HWC2: Backpressure missed vsyncs into apps
Adds a mechanism to detect whether the prior frame SurfaceFlinger
presented to hardware composer was actually picked up or not. We then
use this mechanism to avoid pushing two frames in the same vsync.
This backpressure is passed back to applications by not latching any
buffers, which will manifest as dequeueBuffer stalling until
SurfaceFlinger releases a buffer on the following vsync.
Also makes the former INVALIDATE_ON_VSYNC behavior the only behavior
so that this functionality works correctly.
Bug: 29413700
Change-Id: Ibde358e45423ee6fea7b5e09ff65e49c4ad67baa
diff --git a/services/surfaceflinger/MessageQueue.cpp b/services/surfaceflinger/MessageQueue.cpp
index 34dc24b..974c7a3 100644
--- a/services/surfaceflinger/MessageQueue.cpp
+++ b/services/surfaceflinger/MessageQueue.cpp
@@ -134,31 +134,12 @@
}
-/* when INVALIDATE_ON_VSYNC is set SF only processes
- * buffer updates on VSYNC and performs a refresh immediately
- * after.
- *
- * when INVALIDATE_ON_VSYNC is set to false, SF will instead
- * perform the buffer updates immediately, but the refresh only
- * at the next VSYNC.
- * THIS MODE IS BUGGY ON GALAXY NEXUS AND WILL CAUSE HANGS
- */
-#define INVALIDATE_ON_VSYNC 1
-
void MessageQueue::invalidate() {
-#if INVALIDATE_ON_VSYNC
mEvents->requestNextVsync();
-#else
- mHandler->dispatchInvalidate();
-#endif
}
void MessageQueue::refresh() {
-#if INVALIDATE_ON_VSYNC
mHandler->dispatchRefresh();
-#else
- mEvents->requestNextVsync();
-#endif
}
int MessageQueue::cb_eventReceiver(int fd, int events, void* data) {
@@ -172,11 +153,7 @@
while ((n = DisplayEventReceiver::getEvents(mEventTube, buffer, 8)) > 0) {
for (int i=0 ; i<n ; i++) {
if (buffer[i].header.type == DisplayEventReceiver::DISPLAY_EVENT_VSYNC) {
-#if INVALIDATE_ON_VSYNC
mHandler->dispatchInvalidate();
-#else
- mHandler->dispatchRefresh();
-#endif
break;
}
}
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 9a2747d..c541668 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -167,9 +167,6 @@
property_get("ro.bq.gpu_to_cpu_unsupported", value, "0");
mGpuToCpuSupported = !atoi(value);
- property_get("debug.sf.drop_missed_frames", value, "0");
- mDropMissedFrames = atoi(value);
-
property_get("debug.sf.showupdates", value, "0");
mDebugRegion = atoi(value);
@@ -933,6 +930,14 @@
bool SurfaceFlinger::handleMessageInvalidate() {
ATRACE_CALL();
+ bool frameMissed = !mHadClientComposition &&
+ mPreviousPresentFence != Fence::NO_FENCE &&
+ mPreviousPresentFence->getSignalTime() == INT64_MAX;
+ ATRACE_INT("FrameMissed", static_cast<int>(frameMissed));
+ if (frameMissed) {
+ signalLayerUpdate();
+ return false;
+ }
return handlePageFlip();
}
@@ -940,36 +945,22 @@
ATRACE_CALL();
nsecs_t refreshStartTime = systemTime(SYSTEM_TIME_MONOTONIC);
- static nsecs_t previousExpectedPresent = 0;
- nsecs_t expectedPresent = mPrimaryDispSync.computeNextRefresh(0);
- static bool previousFrameMissed = false;
- bool frameMissed = (expectedPresent == previousExpectedPresent);
- if (frameMissed != previousFrameMissed) {
- ATRACE_INT("FrameMissed", static_cast<int>(frameMissed));
- }
- previousFrameMissed = frameMissed;
- if (CC_UNLIKELY(mDropMissedFrames && frameMissed)) {
- // Latch buffers, but don't send anything to HWC, then signal another
- // wakeup for the next vsync
- preComposition();
- repaintEverything();
- } else {
- preComposition();
- rebuildLayerStacks();
- setUpHWComposer();
- doDebugFlashRegions();
- doComposition();
- postComposition(refreshStartTime);
- }
+ preComposition();
+ rebuildLayerStacks();
+ setUpHWComposer();
+ doDebugFlashRegions();
+ doComposition();
+ postComposition(refreshStartTime);
+
+ mPreviousPresentFence = mHwc->getRetireFence(HWC_DISPLAY_PRIMARY);
+ mHadClientComposition = mHwc->hasClientComposition(HWC_DISPLAY_PRIMARY);
// Release any buffers which were replaced this frame
for (auto& layer : mLayersWithQueuedFrames) {
layer->releasePendingBuffer();
}
mLayersWithQueuedFrames.clear();
-
- previousExpectedPresent = mPrimaryDispSync.computeNextRefresh(0);
}
void SurfaceFlinger::doDebugFlashRegions()
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 28666e2..0df39a4 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -468,7 +468,6 @@
RenderEngine* mRenderEngine;
nsecs_t mBootTime;
bool mGpuToCpuSupported;
- bool mDropMissedFrames;
sp<EventThread> mEventThread;
sp<EventThread> mSFEventThread;
sp<EventControlThread> mEventControlThread;
@@ -488,6 +487,8 @@
bool mAnimCompositionPending;
#ifdef USE_HWC2
std::vector<sp<Layer>> mLayersWithQueuedFrames;
+ sp<Fence> mPreviousPresentFence = Fence::NO_FENCE;
+ bool mHadClientComposition = false;
#endif
// this may only be written from the main thread with mStateLock held
diff --git a/services/surfaceflinger/SurfaceFlinger_hwc1.cpp b/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
index 83f7b08..d84d4e1 100644
--- a/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
+++ b/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
@@ -166,9 +166,6 @@
property_get("ro.bq.gpu_to_cpu_unsupported", value, "0");
mGpuToCpuSupported = !atoi(value);
- property_get("debug.sf.drop_missed_frames", value, "0");
- mDropMissedFrames = atoi(value);
-
property_get("debug.sf.showupdates", value, "0");
mDebugRegion = atoi(value);
@@ -944,30 +941,13 @@
ATRACE_CALL();
nsecs_t refreshStartTime = systemTime(SYSTEM_TIME_MONOTONIC);
- static nsecs_t previousExpectedPresent = 0;
- nsecs_t expectedPresent = mPrimaryDispSync.computeNextRefresh(0);
- static bool previousFrameMissed = false;
- bool frameMissed = (expectedPresent == previousExpectedPresent);
- if (frameMissed != previousFrameMissed) {
- ATRACE_INT("FrameMissed", static_cast<int>(frameMissed));
- }
- previousFrameMissed = frameMissed;
- if (CC_UNLIKELY(mDropMissedFrames && frameMissed)) {
- // Latch buffers, but don't send anything to HWC, then signal another
- // wakeup for the next vsync
- preComposition();
- repaintEverything();
- } else {
- preComposition();
- rebuildLayerStacks();
- setUpHWComposer();
- doDebugFlashRegions();
- doComposition();
- postComposition(refreshStartTime);
- }
-
- previousExpectedPresent = mPrimaryDispSync.computeNextRefresh(0);
+ preComposition();
+ rebuildLayerStacks();
+ setUpHWComposer();
+ doDebugFlashRegions();
+ doComposition();
+ postComposition(refreshStartTime);
}
void SurfaceFlinger::doDebugFlashRegions()