Tab Switching Benchmark for ChromeOS

tools/perf/contrib/cros_benchmarks/cros_utils.py

+# Copyright 2017 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 json
+import logging
+import os
+import subprocess
+
+import py_utils
+
+from telemetry.core import exceptions
+from telemetry.value import histogram_util
+
+
+def _RunRemoteCommand(dut_ip, cmd):
+  return os.system('ssh root@%s %s' % (dut_ip, cmd))
+
+
+def _GetTabSwitchHistogram(browser):
+  """Gets MPArch.RWH_TabSwitchPaintDuration histogram.
+
+  Catches exceptions to handle devtools context lost cases.
+
+  Any tab context can be used to get the TabSwitchPaintDuration histogram.
+  browser.tabs[-1] is the last valid context. Ex: If the browser opens
+  A, B, ..., I, J tabs, E, F, G tabs have valid contexts (not discarded),
+  then browser.tab[0] is tab E, browser.tab[-1] is tab G.
+
+  In the tab switching benchmark, the tabs are opened and switched to in
+  1, 2, ..., n order. The tabs are discarded in roughly 1, 2, ..., n order
+  (LRU order). The changce of discarding the last valid context is lower
+  than discarding the first valid context.

[cylee1, 2017/05/25 21:21:35]

chance

[vovoy, 2017/05/26 08:19:35]

Done.

+
+  Args:
+    browser: Gets histogram from this browser.
+
+  Returns:
+    A json serialization of a histogram or None if get histogram failed.
+  """
+  histogram_name = 'MPArch.RWH_TabSwitchPaintDuration'
+  histogram_type = histogram_util.BROWSER_HISTOGRAM
+  try:
+    return histogram_util.GetHistogram(
+        histogram_type, histogram_name, browser.tabs[-1])
+  except exceptions.DevtoolsTargetCrashException:

[cylee1, 2017/05/25 21:21:35]

Does except (exception1, exception2) work to merge the two exceptions?

[vovoy, 2017/05/26 08:19:35]

Done.

+    logging.info('GetHistogram: devtools context lost')
+  except KeyError:
+    logging.info('GetHistogram: devtools context lost')
+  except Exception as e:
+    logging.warning('GetHistogram: exception')
+    logging.warning(e)
+  return None
+
+
+def GetTabSwitchHistogramRetry(browser):
+  """Retries getting histogram as it may fail when a context was discarded.
+
+  Args:
+    browser: Gets histogram from this browser.
+
+  Returns:
+    A json serialization of a histogram.
+  Raises:
+    py_utils.TimeoutException: There is no valid histogram in 10 seconds.
+  """
+  def _TryGetHistogram():
+    return _GetTabSwitchHistogram(browser)
+  return py_utils.WaitFor(_TryGetHistogram, 10)

[cylee1, 2017/05/25 21:21:34]

Could _TryGetHistogram be replaced by
  lambda: _GetTabSwitchHistogram(browser) 
?

[vovoy, 2017/05/26 08:19:35]

Done.

+
+
+def WaitTabSwitching(browser, prev_histogram):
+  """Waits for tab switching completion.
+
+  It's done by checking browser histogram to see if
+  RWH_TabSwitchPaintDuration count increases.
+
+  Args:
+    browser: Gets histogram from this browser.
+    prev_histogram: Checks histogram change against this histogram.
+  """
+  def _IsDone():
+    cur_histogram = _GetTabSwitchHistogram(browser)
+    if not cur_histogram:
+      return False
+
+    diff_histogram = histogram_util.SubtractHistogram(
+        cur_histogram, prev_histogram)
+    diff_histogram_count = json.loads(diff_histogram).get('count', 0)
+    return diff_histogram_count > 0
+
+  try:
+    py_utils.WaitFor(_IsDone, 10)
+  except py_utils.TimeoutException:
+    logging.warning('Timed out waiting for histogram count increasing.')
+
+
+class KeyboardEmulator(object):
+  """Sets up a remote emulated keyboard and sends key events to switch tab.
+
+  Example usage:
+    with KeyboardEmulator(DUT_IP) as kbd:
+      for i in range(5):
+        kbd.SwitchTab()
+  """
+
+  def __init__(self, dut_ip):
+    """Inits KeyboardEmulator.
+
+    Args:
+      dut_ip: DUT IP or hostname.
+    """
+    self._dut_ip = dut_ip
+    self._root_dut_ip = 'root@' + dut_ip
+
+  def _StartRemoteKeyboardEmulator(self):
+    """Starts keyboard emulator on the DUT.
+
+    Returns:
+      The device name of the emulated keyboard.
+
+    Raises:
+      RuntimeError: Keyboard emulation failed.
+    """
+    kbd_prop_filename = '/usr/local/autotest/cros/input_playback/keyboard.prop'
+
+    ret = _RunRemoteCommand(self._dut_ip, 'test -e %s' % kbd_prop_filename)
+    if ret != 0:
+      raise RuntimeError('Keyboard property file does not exist.')
+
+    cmd = ['ssh', self._root_dut_ip, 'evemu-device', kbd_prop_filename]
+    ssh_process = subprocess.Popen(cmd, stdout=subprocess.PIPE)
+
+    # The evemu-device output format:
+    # Emulated Keyboard: /dev/input/event10
+    output = ssh_process.stdout.readline()
+    if not output.startswith('Emulated Keyboard:'):
+      raise RuntimeError('Keyboard emulation failed.')

[cylee1, 2017/05/25 21:21:35]

ssh_process.kill() wouldn't be executed if an error is thrown here?

[vovoy, 2017/05/26 08:19:35]

Fixed. Kills before throwing exception.

+    key_device_name = output.split()[2]
+
+    # The remote process would live when the ssh process was terminated.
+    ssh_process.kill()
+
+    return key_device_name
+
+  def _SetupKeyDispatch(self, device_name):
+    """Uploads the script to send key to switch tabs."""
+    cur_dir = os.path.dirname(os.path.abspath(__file__))
+    send_key_filename = os.path.join(cur_dir, 'data', 'send_key_tab_switch')
+    log_key_filename = os.path.join(cur_dir, 'data', 'log_key_tab_switch')
+
+    with open(send_key_filename, 'w') as f:
+      remote_log_key_filename = '/usr/local/tmp/log_key_tab_switch'
+      f.write('#!/bin/bash\n')

[cylee1, 2017/05/25 21:21:34]

could you put the whole file content in a string for better readability ?

[vovoy, 2017/05/26 08:19:35]

Rewritten. Runs the command directly instead of uploading a script file.

+      f.write('evemu-play --insert-slot0 %s < %s' %
+              (device_name, remote_log_key_filename))
+    os.chmod(send_key_filename, 0774)
+
+    os.system('scp -q %s %s:/usr/local/tmp/' %
+              (log_key_filename, self._root_dut_ip))
+    os.system('scp -q %s %s:/usr/local/tmp/' %
+              (send_key_filename, self._root_dut_ip))
+
+  def __enter__(self):
+    key_device_name = self._StartRemoteKeyboardEmulator()
+    self._SetupKeyDispatch(key_device_name)
+    return self
+
+  def SwitchTab(self):
+    """Sending Ctrl-tab key to trigger tab switching."""
+    _RunRemoteCommand(self._dut_ip, '/usr/local/tmp/send_key_tab_switch')
+
+  def __exit__(self, exc_type, exc_value, traceback):
+    # Kills the remote emulator process explicitly.
+    _RunRemoteCommand(self._dut_ip, 'pkill evemu-device')
+
+
+def NoScreenOff(dut_ip):
+  """Sets screen always on for 1 hour.
+
+  Args:
+    dut_ip: DUT IP or hostname.
+  """
+  _RunRemoteCommand(dut_ip, 'set_power_policy --ac_screen_off_delay=3600')
+  _RunRemoteCommand(dut_ip, 'set_power_policy --ac_screen_dim_delay=3600')