Telemetry: More elegant histogram printing.

build/android/pylib/perf_tests_helper.py

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import re
 
 import android_commands
 import json
 import math
 
@@ skipping 85 matching lines @@
         _EscapePerfResult(measurement),
         trace_name,
         # Do not show equal sign if the trace is empty. Usually it happens when
         # measurement is enough clear to describe the result.
         '= ' if trace_name else '',
         value,
         units)
   else:
     assert(result_type in ['histogram', 'unimportant-histogram'])
     assert isinstance(values, list)
-    assert len(values)
-    # Print out each histogram separately. We can't print the units, otherwise
-    # the histogram json output can't be parsed easily.
-    output = ''
-    ix = 1
-    for value in values:
-      name = '%s.%s_%d' % (_EscapePerfResult(measurement), trace_name, ix)
-      output += '%s%s%s : %s = %s' % (
-          '\n' if ix > 1 else '',
-          RESULT_TYPES[result_type],
-          name,
-          name,
-          value)
-      ix += 1
-    measurement = '%s.%s' % (measurement, trace_name)
-    means_and_sds = [GeomMeanAndStdDevFromHistogram(value) for value in values]
-    _, avg, sd = _MeanAndStdDevFromList([mean for (mean, _) in means_and_sds ])
+    # The histograms can only be printed individually, there's no computation
+    # across different histograms.
+    assert len(values) == 1
+    value = values[0]
+    measurement += '.' + trace_name
+    output = '%s%s: %s=%s' % (
+        RESULT_TYPES[result_type],
+        _EscapePerfResult(measurement),
+        _EscapePerfResult(measurement),
+        value)
+    avg, sd = GeomMeanAndStdDevFromHistogram(value)
 
   if avg:
     output += '\nAvg %s: %f%s' % (measurement, avg, units)
   if sd:
     output += '\nSd  %s: %f%s' % (measurement, sd, units)
   if print_to_stdout:
     print output
   return output
 
 
@@ skipping 29 matching lines @@
   def TearDown(self):
     """Tears down performance tests."""
     if self._original_scaling_governor:
       self._SetScalingGovernorInternal(self._original_scaling_governor)
     self._original_scaling_governor = None
 
   def _SetScalingGovernorInternal(self, value):
     for cpu in range(self._num_cpus):
       self._adb.RunShellCommand(
           ('echo %s > ' + PerfTestSetup._SCALING_GOVERNOR) % (value, cpu))