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..d81f20c8520022cd742ca41707f8c5ea01a25b47 100644
--- a/build/android/pylib/android_commands.py
+++ b/build/android/pylib/android_commands.py
@@ -21,6 +21,9 @@ import time
 
 import cmd_helper
 import constants
+
+from utils import host_path_finder
+
 try:
   from pylib import pexpect
 except:
@@ -1409,6 +1412,19 @@ class AndroidCommands(object):
     logging.warning('Could not find disk IO stats.')
     return None
 
+  def _PurgeUnpinnedAshmem(self):

[bulach, 2013/11/05 16:25:14]

probably best to make this public and let callers decide whether or not they
want to purge, wdyt?
(and it can also be done just once rather than per pid)

[Philippe, 2013/11/05 16:37:42]

Yeah, good idea. I don't think many clients will need to have ashmem purged so
it's probably ok if we let the client deal with this detail (which he will
certainly miss but again clients other than Telemetry should not have to worry
too much about this).
I did not find an easy/not too hackish way for doing it only once though.

+    """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 host_path:
+      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
+    logging.error('Could not purge ashmem. Measurement might be unstable.')
+
   def GetMemoryUsageForPid(self, pid):
     """Returns the memory usage for given pid.
 
@@ -1425,6 +1441,7 @@ 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):