Merge "[SurfaceFlinger] Adjust missed frame tracking" into rvc-dev
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index cfaabfc..9c1c7f7 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1028,7 +1028,7 @@
     ATRACE_CALL();
     ALOGV("performSetActiveConfig");
     if (mCheckPendingFence) {
-        if (previousFrameMissed()) {
+        if (previousFramePending()) {
             // fence has not signaled yet. wait for the next invalidate
             mEventQueue->invalidate();
             return true;
@@ -1775,13 +1775,17 @@
     setTransactionFlags(eDisplayTransactionNeeded);
 }
 
-bool SurfaceFlinger::previousFrameMissed(int graceTimeMs) NO_THREAD_SAFETY_ANALYSIS {
-    ATRACE_CALL();
+sp<Fence> SurfaceFlinger::previousFrameFence() NO_THREAD_SAFETY_ANALYSIS {
     // We are storing the last 2 present fences. If sf's phase offset is to be
     // woken up before the actual vsync but targeting the next vsync, we need to check
     // fence N-2
-    const sp<Fence>& fence = mVSyncModulator->getOffsets().sf > 0 ? mPreviousPresentFences[0]
-                                                                  : mPreviousPresentFences[1];
+    return mVSyncModulator->getOffsets().sf > 0 ? mPreviousPresentFences[0]
+                                                : mPreviousPresentFences[1];
+}
+
+bool SurfaceFlinger::previousFramePending(int graceTimeMs) NO_THREAD_SAFETY_ANALYSIS {
+    ATRACE_CALL();
+    const sp<Fence>& fence = previousFrameFence();
 
     if (fence == Fence::NO_FENCE) {
         return false;
@@ -1794,6 +1798,16 @@
     return (fence->getStatus() == Fence::Status::Unsignaled);
 }
 
+nsecs_t SurfaceFlinger::previousFramePresentTime() NO_THREAD_SAFETY_ANALYSIS {
+    const sp<Fence>& fence = previousFrameFence();
+
+    if (fence == Fence::NO_FENCE) {
+        return Fence::SIGNAL_TIME_INVALID;
+    }
+
+    return fence->getSignalTime();
+}
+
 void SurfaceFlinger::populateExpectedPresentTime() {
     DisplayStatInfo stats;
     mScheduler->getDisplayStatInfo(&stats);
@@ -1811,6 +1825,7 @@
             // calculate the expected present time once and use the cached
             // value throughout this frame to make sure all layers are
             // seeing this same value.
+            const nsecs_t lastExpectedPresentTime = mExpectedPresentTime.load();
             populateExpectedPresentTime();
 
             // When Backpressure propagation is enabled we want to give a small grace period
@@ -1821,12 +1836,32 @@
                      (mPropagateBackpressureClientComposition || !mHadClientComposition))
                     ? 1
                     : 0;
-            const TracedOrdinal<bool> frameMissed = {"FrameMissed",
-                                                     previousFrameMissed(
-                                                             graceTimeForPresentFenceMs)};
-            const TracedOrdinal<bool> hwcFrameMissed = {"HwcFrameMissed",
+
+            // Pending frames may trigger backpressure propagation.
+            const TracedOrdinal<bool> framePending = {"PrevFramePending",
+                                                      previousFramePending(
+                                                              graceTimeForPresentFenceMs)};
+
+            // Frame missed counts for metrics tracking.
+            // A frame is missed if the prior frame is still pending. If no longer pending,
+            // then we still count the frame as missed if the predicted present time
+            // was further in the past than when the fence actually fired.
+
+            // Add some slop to correct for drift. This should generally be
+            // smaller than a typical frame duration, but should not be so small
+            // that it reports reasonable drift as a missed frame.
+            DisplayStatInfo stats;
+            mScheduler->getDisplayStatInfo(&stats);
+            const nsecs_t frameMissedSlop = stats.vsyncPeriod / 2;
+            const nsecs_t previousPresentTime = previousFramePresentTime();
+            const TracedOrdinal<bool> frameMissed =
+                    {"PrevFrameMissed",
+                     framePending ||
+                             (previousPresentTime >= 0 &&
+                              (lastExpectedPresentTime < previousPresentTime - frameMissedSlop))};
+            const TracedOrdinal<bool> hwcFrameMissed = {"PrevHwcFrameMissed",
                                                         mHadDeviceComposition && frameMissed};
-            const TracedOrdinal<bool> gpuFrameMissed = {"GpuFrameMissed",
+            const TracedOrdinal<bool> gpuFrameMissed = {"PrevGpuFrameMissed",
                                                         mHadClientComposition && frameMissed};
 
             if (frameMissed) {
@@ -1846,7 +1881,7 @@
                 mGpuFrameMissedCount++;
             }
 
-            if (frameMissed && mPropagateBackpressure) {
+            if (framePending && mPropagateBackpressure) {
                 if ((hwcFrameMissed && !gpuFrameMissed) ||
                     mPropagateBackpressureClientComposition) {
                     signalLayerUpdate();
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 44e18a7..6ab1fcf 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -844,7 +844,21 @@
 
     bool isDisplayConfigAllowed(HwcConfigIndexType configId) const REQUIRES(mStateLock);
 
-    bool previousFrameMissed(int graceTimeMs = 0);
+    // Gets the fence for the previous frame.
+    // Must be called on the main thread.
+    sp<Fence> previousFrameFence();
+
+    // Whether the previous frame has not yet been presented to the display.
+    // If graceTimeMs is positive, this method waits for at most the provided
+    // grace period before reporting if the frame missed.
+    // Must be called on the main thread.
+    bool previousFramePending(int graceTimeMs = 0);
+
+    // Returns the previous time that the frame was presented. If the frame has
+    // not been presented yet, then returns Fence::SIGNAL_TIME_PENDING. If there
+    // is no pending frame, then returns Fence::SIGNAL_TIME_INVALID.
+    // Must be called on the main thread.
+    nsecs_t previousFramePresentTime();
 
     // Populates the expected present time for this frame. For negative offsets, performs a
     // correction using the predicted vsync for the next frame instead.