Bug 956263 - Add a preference to control the compositor frame-rate. r=mstange

gfx/layers/ipc/CompositorParent.cpp

@@ -526,10 +526,27 @@ CompositorParent::NotifyShadowTreeTransaction(uint64_t aId, bool aIsFirstPaint,
 // DEFAULT_FRAME_RATE in nsRefreshDriver.cpp.
 static const int32_t kDefaultFrameRate = 60;
 
+static int32_t
+CalculateCompositionFrameRate()
+{
+  int32_t compositionFrameRatePref = gfxPlatform::GetPrefLayersCompositionFrameRate();
+  if (compositionFrameRatePref < 0) {
+    // Use the same frame rate for composition as for layout.
+    int32_t layoutFrameRatePref = gfxPlatform::GetPrefLayoutFrameRate();
+    if (layoutFrameRatePref < 0) {
+      // TODO: The main thread frame scheduling code consults the actual
+      // monitor refresh rate in this case. We should do the same.
+      return kDefaultFrameRate;
+    }
+    return layoutFrameRatePref;
+  }
+  return compositionFrameRatePref;
+}
+
 void
 CompositorParent::ScheduleComposition()
 {
-  if (mCurrentCompositeTask) {
+  if (mCurrentCompositeTask || mPaused) {
     return;
   }
 
@@ -538,12 +555,7 @@ CompositorParent::ScheduleComposition()
   if (!initialComposition)
     delta = TimeStamp::Now() - mLastCompose;
 
-  int32_t rate = gfxPlatform::GetPrefLayoutFrameRate();
-  if (rate < 0) {
-    // TODO: The main thread frame scheduling code consults the actual monitor
-    // refresh rate in this case. We should do the same.
-    rate = kDefaultFrameRate;
-  }
+  int32_t rate = CalculateCompositionFrameRate();
 
   // If rate == 0 (ASAP mode), minFrameDelta must be 0 so there's no delay.
   TimeDuration minFrameDelta = TimeDuration::FromMilliseconds(
@@ -630,6 +642,13 @@ CompositorParent::CompositeInTransaction()
                   15 + (int)(TimeStamp::Now() - mExpectedComposeTime).ToMilliseconds());
   }
 #endif
+
+  // 0 -> Full-tilt composite
+  if (gfxPlatform::GetPrefLayersCompositionFrameRate() == 0) {
+    // Special full-tilt composite mode for performance testing
+    ScheduleComposition();
+  }
+
   profiler_tracing("Paint", "Composite", TRACING_INTERVAL_END);
 }
 

gfx/thebes/gfxPlatform.cpp

@@ -2070,6 +2070,7 @@ static bool sPrefLayersScrollGraph = false;
 static bool sPrefLayersEnableTiles = false;
 static bool sLayersSupportsD3D9 = false;
 static int  sPrefLayoutFrameRate = -1;
+static int  sPrefLayersCompositionFrameRate = -1;
 static bool sBufferRotationEnabled = false;
 static bool sComponentAlphaEnabled = true;
 static bool sPrefBrowserTabsRemote = false;
@@ -2098,6 +2099,7 @@ InitLayersAccelerationPrefs()
     sPrefLayersScrollGraph = Preferences::GetBool("layers.scroll-graph", false);
     sPrefLayersEnableTiles = Preferences::GetBool("layers.enable-tiles", false);
     sPrefLayoutFrameRate = Preferences::GetInt("layout.frame_rate", -1);
+    sPrefLayersCompositionFrameRate = Preferences::GetInt("layers.offmainthreadcomposition.frame-rate", -1);
     sBufferRotationEnabled = Preferences::GetBool("layers.bufferrotation.enabled", true);
     sComponentAlphaEnabled = Preferences::GetBool("layers.componentalpha.enabled", true);
     sPrefBrowserTabsRemote = BrowserTabsRemote();
@@ -2217,6 +2219,13 @@ gfxPlatform::GetPrefLayersEnableTiles()
   return sPrefLayersEnableTiles;
 }
 
+int
+gfxPlatform::GetPrefLayersCompositionFrameRate()
+{
+  InitLayersAccelerationPrefs();
+  return sPrefLayersCompositionFrameRate;
+}
+
 bool
 gfxPlatform::BufferRotationEnabled()
 {

gfx/thebes/gfxPlatform.h

@@ -510,6 +510,7 @@ public:
     static bool GetPrefLayersPreferD3D9();
     static bool CanUseDirect3D9();
     static int  GetPrefLayoutFrameRate();
+    static int  GetPrefLayersCompositionFrameRate();
     static bool GetPrefLayersDump();
     static bool GetPrefLayersScrollGraph();
     static bool GetPrefLayersEnableTiles();

modules/libpref/src/init/all.js

@@ -4093,6 +4093,11 @@ pref("layers.scroll-graph", false);
 
 // Set the default values, and then override per-platform as needed
 pref("layers.offmainthreadcomposition.enabled", false);
+// Compositor target frame rate. NOTE: If vsync is enabled the compositor
+// frame rate will still be capped.
+// -1 -> default (match layout.frame_rate or 60 FPS)
+// 0  -> full-tilt mode: Recomposite even if not transaction occured.
+pref("layers.offmainthreadcomposition.frame-rate", -1);
 // Whether to use the deprecated texture architecture rather than the new one.
 pref("layers.use-deprecated-textures", true);
 #ifndef XP_WIN