Add a snapshot of flutter/engine/src/build to our sdk

build/android/pylib/perf/perf_control.py

Index: build/android/pylib/perf/perf_control.py
diff --git a/build/android/pylib/perf/perf_control.py b/build/android/pylib/perf/perf_control.py
new file mode 100644
index 0000000000000000000000000000000000000000..f89f397d24e2930f54a8d737aeb54166912555e4
--- /dev/null
+++ b/build/android/pylib/perf/perf_control.py
@@ -0,0 +1,161 @@
+# 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.
+
+import atexit
+import logging
+
+from pylib import android_commands
+from pylib.device import device_errors
+from pylib.device import device_utils
+
+
+class PerfControl(object):
+  """Provides methods for setting the performance mode of a device."""
+  _CPU_PATH = '/sys/devices/system/cpu'
+  _KERNEL_MAX = '/sys/devices/system/cpu/kernel_max'
+
+  def __init__(self, device):
+    # TODO(jbudorick) Remove once telemetry gets switched over.
+    if isinstance(device, android_commands.AndroidCommands):
+      device = device_utils.DeviceUtils(device)
+    self._device = device
+    # this will raise an AdbCommandFailedError if no CPU files are found
+    self._cpu_files = self._device.RunShellCommand(
+        'ls -d cpu[0-9]*', cwd=self._CPU_PATH, check_return=True, as_root=True)
+    assert self._cpu_files, 'Failed to detect CPUs.'
+    self._cpu_file_list = ' '.join(self._cpu_files)
+    logging.info('CPUs found: %s', self._cpu_file_list)
+    self._have_mpdecision = self._device.FileExists('/system/bin/mpdecision')
+
+  def SetHighPerfMode(self):
+    """Sets the highest stable performance mode for the device."""
+    try:
+      self._device.EnableRoot()
+    except device_errors.CommandFailedError:
+      message = 'Need root for performance mode. Results may be NOISY!!'
+      logging.warning(message)
+      # Add an additional warning at exit, such that it's clear that any results
+      # may be different/noisy (due to the lack of intended performance mode).
+      atexit.register(logging.warning, message)
+      return
+
+    product_model = self._device.product_model
+    # TODO(epenner): Enable on all devices (http://crbug.com/383566)
+    if 'Nexus 4' == product_model:
+      self._ForceAllCpusOnline(True)
+      if not self._AllCpusAreOnline():
+        logging.warning('Failed to force CPUs online. Results may be NOISY!')
+      self._SetScalingGovernorInternal('performance')
+    elif 'Nexus 5' == product_model:
+      self._ForceAllCpusOnline(True)
+      if not self._AllCpusAreOnline():
+        logging.warning('Failed to force CPUs online. Results may be NOISY!')
+      self._SetScalingGovernorInternal('performance')
+      self._SetScalingMaxFreq(1190400)
+      self._SetMaxGpuClock(200000000)
+    else:
+      self._SetScalingGovernorInternal('performance')
+
+  def SetPerfProfilingMode(self):
+    """Enables all cores for reliable perf profiling."""
+    self._ForceAllCpusOnline(True)
+    self._SetScalingGovernorInternal('performance')
+    if not self._AllCpusAreOnline():
+      if not self._device.HasRoot():
+        raise RuntimeError('Need root to force CPUs online.')
+      raise RuntimeError('Failed to force CPUs online.')
+
+  def SetDefaultPerfMode(self):
+    """Sets the performance mode for the device to its default mode."""
+    if not self._device.HasRoot():
+      return
+    product_model = self._device.product_model
+    if 'Nexus 5' == product_model:
+      if self._AllCpusAreOnline():
+        self._SetScalingMaxFreq(2265600)
+        self._SetMaxGpuClock(450000000)
+
+    governor_mode = {
+        'GT-I9300': 'pegasusq',
+        'Galaxy Nexus': 'interactive',
+        'Nexus 4': 'ondemand',
+        'Nexus 5': 'ondemand',
+        'Nexus 7': 'interactive',
+        'Nexus 10': 'interactive'
+    }.get(product_model, 'ondemand')
+    self._SetScalingGovernorInternal(governor_mode)
+    self._ForceAllCpusOnline(False)
+
+  def GetCpuInfo(self):
+    online = (output.rstrip() == '1' and status == 0
+              for (_, output, status) in self._ForEachCpu('cat "$CPU/online"'))
+    governor = (output.rstrip() if status == 0 else None
+                for (_, output, status)
+                in self._ForEachCpu('cat "$CPU/cpufreq/scaling_governor"'))
+    return zip(self._cpu_files, online, governor)
+
+  def _ForEachCpu(self, cmd):
+    script = '; '.join([
+        'for CPU in %s' % self._cpu_file_list,
+        'do %s' % cmd,
+        'echo -n "%~%$?%~%"',
+        'done'
+    ])
+    output = self._device.RunShellCommand(
+        script, cwd=self._CPU_PATH, check_return=True, as_root=True)
+    output = '\n'.join(output).split('%~%')
+    return zip(self._cpu_files, output[0::2], (int(c) for c in output[1::2]))
+
+  def _WriteEachCpuFile(self, path, value):
+    results = self._ForEachCpu(
+        'test -e "$CPU/{path}" && echo {value} > "$CPU/{path}"'.format(
+            path=path, value=value))
+    cpus = ' '.join(cpu for (cpu, _, status) in results if status == 0)
+    if cpus:
+      logging.info('Successfully set %s to %r on: %s', path, value, cpus)
+    else:
+      logging.warning('Failed to set %s to %r on any cpus')
+
+  def _SetScalingGovernorInternal(self, value):
+    self._WriteEachCpuFile('cpufreq/scaling_governor', value)
+
+  def _SetScalingMaxFreq(self, value):
+    self._WriteEachCpuFile('cpufreq/scaling_max_freq', '%d' % value)
+
+  def _SetMaxGpuClock(self, value):
+    self._device.WriteFile('/sys/class/kgsl/kgsl-3d0/max_gpuclk',
+                           str(value),
+                           as_root=True)
+
+  def _AllCpusAreOnline(self):
+    results = self._ForEachCpu('cat "$CPU/online"')
+    # TODO(epenner): Investigate why file may be missing
+    # (http://crbug.com/397118)
+    return all(output.rstrip() == '1' and status == 0
+               for (cpu, output, status) in results
+               if cpu != 'cpu0')
+
+  def _ForceAllCpusOnline(self, force_online):
+    """Enable all CPUs on a device.
+
+    Some vendors (or only Qualcomm?) hot-plug their CPUs, which can add noise
+    to measurements:
+    - In perf, samples are only taken for the CPUs that are online when the
+      measurement is started.
+    - The scaling governor can't be set for an offline CPU and frequency scaling
+      on newly enabled CPUs adds noise to both perf and tracing measurements.
+
+    It appears Qualcomm is the only vendor that hot-plugs CPUs, and on Qualcomm
+    this is done by "mpdecision".
+
+    """
+    if self._have_mpdecision:
+      script = 'stop mpdecision' if force_online else 'start mpdecision'
+      self._device.RunShellCommand(script, check_return=True, as_root=True)
+
+    if not self._have_mpdecision and not self._AllCpusAreOnline():
+      logging.warning('Unexpected cpu hot plugging detected.')
+
+    if force_online:
+      self._ForEachCpu('echo 1 > "$CPU/online"')