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Commit 84be783f authored by John Dias's avatar John Dias
Browse files

SF: delay region sampling when short on time 

In a number of janky traces, particularly at high
frame rates, we've seen the surfaceflinger thread
overrunning its time slot. In some of those cases,
the surfaceflinger thread is doing region-sampling.
This change causes region-sampling to check how much
time is left until the next vsync before deciding
whether to sample this frame. If low on time,
it will defer the sampling to a later frame.

Bug: 133779857
Test: trace inspection from scrolling in various apps
Change-Id: I92c2368e80033c1ba6e27f947a456d14db02064c
parent 7fbb0831

services/surfaceflinger/RegionSamplingThread.cpp

+19 −4
Original line number Original line Diff line number Diff line
@@ -44,11 +44,14 @@ constexpr auto lumaSamplingStepTag = "LumaSamplingStep"; 
enum class samplingStep {

enum class samplingStep {

    noWorkNeeded,

    noWorkNeeded,

    idleTimerWaiting,

    idleTimerWaiting,

    waitForQuietFrame,

    waitForZeroPhase,

    waitForZeroPhase,

    waitForSamplePhase,

    waitForSamplePhase,

    sample

    sample

};

};





constexpr auto timeForRegionSampling = 5000000ns;

constexpr auto maxRegionSamplingSkips = 10;

constexpr auto defaultRegionSamplingOffset = -3ms;

constexpr auto defaultRegionSamplingOffset = -3ms;

constexpr auto defaultRegionSamplingPeriod = 100ms;

constexpr auto defaultRegionSamplingPeriod = 100ms;

constexpr auto defaultRegionSamplingTimerTimeout = 100ms;

constexpr auto defaultRegionSamplingTimerTimeout = 100ms;
@@ -215,9 +218,9 @@ void RegionSamplingThread::removeListener(const sp<IRegionSamplingListener>& lis 
void RegionSamplingThread::checkForStaleLuma() {

void RegionSamplingThread::checkForStaleLuma() {

    std::lock_guard lock(mThreadControlMutex);

    std::lock_guard lock(mThreadControlMutex);





    if (mDiscardedFrames) {

    if (mDiscardedFrames > 0) {

        ATRACE_INT(lumaSamplingStepTag, static_cast<int>(samplingStep::waitForZeroPhase));

        ATRACE_INT(lumaSamplingStepTag, static_cast<int>(samplingStep::waitForZeroPhase));

        mDiscardedFrames = false;

        mDiscardedFrames = 0;

        mPhaseCallback->startVsyncListener();

        mPhaseCallback->startVsyncListener();

    }

    }

}

}
@@ -235,13 +238,25 @@ void RegionSamplingThread::doSample() { 
    auto now = std::chrono::nanoseconds(systemTime(SYSTEM_TIME_MONOTONIC));

    auto now = std::chrono::nanoseconds(systemTime(SYSTEM_TIME_MONOTONIC));

    if (lastSampleTime + mTunables.mSamplingPeriod > now) {

    if (lastSampleTime + mTunables.mSamplingPeriod > now) {

        ATRACE_INT(lumaSamplingStepTag, static_cast<int>(samplingStep::idleTimerWaiting));

        ATRACE_INT(lumaSamplingStepTag, static_cast<int>(samplingStep::idleTimerWaiting));

        mDiscardedFrames = true;

        if (mDiscardedFrames == 0) mDiscardedFrames++;

        return;

        return;

    }

    }

    if (mDiscardedFrames < maxRegionSamplingSkips) {

        // If there is relatively little time left for surfaceflinger

        // until the next vsync deadline, defer this sampling work

        // to a later frame, when hopefully there will be more time.

        DisplayStatInfo stats;

        mScheduler.getDisplayStatInfo(&stats);

        if (std::chrono::nanoseconds(stats.vsyncTime) - now < timeForRegionSampling) {

            ATRACE_INT(lumaSamplingStepTag, static_cast<int>(samplingStep::waitForQuietFrame));

            mDiscardedFrames++;

            return;

        }

    }





    ATRACE_INT(lumaSamplingStepTag, static_cast<int>(samplingStep::sample));

    ATRACE_INT(lumaSamplingStepTag, static_cast<int>(samplingStep::sample));





    mDiscardedFrames = false;

    mDiscardedFrames = 0;

    lastSampleTime = now;

    lastSampleTime = now;





    mIdleTimer.reset();

    mIdleTimer.reset();

services/surfaceflinger/RegionSamplingThread.h

+1 −1
Original line number Original line Diff line number Diff line
@@ -117,7 +117,7 @@ private: 
    std::condition_variable_any mCondition;

    std::condition_variable_any mCondition;

    bool mRunning GUARDED_BY(mThreadControlMutex) = true;

    bool mRunning GUARDED_BY(mThreadControlMutex) = true;

    bool mSampleRequested GUARDED_BY(mThreadControlMutex) = false;

    bool mSampleRequested GUARDED_BY(mThreadControlMutex) = false;

    bool mDiscardedFrames GUARDED_BY(mThreadControlMutex) = false;

    uint32_t mDiscardedFrames GUARDED_BY(mThreadControlMutex) = 0;

    std::chrono::nanoseconds lastSampleTime GUARDED_BY(mThreadControlMutex);

    std::chrono::nanoseconds lastSampleTime GUARDED_BY(mThreadControlMutex);





    std::mutex mSamplingMutex;

    std::mutex mSamplingMutex;