[Android] Support idle wakeup measurement with /proc/timer_stats

tools/telemetry/telemetry/core/platform.py

Index: tools/telemetry/telemetry/core/platform.py
diff --git a/tools/telemetry/telemetry/core/platform.py b/tools/telemetry/telemetry/core/platform.py
index 5a4d750f340d708c96f0be15946743918eea9b5f..cbc4017a9bd2ffc0f9c4f035f2c074553d73eb67 100644
--- a/tools/telemetry/telemetry/core/platform.py
+++ b/tools/telemetry/telemetry/core/platform.py
@@ -223,13 +223,18 @@ class Platform(object):
     """
     return self._platform_backend.CanMonitorPower()
 
+  def CanMeasureIdleWakeUps(self):
+    """Returns True iff idle wakeups can be monitored via
+    StartMeasuringIdleWakeUps() and StopMeasuringIdleWakeUps().
+    """
+    return self._platform_backend.CanMeasureIdleWakeUps()
+
   def CanMeasurePerApplicationPower(self):
     """Returns True if the power monitor can measure power for the target
     application in isolation. False if power measurement is for full system
     energy consumption."""
     return self._platform_backend.CanMeasurePerApplicationPower()
 
-
   def StartMonitoringPower(self, browser):
     """Starts monitoring power utilization statistics.
 
@@ -283,6 +288,16 @@ class Platform(object):
     """
     return self._platform_backend.StopMonitoringPower()
 
+  def StartMeasuringIdleWakeUps(self):
+    """Starts monitoring idle wakeups."""
+    assert self._platform_backend.CanMeasureIdleWakeUps()
+    self._platform_backend.StartMeasuringIdleWakeUps()
+
+  def StopMeasuringIdleWakeUps(self):
+    """Stops monitoring idle wakeups."""

[nednguyen, 2015/07/29 22:22:45]

This does not return any thing? How do the callsites get the idea wakeups data?

[jdduke (slow), 2015/07/29 22:30:03]

Exactly =/. That's why I prefaced this CL with:

"What I'd really like to do is make idle wakeup measurement its own PowerMonitor
instance. We'd have one for Mac, using ps, and one for Android/Linux, using
/proc/timer_stats. Support for multiple PowerMonitors is in the works, and I
think this would eliminate some of the awkwardness of trying to make the Linux
idle measurement approach match that of Mac."

Now, what I could do as an intermediate step, is move the cpu_stats-based delta
measurement for Mac into the Mac backend, and have the /proc/timer_stats
measurement as a separate implementation for the Android backend.

Basically, it seems like the original change from thestig@ was designed to
minimize disruption/changes to how idle wakeups are measured on Mac.

+    assert self._platform_backend.CanMeasureIdleWakeUps()
+    self._platform_backend.StopMeasuringIdleWakeUps()
+
   def CanMonitorNetworkData(self):
     """Returns true if network data can be retrieved, false otherwise."""
     return self._platform_backend.CanMonitorNetworkData()