Telemetry: Use mimimum tracing for timeline benchmarks.

tools/perf/metrics/timeline.py

Index: tools/perf/metrics/timeline.py
diff --git a/tools/perf/metrics/timeline.py b/tools/perf/metrics/timeline.py
index 3442cab15b01b00604f22a2541f4df74825a0c7f..90033d188768bd6ad88692ca7f68c85146114782 100644
--- a/tools/perf/metrics/timeline.py
+++ b/tools/perf/metrics/timeline.py
@@ -11,6 +11,17 @@ from telemetry.page import page_measurement
 TRACING_MODE = 'tracing-mode'
 TIMELINE_MODE = 'timeline-mode'
 
+# All tracing categories not disabled-by-default
+DEFAULT_TRACE_CATEGORIES = None
+
+# Categories for absolute minimum overhead tracing. This contains no
+# sub-traces of thread tasks, so it's only useful for capturing the
+# cpu-time spent on threads (as well as needed benchmark traces)
+# "disabled-by-default-topall,"

[ernstm, 2014/02/19 22:18:16]

In the comment: disabled-by-default-topall -> disabled-by-default-poll_cpu
Maybe we could just put this event into the 'benchmark' category?

+MINIMAL_TRACE_CATEGORIES = ("disabled-by-default-poll_cpu,"
+                            "benchmark,"
+                            "webkit.console,"
+                            "trace_event_overhead")
 
 class MissingFramesError(page_measurement.MeasurementFailure):
   def __init__(self):
@@ -24,6 +35,7 @@ class TimelineMetric(Metric):
     """
     super(TimelineMetric, self).__init__()
     assert mode in (TRACING_MODE, TIMELINE_MODE)
+    self.trace_categories = DEFAULT_TRACE_CATEGORIES
     self._mode = mode
     self._model = None
     self._renderer_process = None
@@ -39,7 +51,7 @@ class TimelineMetric(Metric):
     if self._mode == TRACING_MODE:
       if not tab.browser.supports_tracing:
         raise Exception('Not supported')
-      tab.browser.StartTracing()
+      tab.browser.StartTracing(self.trace_categories)
     else:
       assert self._mode == TIMELINE_MODE
       tab.StartTimelineRecording()
@@ -281,8 +293,29 @@ class ResultsForThread(object):
 class ThreadTimesTimelineMetric(TimelineMetric):
   def __init__(self):
     super(ThreadTimesTimelineMetric, self).__init__(TRACING_MODE)
-    self.results_to_report = AllThreads
-    self.details_to_report = NoThreads
+    # Minimal traces, for minimum noise in CPU-time measurements.
+    self.trace_categories = MINIMAL_TRACE_CATEGORIES
+    self._results_to_report = AllThreads
+    self._details_to_report = NoThreads
+
+  @property
+  def results_to_report(self):
+    return self._results_to_report
+
+  @results_to_report.setter
+  def results_to_report(self, results_to_report):
+    self._results_to_report = results_to_report
+
+  @property
+  def details_to_report(self):
+    return self._details_to_report
+
+  @details_to_report.setter
+  def details_to_report(self, details_to_report):
+    self._details_to_report = details_to_report
+    # We need the other traces in order to have any details to report.
+    if not details_to_report == NoThreads:
+      self.trace_categories = DEFAULT_TRACE_CATEGORIES
 
   def CountSlices(self, slices, substring):
     count = 0
@@ -322,9 +355,9 @@ class ThreadTimesTimelineMetric(TimelineMetric):
 
     # Report the desired results and details.
     for thread_results in thread_category_results.values():
-      if thread_results.name in self.results_to_report:
+      if thread_results.name in self._results_to_report:
         thread_results.AddResults(num_frames, results)
       # TOOD(nduca): When generic results objects are done, this special case
       # can be replaced with a generic UI feature.
-      if thread_results.name in self.details_to_report:
+      if thread_results.name in self._details_to_report:
         thread_results.AddDetailedResults(num_frames, results)