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perf script python: Allow reporting the [un]throttle PERF_RECORD_ meta event

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perf_events may sometimes throttle an event due to creating too many
samples during a given timer tick.

As of now, the perf tool will not report on throttling, which means this
is a silent error.

Implement a callback for the throttle and unthrottle events within the
Python scripting engine, which can allow scripts to detect and report
when events may have been lost due to throttling.

The simplest script to report throttle events is:

  def throttle(*args):
      print("throttle" + repr(args))

  def unthrottle(*args):
      print("unthrottle" + repr(args))

Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210901210815.133251-1-stephen.s.brennan@oracle.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Stephen Brennan
2021-09-01 14:08:15 -07:00
committed by Arnaldo Carvalho de Melo
parent 71f7f897c3
commit 538d9c1829
3 changed files with 48 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
tools/perf/util/scripting-engines/trace-event-python.c
View File

@@ -1422,6 +1422,37 @@ static void python_process_event(union perf_event *event,
}
}
static void python_process_throttle(union perf_event *event,
struct perf_sample *sample,
struct machine *machine)
{
const char *handler_name;
PyObject *handler, *t;
if (event->header.type == PERF_RECORD_THROTTLE)
handler_name = "throttle";
else
handler_name = "unthrottle";
handler = get_handler(handler_name);
if (!handler)
return;
t = tuple_new(6);
if (!t)
return;
tuple_set_u64(t, 0, event->throttle.time);
tuple_set_u64(t, 1, event->throttle.id);
tuple_set_u64(t, 2, event->throttle.stream_id);
tuple_set_s32(t, 3, sample->cpu);
tuple_set_s32(t, 4, sample->pid);
tuple_set_s32(t, 5, sample->tid);
call_object(handler, t, handler_name);
Py_DECREF(t);
}
static void python_do_process_switch(union perf_event *event,
struct perf_sample *sample,
struct machine *machine)
@@ -2079,5 +2110,6 @@ struct scripting_ops python_scripting_ops = {
.process_auxtrace_error = python_process_auxtrace_error,
.process_stat = python_process_stat,
.process_stat_interval = python_process_stat_interval,
.process_throttle = python_process_throttle,
.generate_script = python_generate_script,
};