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Commit b40b0269 authored by Ady Abraham's avatar Ady Abraham
Browse files

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
Merged-In: I713fad164fa2f4e0f00a2b4efaae063ac8f4a2b7
parent 5726d926

services/surfaceflinger/SurfaceFlinger.cpp

+20 −3
Original line number Diff line number Diff line
@@ -1676,7 +1676,8 @@ void SurfaceFlinger::updateVrFlinger() { 
    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
@@ -1685,7 +1686,15 @@ bool SurfaceFlinger::previousFrameMissed() NO_THREAD_SAFETY_ANALYSIS { 
            ? 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() NO_THREAD_SAFETY_ANALYSIS {
@@ -1708,7 +1717,15 @@ void SurfaceFlinger::onMessageReceived(int32_t what) NO_THREAD_SAFETY_ANALYSIS { 
            // seeing this same value.

            populateExpectedPresentTime();



            bool 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;

            bool frameMissed = previousFrameMissed(graceTimeForPresentFenceMs);

            bool hwcFrameMissed = mHadDeviceComposition && frameMissed;

            bool gpuFrameMissed = mHadClientComposition && frameMissed;

            ATRACE_INT("FrameMissed", static_cast<int>(frameMissed));

services/surfaceflinger/SurfaceFlinger.h

+1 −1
Original line number Diff line number Diff line
@@ -851,7 +851,7 @@ private: 
        return hwcDisplayId ? getHwComposer().toPhysicalDisplayId(*hwcDisplayId) : std::nullopt;

    }



    bool previousFrameMissed();

    bool previousFrameMissed(int graceTimeMs = 0);

    void setVsyncEnabledInHWC(DisplayId displayId, HWC2::Vsync enabled);



    /*