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      1 # Copyright 2014 The Chromium Authors. All rights reserved.
      2 # Use of this source code is governed by a BSD-style license that can be
      3 # found in the LICENSE file.
      4 
      5 from metrics import Metric
      6 from telemetry.value import scalar
      7 
      8 class PowerMetric(Metric):
      9   """A metric for measuring power usage."""
     10 
     11   def __init__(self):
     12     super(PowerMetric, self).__init__()
     13     self._browser = None
     14     self._running = False
     15     self._starting_cpu_stats = None
     16     self._results = None
     17 
     18   def __del__(self):
     19     # TODO(jeremy): Remove once crbug.com/350841 is fixed.
     20     # Don't leave power monitoring processes running on the system.
     21     self._StopInternal()
     22     parent = super(PowerMetric, self)
     23     if hasattr(parent, '__del__'):
     24       parent.__del__()
     25 
     26   def _StopInternal(self):
     27     """ Stop monitoring power if measurement is running. This function is
     28     idempotent."""
     29     if not self._running:
     30       return
     31     self._running = False
     32     self._results = self._browser.platform.StopMonitoringPower()
     33     if self._results: # StopMonitoringPower() can return None.
     34       self._results['cpu_stats'] = (
     35           _SubtractCpuStats(self._browser.cpu_stats, self._starting_cpu_stats))
     36 
     37   def Start(self, _, tab):
     38     if not tab.browser.platform.CanMonitorPower():
     39       return
     40 
     41     self._results = None
     42     self._browser = tab.browser
     43     self._StopInternal()
     44 
     45     # This line invokes top a few times, call before starting power measurement.
     46     self._starting_cpu_stats = self._browser.cpu_stats
     47     self._browser.platform.StartMonitoringPower(self._browser)
     48     self._running = True
     49 
     50   def Stop(self, _, tab):
     51     if not tab.browser.platform.CanMonitorPower():
     52       return
     53 
     54     self._StopInternal()
     55 
     56   def AddResults(self, _, results):
     57     """Add the collected power data into the results object.
     58 
     59     This function needs to be robust in the face of differing power data on
     60     various platforms. Therefore data existence needs to be checked when
     61     building up the results. Additionally 0 is a valid value for many of the
     62     metrics here which is why there are plenty of checks for 'is not None'
     63     below.
     64     """
     65     if not self._results:
     66       return
     67 
     68     energy_consumption_mwh = self._results.get('energy_consumption_mwh')
     69     if energy_consumption_mwh is not None:
     70       results.AddValue(scalar.ScalarValue(
     71           results.current_page, 'energy_consumption_mwh', 'mWh',
     72           energy_consumption_mwh))
     73 
     74     component_utilization = self._results.get('component_utilization', {})
     75     # GPU Frequency.
     76     gpu_power = component_utilization.get('gpu', {})
     77     gpu_freq_hz = gpu_power.get('average_frequency_hz')
     78     if gpu_freq_hz is not None:
     79       results.AddValue(scalar.ScalarValue(
     80           results.current_page, 'gpu_average_frequency_hz', 'hz', gpu_freq_hz,
     81           important=False))
     82 
     83     # Add idle wakeup numbers for all processes.
     84     for (process_type, stats) in self._results.get('cpu_stats', {}).items():
     85       trace_name_for_process = 'idle_wakeups_%s' % (process_type.lower())
     86       results.AddValue(scalar.ScalarValue(
     87           results.current_page, trace_name_for_process, 'count', stats,
     88           important=False))
     89 
     90     # Add temperature measurements.
     91     whole_package_utilization = component_utilization.get('whole_package', {})
     92     board_temperature_c = whole_package_utilization.get('average_temperature_c')
     93     if board_temperature_c is not None:
     94       results.AddValue(scalar.ScalarValue(
     95           results.current_page, 'board_temperature', 'celsius',
     96           board_temperature_c, important=False))
     97 
     98     self._results = None
     99 
    100 def _SubtractCpuStats(cpu_stats, start_cpu_stats):
    101   """Computes number of idle wakeups that occurred over measurement period.
    102 
    103   Each of the two cpu_stats arguments is a dict as returned by the
    104   Browser.cpu_stats call.
    105 
    106   Returns:
    107     A dict of process type names (Browser, Renderer, etc.) to idle wakeup count
    108     over the period recorded by the input.
    109   """
    110   cpu_delta = {}
    111   for process_type in cpu_stats:
    112     assert process_type in start_cpu_stats, 'Mismatching process types'
    113     # Skip any process_types that are empty.
    114     if (not cpu_stats[process_type]) or (not start_cpu_stats[process_type]):
    115       continue
    116     # Skip if IdleWakeupCount is not present.
    117     if (('IdleWakeupCount' not in cpu_stats[process_type]) or
    118         ('IdleWakeupCount' not in start_cpu_stats[process_type])):
    119       continue
    120     idle_wakeup_delta = (cpu_stats[process_type]['IdleWakeupCount'] -
    121                         start_cpu_stats[process_type]['IdleWakeupCount'])
    122     cpu_delta[process_type] = idle_wakeup_delta
    123   return cpu_delta
    124