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Commit 99ca3367 authored by Ady Abraham's avatar Ady Abraham
Browse files

SF: ignore very close vsync timestamps 

Check for very close vsync timestamps and mark those
as invalid.

Test: SF unit tests
Bug: 190331974
Change-Id: I13ccc09d6a07847fdfc60242a1a65246fa9674ac
parent 603a15d2

services/surfaceflinger/Scheduler/VSyncPredictor.cpp

+15 −1
Original line number Diff line number Diff line
@@ -69,7 +69,21 @@ bool VSyncPredictor::validate(nsecs_t timestamp) const { 


    auto const aValidTimestamp = mTimestamps[mLastTimestampIndex];

    auto const percent = (timestamp - aValidTimestamp) % mIdealPeriod * kMaxPercent / mIdealPeriod;

    return percent < kOutlierTolerancePercent || percent > (kMaxPercent - kOutlierTolerancePercent);

    if (percent >= kOutlierTolerancePercent &&

        percent <= (kMaxPercent - kOutlierTolerancePercent)) {

        return false;

    }



    const auto iter = std::min_element(mTimestamps.begin(), mTimestamps.end(),

                                       [timestamp](nsecs_t a, nsecs_t b) {

                                           return std::abs(timestamp - a) < std::abs(timestamp - b);

                                       });

    const auto distancePercent = std::abs(*iter - timestamp) * kMaxPercent / mIdealPeriod;

    if (distancePercent < kOutlierTolerancePercent) {

        // duplicate timestamp

        return false;

    }

    return true;

}



nsecs_t VSyncPredictor::currentPeriod() const {

services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp

+22 −0
Original line number Diff line number Diff line
@@ -510,6 +510,28 @@ TEST_F(VSyncPredictorTest, knownVsyncIsUpdated) { 
    EXPECT_EQ(mNow + 1000, tracker.nextAnticipatedVSyncTimeFrom(mNow));

}



TEST_F(VSyncPredictorTest, robustToDuplicateTimestamps_60hzRealTraceData) {

    // these are real vsync timestamps from b/190331974 which caused vsync predictor

    // period to spike to 18ms due to very close timestamps

    std::vector<nsecs_t> const simulatedVsyncs{

            198353408177, 198370074844, 198371400000, 198374274000, 198390941000, 198407565000,

            198540887994, 198607538588, 198624218276, 198657655939, 198674224176, 198690880955,

            198724204319, 198740988133, 198758166681, 198790869196, 198824205052, 198840871678,

            198857715631, 198890885797, 198924199640, 198940873834, 198974204401,

    };

    auto constexpr idealPeriod = 16'666'666;

    auto constexpr expectedPeriod = 16'644'742;

    auto constexpr expectedIntercept = 125'626;



    tracker.setPeriod(idealPeriod);

    for (auto const& timestamp : simulatedVsyncs) {

        tracker.addVsyncTimestamp(timestamp);

    }

    auto [slope, intercept] = tracker.getVSyncPredictionModel();

    EXPECT_THAT(slope, IsCloseTo(expectedPeriod, mMaxRoundingError));

    EXPECT_THAT(intercept, IsCloseTo(expectedIntercept, mMaxRoundingError));

}



} // namespace android::scheduler



// TODO(b/129481165): remove the #pragma below and fix conversion issues