See Documentation/trace/histogram.rst for details and examples.
-6.3 In-kernel trace event API
------------------------------
+7. In-kernel trace event API
+============================
In most cases, the command-line interface to trace events is more than
sufficient. Sometimes, however, applications might find the need for
- tracing synthetic events from in-kernel code
- the low-level "dynevent_cmd" API
-6.3.1 Dyamically creating synthetic event definitions
------------------------------------------------------
+7.1 Dyamically creating synthetic event definitions
+---------------------------------------------------
There are a couple ways to create a new synthetic event from a kernel
module or other kernel code.
At this point, the event object is ready to be used for tracing new
events.
-6.3.3 Tracing synthetic events from in-kernel code
---------------------------------------------------
+7.2 Tracing synthetic events from in-kernel code
+------------------------------------------------
To trace a synthetic event, there are several options. The first
option is to trace the event in one call, using synth_event_trace()
synth_event_add_next_val() or synth_event_add_val() to add the values
piecewise.
-6.3.3.1 Tracing a synthetic event all at once
----------------------------------------------
+7.2.1 Tracing a synthetic event all at once
+-------------------------------------------
To trace a synthetic event all at once, the synth_event_trace() or
synth_event_trace_array() functions can be used.
ret = synth_event_delete("schedtest");
-6.3.3.1 Tracing a synthetic event piecewise
--------------------------------------------
+7.2.2 Tracing a synthetic event piecewise
+-----------------------------------------
To trace a synthetic using the piecewise method described above, the
synth_event_trace_start() function is used to 'open' the synthetic
of whether any of the add calls failed (say due to a bad field name
being passed in).
-6.3.4 Dyamically creating kprobe and kretprobe event definitions
-----------------------------------------------------------------
+7.3 Dyamically creating kprobe and kretprobe event definitions
+--------------------------------------------------------------
To create a kprobe or kretprobe trace event from kernel code, the
kprobe_event_gen_cmd_start() or kretprobe_event_gen_cmd_start()
ret = kprobe_event_delete("gen_kprobe_test");
-6.3.4 The "dynevent_cmd" low-level API
---------------------------------------
+7.4 The "dynevent_cmd" low-level API
+------------------------------------
Both the in-kernel synthetic event and kprobe interfaces are built on
top of a lower-level "dynevent_cmd" interface. This interface is