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

This will help stabilize memory measurements so that memory regressions can't
be hidden when unpinned ashmem gets purged by the kernel.

BUG=311633

Review URL: https://codereview.chromium.org/52833002

git-svn-id: http://src.chromium.org/svn/trunk/src/build@235115 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

android/pylib/android_commands.py

@@ -22,6 +22,9 @@ import time
 import cmd_helper
 import constants
 import screenshot
+
+from utils import host_path_finder
+
 try:
   from pylib import pexpect
 except:
@@ -1418,6 +1421,20 @@ class AndroidCommands(object):
     logging.warning('Could not find disk IO stats.')
     return None
 
+  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 = host_path_finder.GetMostRecentHostPath('purge_ashmem')
+    if not host_path:
+      raise Exception('Could not find the purge_ashmem binary.')
+    device_path = os.path.join(constants.TEST_EXECUTABLE_DIR, 'purge_ashmem')
+    self.PushIfNeeded(host_path, device_path)
+    if self.RunShellCommand(device_path, log_result=True):
+      return
+    raise Exception('Error while purging ashmem.')
+
   def GetMemoryUsageForPid(self, pid):
     """Returns the memory usage for given pid.
 

android/pylib/utils/host_path_finder.py

@@ -0,0 +1,23 @@
+# 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 os
+
+from pylib import constants
+
+
+def GetMostRecentHostPath(file_name):
+  """Returns the most recent existing full path for the given file name.
+
+  Returns: An empty string if no path could be found.
+  """
+  out_dir = os.path.join(
+      constants.DIR_SOURCE_ROOT, os.environ.get('CHROMIUM_OUT_DIR', 'out'))
+  candidate_paths = map(
+      lambda build_type: os.path.join(out_dir, build_type, file_name),
+      ['Debug', 'Release'])
+  candidate_paths = filter(os.path.exists, candidate_paths)
+  candidate_paths = sorted(candidate_paths, key=os.path.getmtime, reverse=True)
+  candidate_paths.append('')
+  return candidate_paths[0]