Remove needless ')' and put replace line with code block. CC: Randy Dunlap <[email protected]> Suggested-by: Steven Rostedt <[email protected]> Signed-off-by: Manuel Ebner <[email protected]> --- @ Steven, sorry, I coudn't figure out how to implement your suggestions from [v2]
[v3] remove line with similar content as code block. [v2] add paragraph and code block. https://lore.kernel.org/all/[email protected]/ [v1] https://lore.kernel.org/all/[email protected]/ --- Documentation/trace/histogram-design.rst | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/Documentation/trace/histogram-design.rst b/Documentation/trace/histogram-design.rst index 41a726cd3..5c5748928 100644 --- a/Documentation/trace/histogram-design.rst +++ b/Documentation/trace/histogram-design.rst @@ -876,9 +876,8 @@ next_pid field on this sched_switch event, we retrieve the variables specified in the wakeup_latency() trace action, and use them to generate a new wakeup_latency event into the trace stream. -Note that the way the trace handlers such as wakeup_latency() (which -could equivalently be written trace(wakeup_latency,$wakeup_lat,next_pid) -are implemented, the parameters specified to the trace handler must be +Note that the way the trace handlers such as wakeup_latency() are +implemented, the parameters specified to the trace handler must be variables. In this case, $wakeup_lat is obviously a variable, but next_pid isn't, since it's just naming a field in the sched_switch trace event. Since this is something that almost every trace() and @@ -916,6 +915,13 @@ means it will be automatically converted into a field variable:: onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,next_pid)' >> /sys/kernel/tracing/events/sched/sched_switch/trigger +Note that the above is the old way to trigger a synthetic event, whereas the +newer way is preferred, which uses the trace() action handler:: + + # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0: \ + onmatch(sched.sched_waking).trace(wakeup_latency,$wakeup_lat,next_pid)' >> + /sys/kernel/tracing/events/sched/sched_switch/trigger + The diagram for the sched_switch event is similar to previous examples but shows the additional field_vars[] array for hist_data and shows the linkages between the field_vars and the variables and references -- 2.55.0
