() functionality, in the form 'system.event_name'.
> > Histogram
> > + keys of both events are compared to find if events match. In
> > the case
> > + multiple histogram keys are used, both events must have the
> > same
> > + number of keys, and the keys must match in the same order.
> >
> > Finally, the number and type of variables/fields in the 'param
> > list' must match the number and types of the fields in the
> > @@ -1920,9 +1923,10 @@ hist trigger specification.
> > /sys/kernel/debug/tracing/events/sched/sched_waking/tr
> > igger
> >
> > Then, when the corresponding thread is actually scheduled onto
> > the
> > - CPU by a sched_switch event, calculate the latency and use
> > that
> > - along with another variable and an event field to generate a
> > - wakeup_latency synthetic event:
> > + CPU by a sched_switch event (where the sched_waking key
> > "saved_pid"
> > + matches the sched_switch key "next_pid"), calculate the
> > latency and
> > + use that along with another variable and an event field to
> > generate
> > + a wakeup_latency synthetic event:
> >
> > # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-
> > $ts0:\
> > onmatch(sched.sched_waking).wakeup_latency($wakeup_lat
> > ,\
>
>
On Wed, 8 May 2019 12:18:54 -0400
Steven Rostedt <[email protected]> wrote:
> Jon,
>
> Can you take this patch in your tree?
Will do.
jon
Jon,
Can you take this patch in your tree?
Tom,
Thanks for the review!
-- Steve
On Wed, 08 May 2019 08:15:26 -0500
Tom Zanussi <[email protected]> wrote:
> Hi Steve,
>
> On Tue, 2019-05-07 at 20:11 -0400, Steven Rostedt wrote:
> > Tom,
> >
> > Can you review this patch.
> >
>
> Sure.
>
> > Jon,
> >
> > After Tom gives his review, can you take this in your tree?
> >
> > Thanks!
> >
> > Reviewed-by: Steven Rostedt (VMware) <[email protected]>
> >
>
> Reviewed-by: Tom Zanussi <[email protected]>
>
> Thanks,
>
> Tom
>
> > -- Steve
> >
> >
> > On Tue, 7 May 2019 17:49:46 +0300
> > Tzvetomir Stoyanov <[email protected]> wrote:
> >
> > > The current trace documentation, the section describing histogram's
> > > "onmatch"
> > > is not straightforward enough about how this action is applied. It
> > > is not
> > > clear what criteria are used to "match" both events. A short note
> > > is added,
> > > describing what exactly is compared in order to match the events.
> > >
> > > Signed-off-by: Tzvetomir Stoyanov <[email protected]>
> > > ---
> > > Documentation/trace/histogram.txt | 12 ++++++++----
> > > 1 file changed, 8 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/Documentation/trace/histogram.txt
> > > b/Documentation/trace/histogram.txt
> > > index 7ffea6aa22e3..d97f0530a731 100644
> > > --- a/Documentation/trace/histogram.txt
> > > +++ b/Documentation/trace/histogram.txt
> > > @@ -1863,7 +1863,10 @@ hist trigger specification.
> > >
> > > The 'matching.event' specification is simply the fully
> > > qualified
> > > event name of the event that matches the target event for the
> > > - onmatch() functionality, in the form 'system.event_name'.
> > > + onmatch() functionality, in the form 'system.event_name'.
> > > Histogram
> > > + keys of both events are compared to find if events match. In
> > > the case
> > > + multiple histogram keys are used, both events must have the
> > > same
> > > + number of keys, and the keys must match in the same order.
> > >
> > > Finally, the number and type of variables/fields in the 'param
> > > list' must match the number and types of the fields in the
> > > @@ -1920,9 +1923,10 @@ hist trigger specification.
> > > /sys/kernel/debug/tracing/events/sched/sched_waking/tr
> > > igger
> > >
> > > Then, when the corresponding thread is actually scheduled onto
> > > the
> > > - CPU by a sched_switch event, calculate the latency and use
> > > that
> > > - along with another variable and an event field to generate a
> > > - wakeup_latency synthetic event:
> > > + CPU by a sched_switch event (where the sched_waking key
> > > "saved_pid"
> > > + matches the sched_switch key "next_pid"), calculate the
> > > latency and
> > > + use that along with another variable and an event field to
> > > generate
> > > + a wakeup_latency synthetic event:
> > >
> > > # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-
> > > $ts0:\
> > > onmatch(sched.sched_waking).wakeup_latency($wakeup_lat
> > > ,\
> >
> >