telemetry: Improve perf profiler

tools/telemetry/telemetry/core/platform/profiler/perf_profiler.py

Index: tools/telemetry/telemetry/core/platform/profiler/perf_profiler.py
diff --git a/tools/telemetry/telemetry/core/platform/profiler/perf_profiler.py b/tools/telemetry/telemetry/core/platform/profiler/perf_profiler.py
index 4e0c9eae9f6bebe0731fb161f257c813be7b0921..f32eba30f7bd91b53618d5530afe6910b6b90786 100644
--- a/tools/telemetry/telemetry/core/platform/profiler/perf_profiler.py
+++ b/tools/telemetry/telemetry/core/platform/profiler/perf_profiler.py
@@ -10,9 +10,52 @@ import subprocess
 import sys
 import tempfile
 
+from telemetry.core import platform
 from telemetry.core import util
 from telemetry.core.platform import profiler
 from telemetry.core.platform.profiler import android_profiling_helper
+from telemetry.util import support_binaries
+
+util.AddDirToPythonPath(util.GetChromiumSrcDir(), 'build', 'android')
+from pylib.perf import perf_control  # pylint: disable=F0401
+
+
+_PERF_OPTIONS = [
+    # In perf 3.13 --call-graph requires an argument, so use the -g short-hand
+    # which does not.
+    '-g',
+    # Increase sampling frequency for better coverage.
+    '--freq', '2000',
+]
+
+_PERF_OPTIONS_ANDROID = [
+    # Increase priority to avoid dropping samples. Requires root.
+    '--realtime', '80',
+]
+
+
+def _NicePath(path):
+  rel_path = os.path.relpath(path, os.curdir)
+  return rel_path if len(rel_path) < len(path) else path
+
+
+def _PrepareHostForPerf():
+  kptr_file = '/proc/sys/kernel/kptr_restrict'
+  with open(kptr_file) as f:
+    if f.read().strip() != '0':
+      logging.warning('Making kernel symbols unrestricted. You might have to '
+          'enter your password for "sudo".')
+      with tempfile.NamedTemporaryFile() as zero:
+        zero.write('0')
+        zero.flush()
+        subprocess.call(['sudo', 'cp', zero.name, kptr_file])
+
+
+def _InstallPerfHost():
+  host = platform.GetHostPlatform()
+  if not host.CanLaunchApplication('perfhost'):
+    host.InstallApplication('perfhost')
+  return support_binaries.FindPath('perfhost', host.GetOSName())
 
 
 class _SingleProcessPerfProfiler(object):
@@ -22,17 +65,20 @@ class _SingleProcessPerfProfiler(object):
   See more details in prebuilt/android/README.txt.
   """
   def __init__(self, pid, output_file, browser_backend, platform_backend,
-               perf_binary):
+               perf_binary, perfhost_binary):
     self._pid = pid
     self._browser_backend = browser_backend
     self._platform_backend = platform_backend
     self._output_file = output_file
     self._tmp_output_file = tempfile.NamedTemporaryFile('w', 0)
     self._is_android = platform_backend.GetOSName() == 'android'
+    self._perfhost_binary = perfhost_binary
     cmd_prefix = []
+    perf_args = ['record', '--pid', str(pid)]
     if self._is_android:
       cmd_prefix = ['adb', '-s', browser_backend.adb.device_serial(), 'shell',
                     perf_binary]
+      perf_args += _PERF_OPTIONS_ANDROID
       output_file = os.path.join('/sdcard', 'perf_profiles',
                                  os.path.basename(output_file))
       self._device_output_file = output_file
@@ -41,11 +87,8 @@ class _SingleProcessPerfProfiler(object):
       browser_backend.adb.RunShellCommand('rm -f ' + self._device_output_file)
     else:
       cmd_prefix = [perf_binary]
-    # In perf 3.13 --call-graph requires an argument, so use
-    # the -g short-hand which does not.
-    self._proc = subprocess.Popen(cmd_prefix +
-        ['record', '-g',
-         '--pid', str(pid), '--output', output_file],
+    perf_args += ['--output', output_file] + _PERF_OPTIONS
+    self._proc = subprocess.Popen(cmd_prefix + perf_args,
         stdout=self._tmp_output_file, stderr=subprocess.STDOUT)
 
   def CollectProfile(self):
@@ -77,7 +120,8 @@ Try rerunning this script under sudo or setting
                                                             self._GetStdOut()))
     finally:
       self._tmp_output_file.close()
-    cmd = 'perf report -n -i %s' % self._output_file
+    cmd = '%s report -n -i %s' % (_NicePath(self._perfhost_binary),
+                                  self._output_file)
     if self._is_android:
       device = self._browser_backend.adb.device()
       device.old_interface.Adb().Pull(self._device_output_file,
@@ -91,13 +135,15 @@ Try rerunning this script under sudo or setting
                                                       required_libs,
                                                       use_symlinks=True)
       cmd += ' --symfs %s --kallsyms %s' % (symfs_root, kallsyms)
-
-      objdump_path = os.path.join(os.environ.get('ANDROID_TOOLCHAIN',
-                                                 '$ANDROID_TOOLCHAIN'),
-                                  'arm-linux-androideabi-objdump')
-      print 'If you have recent version of perf (3.10+), append the following '
-      print 'to see annotated source code (by pressing the \'a\' key): '
-      print '  --objdump %s' % objdump_path
+      for lib in required_libs:
+        lib = os.path.join(symfs_root, lib[1:])
+        if not os.path.exists(lib):
+          continue
+        objdump_path = android_profiling_helper.GetToolchainBinaryPath(
+            lib, 'objdump')
+        if objdump_path:
+          cmd += ' --objdump %s' % _NicePath(objdump_path)
+          break
 
     print 'To view the profile, run:'
     print ' ', cmd
@@ -119,17 +165,29 @@ class PerfProfiler(profiler.Profiler):
         browser_backend, platform_backend, output_path, state)
     process_output_file_map = self._GetProcessOutputFileMap()
     self._process_profilers = []
-    perf_binary = 'perf'
-    if platform_backend.GetOSName() == 'android':
-      perf_binary = android_profiling_helper.PrepareDeviceForPerf(
-          browser_backend.adb.device())
+    self._is_android = platform_backend.GetOSName() == 'android'
 
-    for pid, output_file in process_output_file_map.iteritems():
-      if 'zygote' in output_file:
-        continue
-      self._process_profilers.append(
-          _SingleProcessPerfProfiler(
-              pid, output_file, browser_backend, platform_backend, perf_binary))
+    perf_binary = perfhost_binary = _InstallPerfHost()
+    try:
+      if self._is_android:
+        device = browser_backend.adb.device()
+        perf_binary = android_profiling_helper.PrepareDeviceForPerf(device)
+        self._perf_control = perf_control.PerfControl(device)
+        self._perf_control.ForceAllCpusOnline(True)
+      else:
+        _PrepareHostForPerf()
+
+      for pid, output_file in process_output_file_map.iteritems():
+        if 'zygote' in output_file:
+          continue
+        self._process_profilers.append(
+            _SingleProcessPerfProfiler(
+                pid, output_file, browser_backend, platform_backend,
+                perf_binary, perfhost_binary))
+    except:
+      if self._is_android:
+        self._perf_control.ForceAllCpusOnline(False)
+      raise
 
   @classmethod
   def name(cls):
@@ -141,17 +199,7 @@ class PerfProfiler(profiler.Profiler):
       return False
     if browser_type.startswith('cros'):
       return False
-    return cls._CheckLinuxPerf() or browser_type.startswith('android')
-
-  @classmethod
-  def _CheckLinuxPerf(cls):
-    try:
-      with open(os.devnull, 'w') as devnull:
-        return not subprocess.Popen(['perf', '--version'],
-                                    stderr=devnull,
-                                    stdout=devnull).wait()
-    except OSError:
-      return False
+    return True
 
   @classmethod
   def CustomizeBrowserOptions(cls, browser_type, options):
@@ -161,6 +209,8 @@ class PerfProfiler(profiler.Profiler):
     ])
 
   def CollectProfile(self):
+    if self._is_android:
+      self._perf_control.ForceAllCpusOnline(False)
     output_files = []
     for single_process in self._process_profilers:
       output_files.append(single_process.CollectProfile())
@@ -173,8 +223,9 @@ class PerfProfiler(profiler.Profiler):
     """
     assert os.path.exists(file_name)
     with open(os.devnull, 'w') as devnull:
+      _InstallPerfHost()
       report = subprocess.Popen(
-          ['perf', 'report', '--show-total-period', '-U', '-t', '^', '-i',
+          ['perfhost', 'report', '--show-total-period', '-U', '-t', '^', '-i',
            file_name],
           stdout=subprocess.PIPE, stderr=devnull).communicate()[0]
     period_by_function = {}