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1# Copyright 2013 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
6import logging
7
8
9class PerfControl(object):
10  """Provides methods for setting the performance mode of a device."""
11  _SCALING_GOVERNOR_FMT = (
12      '/sys/devices/system/cpu/cpu%d/cpufreq/scaling_governor')
13  _KERNEL_MAX = '/sys/devices/system/cpu/kernel_max'
14
15  def __init__(self, adb):
16    self._adb = adb
17    kernel_max = self._adb.GetFileContents(PerfControl._KERNEL_MAX,
18                                           log_result=False)
19    assert kernel_max, 'Unable to find %s' % PerfControl._KERNEL_MAX
20    self._kernel_max = int(kernel_max[0])
21    logging.info('Maximum CPU index: %d', self._kernel_max)
22    self._original_scaling_governor = self._adb.GetFileContents(
23        PerfControl._SCALING_GOVERNOR_FMT % 0,
24        log_result=False)[0]
25
26  def SetHighPerfMode(self):
27    """Sets the highest possible performance mode for the device."""
28    self._SetScalingGovernorInternal('performance')
29
30  def SetDefaultPerfMode(self):
31    """Sets the performance mode for the device to its default mode."""
32    product_model = self._adb.GetProductModel()
33    governor_mode = {
34        'GT-I9300': 'pegasusq',
35        'Galaxy Nexus': 'interactive',
36        'Nexus 4': 'ondemand',
37        'Nexus 7': 'interactive',
38        'Nexus 10': 'interactive'
39    }.get(product_model, 'ondemand')
40    self._SetScalingGovernorInternal(governor_mode)
41
42  def RestoreOriginalPerfMode(self):
43    """Resets the original performance mode of the device."""
44    self._SetScalingGovernorInternal(self._original_scaling_governor)
45
46  def _SetScalingGovernorInternal(self, value):
47    for cpu in range(self._kernel_max + 1):
48      scaling_governor_file = PerfControl._SCALING_GOVERNOR_FMT % cpu
49      if self._adb.FileExistsOnDevice(scaling_governor_file):
50        logging.info('Writing scaling governor mode \'%s\' -> %s',
51                     value, scaling_governor_file)
52        self._adb.SetProtectedFileContents(scaling_governor_file, value)
53