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..a155ee105d3c628f6e7319df78f452097e3489ad 100644
--- a/build/android/pylib/android_commands.py
+++ b/build/android/pylib/android_commands.py
@@ -1409,6 +1409,60 @@ class AndroidCommands(object):
     logging.warning('Could not find disk IO stats.')
     return None
 
+  @staticmethod
+  def _GetExistingHostOutputPath(file_name):

[bulach, 2013/11/04 20:22:06]

perhaps we should make the following a public API?

https://codereview.chromium.org/55923003/diff/1/third_party/android_platform/...

see TranslateLibPath, it essentially gets all possible file names, then filters
with os.path.exists and sorts with os.path.getmtime.. I think cjhopman wrote
that, pretty clever and compact.. :)

regardless, I don't think this should set yet-another-cache of
_detected_build_type / SetBuildType though, this gets hairy too quickly...
perhaps just GetMostRecentHostBinary(file_name) would be enough? and agree with
frank, move it out into its own module..

[Philippe, 2013/11/05 09:22:13]

Agreed. I moved this to utils/host_path_finder.py. Nice function indeed. I like
the fact that there is no branch in it (especially true in Python :)).

+    """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
+    self_detected_build_type = None
+    out_dir = os.path.join(
+        constants.DIR_SOURCE_ROOT, os.environ.get('CHROMIUM_OUT_DIR', 'out'))
+
+    if constants.BuildTypeIsSet():
+      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
+        self_detected_build_type = 'Release'
+      else:
+        candidate_path = debug_path
+        self_detected_build_type = 'Debug'
+
+    if not os.path.exists(candidate_path):
+      raise Exception('File %s does not exist' % candidate_path)
+
+    if self_detected_build_type:
+      constants.SetBuildType(build_type)
+      logging.warning('Build type set to ' + self_detected_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 +1479,7 @@ class AndroidCommands(object):
     """
     usage_dict = collections.defaultdict(int)
     smaps = collections.defaultdict(dict)
+    self._PurgeUnpinnedAshmem()
     current_smap = ''
     for line in self.GetProtectedFileContents('/proc/%s/smaps' % pid,
                                               log_result=False):