frameworks/base: Vote to turn off io_is_busy during recording.

When recording starts, vote to turn off io_is_busy. After
recording stops, take out that vote so that io_is_busy can
go to its original value. Doing this saves power by reducing
the amount of time for which the CPU runs at high frequencies
when encoded data is being written to the SD card - a process
that causes io_wait times to shoot up. With io_is_busy turned off,
these wait times will not be considered as CPU busy time and so
the ondemand governor will not unnecessarily bump up the clock rate.
The votes are handled by the CpuGovernorService. Also move the
dynamic sampling rate and vote processor classes out of the
CpuGovernorService to improve modularity.

1 files changed, 37 insertions, 3 deletions

diff --git a/media/java/android/media/MediaRecorder.java b/media/java/android/media/MediaRecorder.java
index 08e6032..2afaea5 100644
--- a/media/java/android/media/MediaRecorder.java
+++ b/media/java/android/media/MediaRecorder.java
@@ -22,6 +22,10 @@ import android.os.Looper;
 import android.os.Message;
 import android.util.Log;
 import android.view.Surface;
+import android.app.Application;
+import android.app.ActivityThread;
+import android.content.Context;
+import android.content.Intent;
 
 import java.io.FileDescriptor;
 import java.io.FileOutputStream;
@@ -76,8 +80,10 @@ public class MediaRecorder
         System.loadLibrary("media_jni");
         native_init();
     }
-    private final static String TAG = "MediaRecorder";
 
+    private final static String TAG = "MediaRecorder";
+    private final static String IOBUSY_VOTE = "com.android.server.CpuGovernorService.action.IOBUSY_VOTE";
+    private final static String IOBUSY_UNVOTE = "com.android.server.CpuGovernorService.action.IOBUSY_UNVOTE";
     // The two fields below are accessed by native methods
     @SuppressWarnings("unused")
     private int mNativeContext;
@@ -654,7 +660,7 @@ public class MediaRecorder
      * @throws IllegalStateException if it is called before
      * prepare().
      */
-    public native void start() throws IllegalStateException;
+    public native void native_start() throws IllegalStateException;
 
     /**
      * Stops recording. Call this after start(). Once recording is stopped,
@@ -668,7 +674,35 @@ public class MediaRecorder
      *
      * @throws IllegalStateException if it is called before start()
      */
-    public native void stop() throws IllegalStateException;
+    public native void native_stop() throws IllegalStateException;
+
+    public void start() throws IllegalStateException {
+        try {
+            Application application = ActivityThread.systemMain().getApplication();
+            Intent ioBusyVoteIntent = new Intent(IOBUSY_VOTE);
+            // Vote for io_is_busy to be turned off.
+            ioBusyVoteIntent.putExtra("com.android.server.CpuGovernorService.voteType", 0);
+            application.sendBroadcast(ioBusyVoteIntent);
+        } catch (Exception exception) {
+            Log.e(TAG, "Unable to vote to turn io_is_busy off.");
+        }
+
+        native_start();
+    }
+
+    public void stop() throws IllegalStateException {
+        try {
+            Application application = ActivityThread.systemMain().getApplication();
+            Intent ioBusyUnVoteIntent = new Intent(IOBUSY_UNVOTE);
+            // Remove vote for io_is_busy to be turned off.
+            ioBusyUnVoteIntent.putExtra("com.android.server.CpuGovernorService.voteType", 0);
+            application.sendBroadcast(ioBusyUnVoteIntent);
+        } catch (Exception exception) {
+            Log.e(TAG, "Unable to withdraw io_is_busy off vote.");
+        }
+
+        native_stop();
+    }
 
     /**
      * Restarts the MediaRecorder to its idle state. After calling