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Commit f792cfe8 authored by Alec Mouri's avatar Alec Mouri
Browse files

Only apply early offsets when transaction has been applied 

This avoids a race where we decrement the early offset count in
postComposition() before the transaction applying early offsets has
actually been applied, so we're in early offsets for too few frames.

Bug: 158127834
Test: photos launch
Test: systrace

Change-Id: If7a7d12fa466ee4d163210263b7f02f7a74b3280
parent 983e568b

services/surfaceflinger/Scheduler/VSyncModulator.cpp

+13 −3
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <cutils/properties.h>

#include <utils/Trace.h>



#include <chrono>

#include <cinttypes>

#include <mutex>
@@ -52,6 +53,7 @@ void VSyncModulator::setPhaseOffsets(const OffsetsConfig& config) { 
void VSyncModulator::setTransactionStart(Scheduler::TransactionStart transactionStart) {

    if (transactionStart == Scheduler::TransactionStart::EARLY) {

        mRemainingEarlyFrameCount = MIN_EARLY_FRAME_COUNT_TRANSACTION;

        mEarlyTxnStartTime = std::chrono::steady_clock::now();

    }



    // An early transaction stays an early transaction.
@@ -64,6 +66,7 @@ void VSyncModulator::setTransactionStart(Scheduler::TransactionStart transaction 
}



void VSyncModulator::onTransactionHandled() {

    mTxnAppliedTime = std::chrono::steady_clock::now();

    if (mTransactionStart == Scheduler::TransactionStart::NORMAL) return;

    mTransactionStart = Scheduler::TransactionStart::NORMAL;

    updateOffsets();
@@ -87,10 +90,17 @@ void VSyncModulator::onRefreshRateChangeCompleted() { 


void VSyncModulator::onRefreshed(bool usedRenderEngine) {

    bool updateOffsetsNeeded = false;



    // Apply a 1ms margin to account for potential data races

    // This might make us stay in early offsets for one

    // additional frame but it's better to be conservative here.

    static const constexpr std::chrono::nanoseconds kMargin = 1ms;

    if ((mEarlyTxnStartTime.load() + kMargin) < mTxnAppliedTime.load()) {

        if (mRemainingEarlyFrameCount > 0) {

            mRemainingEarlyFrameCount--;

            updateOffsetsNeeded = true;

        }

    }

    if (usedRenderEngine) {

        mRemainingRenderEngineUsageCount = MIN_EARLY_GL_FRAME_COUNT_TRANSACTION;

        updateOffsetsNeeded = true;

services/surfaceflinger/Scheduler/VSyncModulator.h

+3 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 


#pragma once



#include <chrono>

#include <mutex>



#include "Scheduler.h"
@@ -110,6 +111,8 @@ private: 
    std::atomic<bool> mRefreshRateChangePending = false;

    std::atomic<int> mRemainingEarlyFrameCount = 0;

    std::atomic<int> mRemainingRenderEngineUsageCount = 0;

    std::atomic<std::chrono::steady_clock::time_point> mEarlyTxnStartTime = {};

    std::atomic<std::chrono::steady_clock::time_point> mTxnAppliedTime = {};



    bool mTraceDetailedInfo = false;

};