SurfaceFlinger: VSyncPredictor should be robust with inconsistent vsyncs
If VSyncPredictor gets an invalid timestamp, it might be accepted as
a correct one, and then all the other correct timestamps will become
incorrect for VSyncPredictor leading to rejecting all the correct
timestamps followed by a one off inconsistent vsync.
Bug: 173235499
Test: SF unit tests (+1 new)
Change-Id: I192b917196c727b9a97a0d18bae160467f75722d
diff --git a/services/surfaceflinger/Scheduler/VSyncPredictor.cpp b/services/surfaceflinger/Scheduler/VSyncPredictor.cpp
index 75d1e6f..a28ed92 100644
--- a/services/surfaceflinger/Scheduler/VSyncPredictor.cpp
+++ b/services/surfaceflinger/Scheduler/VSyncPredictor.cpp
@@ -77,8 +77,12 @@
if (!validate(timestamp)) {
// VSR could elect to ignore the incongruent timestamp or resetModel(). If ts is ignored,
- // don't insert this ts into mTimestamps ringbuffer.
- if (!mTimestamps.empty()) {
+ // don't insert this ts into mTimestamps ringbuffer. If we are still
+ // in the learning phase we should just clear all timestamps and start
+ // over.
+ if (mTimestamps.size() < kMinimumSamplesForPrediction) {
+ clearTimestamps();
+ } else if (!mTimestamps.empty()) {
mKnownTimestamp =
std::max(timestamp, *std::max_element(mTimestamps.begin(), mTimestamps.end()));
} else {
diff --git a/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp b/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp
index 3d60479..a142022 100644
--- a/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp
@@ -475,6 +475,20 @@
}
}
+TEST_F(VSyncPredictorTest, InconsistentVsyncValueIsFlushedEventually) {
+ EXPECT_TRUE(tracker.addVsyncTimestamp(600));
+ EXPECT_TRUE(tracker.needsMoreSamples());
+
+ EXPECT_FALSE(tracker.addVsyncTimestamp(mNow += mPeriod));
+
+ for (auto i = 0u; i < kMinimumSamplesForPrediction; i++) {
+ EXPECT_TRUE(tracker.needsMoreSamples());
+ EXPECT_TRUE(tracker.addVsyncTimestamp(mNow += mPeriod));
+ }
+
+ EXPECT_FALSE(tracker.needsMoreSamples());
+}
+
} // namespace android::scheduler
// TODO(b/129481165): remove the #pragma below and fix conversion issues
