commit 2739e839f88caa2bda1c072337bced240f103fc4
author Ady Abraham <adyabr@google.com> Mon Feb 14 17:42:00 2022 -0800
committer Ady Abraham <adyabr@google.com> Tue Feb 15 10:57:51 2022 -0800
tree 80b0678a21c4a3f0e8a6acb58e81e4d96c607142
parent 79bb2dc17584347412536f8faa11413b777f5a21

SF: do not latch unsignaled in early offsets

When we are in early offsets we are most likely in client composition
and/or WM animating windows. Avoid latching unsignaled buffers in this
case to avoid jank when an unsignaled buffers block newer transactions
from getting applied in the next frame.

Bug: 205153280
Test: modified TouchLatency app with long draws
Change-Id: Ice5456db1dec1feaf11f6e022a1eaaedfb26781f

services/surfaceflinger/Scheduler/VsyncModulator.cpp

diff --git a/services/surfaceflinger/Scheduler/VsyncModulator.cpp b/services/surfaceflinger/Scheduler/VsyncModulator.cpp
index 245db0f..be57b2a 100644
--- a/services/surfaceflinger/Scheduler/VsyncModulator.cpp
+++ b/services/surfaceflinger/Scheduler/VsyncModulator.cpp
@@ -134,16 +134,27 @@
     return mVsyncConfig;
 }
 
-const VsyncModulator::VsyncConfig& VsyncModulator::getNextVsyncConfig() const {
+auto VsyncModulator::getNextVsyncConfigType() const -> VsyncConfigType {
     // Early offsets are used if we're in the middle of a refresh rate
     // change, or if we recently begin a transaction.
     if (!mEarlyWakeupRequests.empty() || mTransactionSchedule == Schedule::EarlyEnd ||
         mEarlyTransactionFrames > 0 || mRefreshRateChangePending) {
-        return mVsyncConfigSet.early;
+        return VsyncConfigType::Early;
     } else if (mEarlyGpuFrames > 0) {
-        return mVsyncConfigSet.earlyGpu;
+        return VsyncConfigType::EarlyGpu;
     } else {
-        return mVsyncConfigSet.late;
+        return VsyncConfigType::Late;
+    }
+}
+
+const VsyncModulator::VsyncConfig& VsyncModulator::getNextVsyncConfig() const {
+    switch (getNextVsyncConfigType()) {
+        case VsyncConfigType::Early:
+            return mVsyncConfigSet.early;
+        case VsyncConfigType::EarlyGpu:
+            return mVsyncConfigSet.earlyGpu;
+        case VsyncConfigType::Late:
+            return mVsyncConfigSet.late;
     }
 }
 
@@ -176,4 +187,9 @@
     static_cast<void>(updateVsyncConfigLocked());
 }
 
+bool VsyncModulator::isVsyncConfigDefault() const {
+    std::lock_guard<std::mutex> lock(mMutex);
+    return getNextVsyncConfigType() == VsyncConfigType::Late;
+}
+
 } // namespace android::scheduler

services/surfaceflinger/Scheduler/VsyncModulator.h

diff --git a/services/surfaceflinger/Scheduler/VsyncModulator.h b/services/surfaceflinger/Scheduler/VsyncModulator.h
index 2000c54..537cae1 100644
--- a/services/surfaceflinger/Scheduler/VsyncModulator.h
+++ b/services/surfaceflinger/Scheduler/VsyncModulator.h
@@ -109,11 +109,16 @@
 
     [[nodiscard]] VsyncConfigOpt onDisplayRefresh(bool usedGpuComposition);
 
+    [[nodiscard]] bool isVsyncConfigDefault() const;
+
 protected:
     // Called from unit tests as well
     void binderDied(const wp<IBinder>&) override EXCLUDES(mMutex);
 
 private:
+    enum class VsyncConfigType { Early, EarlyGpu, Late };
+
+    VsyncConfigType getNextVsyncConfigType() const REQUIRES(mMutex);
     const VsyncConfig& getNextVsyncConfig() const REQUIRES(mMutex);
     [[nodiscard]] VsyncConfig updateVsyncConfig() EXCLUDES(mMutex);
     [[nodiscard]] VsyncConfig updateVsyncConfigLocked() REQUIRES(mMutex);