Telemetry: featurize tab_switching test for compressed swap performance

tools/perf/measurements/tab_switching.py

 # Copyright 2013 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.
 
 """The tab switching measurement.
 
 This measurement opens pages in different tabs. After all the tabs have opened,
 it cycles through each tab in sequence, and records a histogram of the time
 between when a tab was first requested to be shown, and when it was painted.
 Power usage is also measured.
 """
 
+import optparse

[aiolos (Not reviewing), 2015/04/03 18:16:39]

argparse should be used instead of optparse.

 import time
 
 from metrics import power
 from telemetry.core import util
 from telemetry.page import page_test
 from telemetry.value import histogram
 from telemetry.value import histogram_util
 
 # TODO: Revisit this test once multitab support is finalized.
 
 class TabSwitching(page_test.PageTest):
 
   # Amount of time to measure, in seconds.
   SAMPLE_TIME = 30
 
   def __init__(self):
     super(TabSwitching, self).__init__()
     self._first_page_in_pageset = True
     self._power_metric = None
 
+  @classmethod
+  def AddCommandLineArgs(cls, parser):

[aiolos (Not reviewing), 2015/04/03 18:16:39]

This shouldn't be specified via commandline arg.

+    group = optparse.OptionGroup(parser, 'Tab switching options')
+    group.add_option('--cycle-count',
+                     dest='cycle_count',
+                     default=1,
+                     type='int',
+                     help='Number of times the tab set is cycled through.')
+    # Use a high polling frequency throughout the test when checking for
+    # completion of a tab switch.  We may have to change this when running
+    # in a VM instrumented to get memory access statistics, because of the
+    # huge slowdown factor.
+    group.add_option('--poll-interval',
+                     dest='poll_interval',
+                     default=0.1,
+                     type='float',
+                     help='Poll interval when checking for completion '
+                     'of a tab switch.')
+    parser.add_option_group(group)
+
   def CustomizeBrowserOptions(self, options):
     options.AppendExtraBrowserArgs([
         '--enable-stats-collection-bindings'
     ])
     # Enable background networking so we can test its impact on power usage.
     options.disable_background_networking = False
     power.PowerMetric.CustomizeBrowserOptions(options)
 
   def WillStartBrowser(self, platform):
     self._first_page_in_pageset = True
@@ skipping 27 matching lines @@
       self._power_metric.Stop(page, tab)
       self._power_metric.AddResults(tab, results,)
 
     histogram_name = 'MPArch.RWH_TabSwitchPaintDuration'
     histogram_type = histogram_util.BROWSER_HISTOGRAM
     display_name = 'MPArch_RWH_TabSwitchPaintDuration'
     first_histogram = histogram_util.GetHistogram(
         histogram_type, histogram_name, tab)
     prev_histogram = first_histogram
 
-    for i in xrange(len(tab.browser.tabs)):
-      t = tab.browser.tabs[i]
-      t.Activate()
-      def _IsDone():
-        cur_histogram = histogram_util.GetHistogram(
+    for _ in xrange(self.options.cycle_count):
+      for i in xrange(len(tab.browser.tabs)):
+        t = tab.browser.tabs[i]
+        t.Activate()
+        def _IsDone():
+          cur_histogram = histogram_util.GetHistogram(
+              histogram_type, histogram_name, tab)
+          diff_histogram = histogram_util.SubtractHistogram(
+              cur_histogram, prev_histogram)
+          return diff_histogram.count != 0
+        # Use a fixed poll interval when detecting the completion of a
+        # tab switch to reduce variance as the system gets slow, for
+        # instance because of swapping.
+        util.WaitFor(
+            _IsDone, 30, fixed_poll_interval=self.options.poll_interval)
+        prev_histogram = histogram_util.GetHistogram(
             histogram_type, histogram_name, tab)
-        diff_histogram = histogram_util.SubtractHistogram(
-            cur_histogram, prev_histogram)
-        return diff_histogram
-      util.WaitFor(_IsDone, 30)
-      prev_histogram = histogram_util.GetHistogram(
-          histogram_type, histogram_name, tab)
 
     last_histogram = histogram_util.GetHistogram(
         histogram_type, histogram_name, tab)
     diff_histogram = histogram_util.SubtractHistogram(last_histogram,
         first_histogram)
 
     results.AddSummaryValue(
         histogram.HistogramValue(None, display_name, 'ms',
                                  raw_value_json=diff_histogram,
                                  important=False))