Purge unpinned ashmem before parsing /proc/$pid/smaps.

build/android/pylib/android_commands.py

Index: build/android/pylib/android_commands.py
diff --git a/build/android/pylib/android_commands.py b/build/android/pylib/android_commands.py
index 1741619276ce56042a9a3df6f3b004fed1ebe3ad..739d9be3efe40a555f326db26a78c3e5662082b4 100644
--- a/build/android/pylib/android_commands.py
+++ b/build/android/pylib/android_commands.py
@@ -1409,6 +1409,59 @@ class AndroidCommands(object):
     logging.warning('Could not find disk IO stats.')
     return None
 
+  @staticmethod
+  def _GetExistingHostOutputPath(file_name):

[frankf, 2013/11/04 18:17:06]

If you decide to keep this, it should be moved to a utility module in
pylib/utils since it's not related to adb commands.

+    """Returns the most likely correct full path for the given file name.
+
+    Returns: The full path that was found or throws an exception if no path
+             could be found.
+    """
+    candidate_path = None
+    build_type = None
+    out_dir = os.path.join(
+        constants.DIR_SOURCE_ROOT, os.environ.get('CHROMIUM_OUT_DIR', 'out'))
+
+    if constants.BuildTypeIsSet():

[Philippe, 2013/10/30 17:18:21]

FYI, this condition is not always met which is why I wrote this function rather
than directly using constants.GetOutDirectory(). I'm making this function
private for now but I expect that other clients could make it public and use it
later.

[craigdh, 2013/10/31 00:10:13]

My understanding is that the goal is to support arbitrary out/* directories,
which is why all assumptions of Debug/Release were removed. To support an
arbitrary build type it must be passed in and set somewhere as there is no
reliable way to pick the right out directory. I'm opposed to magic searching for
common cases, explicit is better.

[Philippe, 2013/11/04 14:45:55]

I will let Marcus comment on this :)

+      candidate_path = os.path.join(
+          out_dir, constants.GetBuildType(), file_name)
+    else:
+      release_path = os.path.join(out_dir, 'Release', file_name)
+      debug_path = os.path.join(out_dir, 'Debug', file_name)
+
+      if os.path.exists(release_path):
+        if os.path.exists(debug_path):
+          # Retain the most recent file.
+          release_path_mtime = time.ctime(os.path.getmtime(release_path))
+          debug_path_mtime = time.ctime(os.path.getmtime(debug_path))
+          if release_path_mtime > debug_path_mtime:
+            constants.SetBuildType('Release')
+            return release_path
+          constants.SetBuildType('Debug')
+          return debug_path
+        candidate_path = release_path
+        build_type = 'Release'
+      else:
+        candidate_path = debug_path
+        build_type = 'Debug'

[digit1, 2013/11/04 14:15:55]

I'm ok with self-detection, but if you don't plan to remove this, please ensure
that there is a logging.warning() call here to notify the user. This will help
catch surprises later on.

[Philippe, 2013/11/04 14:45:55]

Yeah good idea. We got bitten more than once with this :)

+
+    if not os.path.exists(candidate_path):
+      raise Exception('File %s does not exist' % candidate_path)
+
+    if build_type:
+      constants.SetBuildType(build_type)
+    return candidate_path
+
+  def _PurgeUnpinnedAshmem(self):
+    """Purges the unpinned ashmem memory for the whole system.
+
+    This can be used to make memory measurements more stable in particular.
+    """
+    host_path = AndroidCommands._GetExistingHostOutputPath('purge_ashmem')
+    device_path = os.path.join(constants.TEST_EXECUTABLE_DIR, 'purge_ashmem')
+    self.PushIfNeeded(host_path, device_path)
+    if not self.RunShellCommand(device_path, log_result=True):
+      logging.warning('Could not purge ashmem. Measurement might be unstable.')
+
   def GetMemoryUsageForPid(self, pid):
     """Returns the memory usage for given pid.
 
@@ -1425,6 +1478,7 @@ class AndroidCommands(object):
     """
     usage_dict = collections.defaultdict(int)
     smaps = collections.defaultdict(dict)
+    self._PurgeUnpinnedAshmem()

[tonyg, 2013/11/03 05:05:18]

Telemetry calls GetMemoryUsageForPid, and before we introduce this dependency on
a new binary, we need to check it into cloud storage like the other binaries
required to run on android. We don't want to require building anything in order
to run Telemetry on Android.

See: SetupPrebuiltTools in adb_commands.py

We also need to update instructions on the Telemetry wiki and error messages.

[Philippe, 2013/11/04 14:45:55]

Thanks for the instructions Tony. I have just pushed the 'purge_ashmem' ARM
release binary to cloud storage (since it looked good to David). I added the
corresponding SHA1 file and updated SetupPrebuildTools(). I haven't seen any
specific documentation that I should update?

     current_smap = ''
     for line in self.GetProtectedFileContents('/proc/%s/smaps' % pid,
                                               log_result=False):