New Cpu metric that calculates avg cpu_load of the browser over a span of time using browser.cpu_stats. Added this metric to tab_switching measurement to get idle-cpu usage of the browser

TEST=tools/perf/run_measurement tab_switching tools/perf/page_sets/top_10.json

BUG=264075

Review URL: https://chromiumcodereview.appspot.com/23645006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@222303 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 78 insertions, 2 deletions

diff --git a/tools/perf/measurements/tab_switching.py b/tools/perf/measurements/tab_switching.py
index 19eb1de..6342673 100644
--- a/tools/perf/measurements/tab_switching.py
+++ b/tools/perf/measurements/tab_switching.py
@@ -9,6 +9,9 @@ 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.
 """
 
+import time
+
+from metrics import cpu
 from metrics import histogram_util
 from telemetry.core import util
 from telemetry.page import page_measurement
@@ -17,6 +20,10 @@ from telemetry.page import page_runner
 # TODO: Revisit this test once multitab support is finalized.
 
 class TabSwitching(page_measurement.PageMeasurement):
+  def __init__(self):
+    super(TabSwitching, self).__init__()
+    self._cpu_metric = None
+
   def CustomizeBrowserOptions(self, options):
     options.AppendExtraBrowserArgs([
         '--enable-stats-collection-bindings',
@@ -24,6 +31,9 @@ class TabSwitching(page_measurement.PageMeasurement):
         '--reduce-security-for-dom-automation-tests'
     ])
 
+  def DidStartBrowser(self, browser):
+    self._cpu_metric = cpu.Cpu(browser)
+
   def CanRunForPage(self, page):
     return not page.page_set.pages.index(page)
 
@@ -31,15 +41,26 @@ class TabSwitching(page_measurement.PageMeasurement):
     for i in xrange(1, len(page.page_set.pages)):
       t = tab.browser.tabs.New()
 
+      # We create a test_stub to be able to call 'navigate_steps' on pages
+      test_stub = page_measurement.PageMeasurement()
       page_state = page_runner.PageState()
       page_state.PreparePage(page.page_set.pages[i], t)
-      page_state.ImplicitPageNavigation(page.page_set.pages[i], t)
+      page_state.ImplicitPageNavigation(page.page_set.pages[i], t, test_stub)
 
-  def MeasurePage(self, _, tab, results):
+    # Start tracking cpu load after all pages have loaded.
+    self._cpu_metric.Start(page, tab)
+
+  def MeasurePage(self, page, tab, results):
     """Although this is called MeasurePage, we're actually using this function
     to cycle through each tab that was opened via DidNavigateToPage and
     then record a single histogram for the tab switching metric.
     """
+    # Calculate the idle cpu load before any actions are done.
+    time.sleep(.5)
+    self._cpu_metric.Stop(page, tab)
+    self._cpu_metric.AddResults(tab, results,
+                                'idle_cpu_utilization')
+
     histogram_name = 'MPArch.RWH_TabSwitchPaintDuration'
     histogram_type = histogram_util.BROWSER_HISTOGRAM
     first_histogram = histogram_util.GetHistogramFromDomAutomation(
diff --git a/tools/perf/metrics/cpu.py b/tools/perf/metrics/cpu.py
new file mode 100644
index 0000000..18a9c80
--- /dev/null
+++ b/tools/perf/metrics/cpu.py
@@ -0,0 +1,55 @@
+# 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.
+
+from metrics import Metric
+
+class Cpu(Metric):
+  """Calulates CPU load over a span of time."""
+
+  def __init__(self, browser):
+    super(Cpu, self).__init__()
+    self._results = None
+    self._browser = browser
+    self.start_cpu = None
+
+  def DidStartBrowser(self, browser):
+    # Save the browser for cpu_stats.
+    self._browser = browser
+
+  def Start(self, page, tab):
+    self.start_cpu = self._browser.cpu_stats
+
+  def Stop(self, page, tab):
+    assert self.start_cpu != None, 'Must call Start() first'
+    self._results = Cpu.SubtractCpuStats(self._browser.cpu_stats,
+                                         self.start_cpu)
+
+  # pylint: disable=W0221
+  def AddResults(self, tab, results, trace_name='cpu_utilization'):
+    assert self._results != None, 'Must call Stop() first'
+    for process_type in self._results:
+      results.Add(trace_name + '_%s' % process_type.lower(),
+                  '%',
+                  self._results[process_type]['CpuPercent'],
+                  chart_name='cpu_utilization',
+                  data_type='unimportant')
+
+  @staticmethod
+  def SubtractCpuStats(cpu_stats, start_cpu_stats):
+    """Returns difference of a previous cpu_stats from a cpu_stats."""
+    diff = {}
+    for process_type in cpu_stats:
+      assert process_type in start_cpu_stats, 'Mismatching process types'
+      # Skip any process_types that are empty.
+      if (not len(cpu_stats[process_type]) or
+          not len(start_cpu_stats[process_type])):
+        continue
+      cpu_process_time = (cpu_stats[process_type]['CpuProcessTime'] -
+                          start_cpu_stats[process_type]['CpuProcessTime'])
+      total_time = (cpu_stats[process_type]['TotalTime'] -
+                    start_cpu_stats[process_type]['TotalTime'])
+      assert total_time > 0
+      cpu_percent = 100 * cpu_process_time / total_time
+      diff[process_type] = {'CpuPercent': cpu_percent}
+    return diff