[Telemetry] Add the ability to flush the system file cache to platform.

tools/telemetry/telemetry/core/platform/proc_util.py

Index: tools/telemetry/telemetry/core/platform/proc_util.py
diff --git a/tools/telemetry/telemetry/core/platform/proc_util.py b/tools/telemetry/telemetry/core/platform/proc_util.py
new file mode 100644
index 0000000000000000000000000000000000000000..3f9b22b79024302e64f72d41c812afbb982d7054
--- /dev/null
+++ b/tools/telemetry/telemetry/core/platform/proc_util.py
@@ -0,0 +1,42 @@
+# Copyright (c) 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.
+
+try:
+  import resource  # pylint: disable=F0401
+except ImportError:
+  resource = None  # Not available on all platforms
+
+
+def _ConvertKbToByte(value):
+  return int(value.replace('kB','')) * 1024
+
+def _GetProcFileDict(contents):
+  retval = {}
+  for line in contents.splitlines():
+    key, value = line.split(':')
+    retval[key.strip()] = value.strip()
+  return retval
+
+def GetSystemCommitCharge(meminfo_contents):
+  meminfo = _GetProcFileDict(meminfo_contents)
+  return (_ConvertKbToByte(meminfo['MemTotal'])
+          - _ConvertKbToByte(meminfo['MemFree'])
+          - _ConvertKbToByte(meminfo['Buffers'])
+          - _ConvertKbToByte(meminfo['Cached']))
+
+def GetMemoryStats(status_contents, stats):
+  status = _GetProcFileDict(status_contents)
+  if not status or not stats or 'Z' in status['State']:
+    return {}
+  return {'VM': int(stats[22]),
+          'VMPeak': _ConvertKbToByte(status['VmPeak']),
+          'WorkingSetSize': int(stats[23]) * resource.getpagesize(),
+          'WorkingSetSizePeak': _ConvertKbToByte(status['VmHWM'])}
+
+def GetIOStats(io_contents):
+  io = _GetProcFileDict(io_contents)
+  return {'ReadOperationCount': int(io['syscr']),
+          'WriteOperationCount': int(io['syscw']),
+          'ReadTransferCount': int(io['rchar']),
+          'WriteTransferCount': int(io['wchar'])}