SurfaceFlinger: add grace time for present fence to signal
To avoid racing with HWVsync when SF wakeup at a small offset from vsync,
we want to give a small grace period for the present fence to fire
instead of just giving up on this frame.
Bug: 141312250
Test: Set SF offset to 0 and observe systrace
Change-Id: I713fad164fa2f4e0f00a2b4efaae063ac8f4a2b7
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 997234f..83832b9 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1588,7 +1588,8 @@
setTransactionFlags(eDisplayTransactionNeeded);
}
-bool SurfaceFlinger::previousFrameMissed() NO_THREAD_SAFETY_ANALYSIS {
+bool SurfaceFlinger::previousFrameMissed(int graceTimeMs) NO_THREAD_SAFETY_ANALYSIS {
+ ATRACE_CALL();
// 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
@@ -1597,7 +1598,15 @@
? mPreviousPresentFences[0]
: mPreviousPresentFences[1];
- return fence != Fence::NO_FENCE && (fence->getStatus() == Fence::Status::Unsignaled);
+ if (fence == Fence::NO_FENCE) {
+ return false;
+ }
+
+ if (graceTimeMs > 0 && fence->getStatus() == Fence::Status::Unsignaled) {
+ fence->wait(graceTimeMs);
+ }
+
+ return (fence->getStatus() == Fence::Status::Unsignaled);
}
void SurfaceFlinger::populateExpectedPresentTime() {
@@ -1620,7 +1629,17 @@
// seeing this same value.
populateExpectedPresentTime();
- const TracedOrdinal<bool> frameMissed = {"FrameMissed", previousFrameMissed()};
+ // When Backpressure propagation is enabled we want to give a small grace period
+ // for the present fence to fire instead of just giving up on this frame to handle cases
+ // where present fence is just about to get signaled.
+ const int graceTimeForPresentFenceMs =
+ (mPropagateBackpressure &&
+ (mPropagateBackpressureClientComposition || !mHadClientComposition))
+ ? 1
+ : 0;
+ const TracedOrdinal<bool> frameMissed = {"FrameMissed",
+ previousFrameMissed(
+ graceTimeForPresentFenceMs)};
const TracedOrdinal<bool> hwcFrameMissed = {"HwcFrameMissed",
mHadDeviceComposition && frameMissed};
const TracedOrdinal<bool> gpuFrameMissed = {"GpuFrameMissed",