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Commit 1157930b authored by Ady Abraham's avatar Ady Abraham
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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
parent 03edff5e

services/surfaceflinger/SurfaceFlinger.cpp

+22 −3
Original line number Diff line number Diff line
@@ -1588,7 +1588,8 @@ 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
@@ -1597,7 +1598,15 @@ 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() {
@@ -1620,7 +1629,17 @@ void SurfaceFlinger::onMessageReceived(int32_t what) NO_THREAD_SAFETY_ANALYSIS { 
            // 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",

services/surfaceflinger/SurfaceFlinger.h

+1 −1
Original line number Diff line number Diff line
@@ -780,7 +780,7 @@ private: 


    bool isDisplayConfigAllowed(int32_t configId) const REQUIRES(mStateLock);



    bool previousFrameMissed();

    bool previousFrameMissed(int graceTimeMs = 0);



    // Populates the expected present time for this frame. For negative offsets, performs a

    // correction using the predicted vsync for the next frame instead.