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概述

开机阶段描述

阶段	描述
boot_progress_start	系统进入用户空间，标志着kernel启动完成
boot_progress_preload_start	Zygote启动
boot_progress_preload_end	Zygote结束
boot_progress_system_run	SystemServer ready,开始启动Android系统服务，如PMS，APMS等
boot_progress_pms_start	PMS开始扫描安装的应用
boot_progress_pms_system_scan_start	PMS先行扫描/system目录下的安装包
boot_progress_pms_data_scan_start	PMS扫描/data目录下的安装包
boot_progress_pms_scan_end	PMS扫描结束
boot_progress_pms_ready	PMS就绪
boot_progress_ams_ready	AMS就绪
boot_progress_enable_screen	AMS启动完成后开始激活屏幕，从此以后屏幕才能响应用户的触摸，它在WindowManagerService发出退出开机动画的时间节点之前，而真正退出开机动画还会花费少许时间，具体依赖animation zip 包中的desc.txt。wm_boot_animation_done才是用户感知到的动画结束时间节点
sf_stop_bootanim	SF设置service.bootanim.exit属性值为1，标志系统要结束开机动画了，可以用来跟踪开机动画结尾部分消耗的时间
wm_boot_animation_done	开机动画结束，这一步用户能直观感受到开机结束

一、boot_progress_start

frameworks/base/core/jni/AndroidRuntime.cpp

void AndroidRuntime::start(const char* className, const Vector<String8>& options, bool zygote)
{
    ...
    /*
     * 'startSystemServer == true' means runtime is obsolete and not run from
     * init.rc anymore, so we print out the boot start event here.
     */
    for (size_t i = 0; i < options.size(); ++i) {
        if (options[i] == startSystemServer) {
            primary_zygote = true;
           /* track our progress through the boot sequence */
           const int LOG_BOOT_PROGRESS_START = 3000;
           LOG_EVENT_LONG(LOG_BOOT_PROGRESS_START,  ns2ms(systemTime(SYSTEM_TIME_MONOTONIC)));
        }
    }
    ...
}

---

二、boot_progress_preload_start

---

三、boot_progress_preload_end

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四、boot_progress_system_run

frameworks/base/services/java/com/android/server/SystemServer.java

    private void run() {
        ...
            // Here we go!
            Slog.i(TAG, "Entered the Android system server!");
            final long uptimeMillis = SystemClock.elapsedRealtime();
            EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_SYSTEM_RUN, uptimeMillis);
            if (!mRuntimeRestart) {
                FrameworkStatsLog.write(FrameworkStatsLog.BOOT_TIME_EVENT_ELAPSED_TIME_REPORTED,
                        FrameworkStatsLog
                                .BOOT_TIME_EVENT_ELAPSED_TIME__EVENT__SYSTEM_SERVER_INIT_START,
                        uptimeMillis);
            }
        ...
    }

---

五、boot_progress_pms_start

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

    public PackageManagerService(Injector injector, boolean onlyCore, boolean factoryTest) {
        ...
        mInjector = injector;
        mInjector.bootstrap(this);
        mLock = injector.getLock();
        mInstallLock = injector.getInstallLock();
        LockGuard.installLock(mLock, LockGuard.INDEX_PACKAGES);
        EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_START,
                SystemClock.uptimeMillis());
        ...
    }

---

六、boot_progress_pms_system_scan_start

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

    public PackageManagerService(Injector injector, boolean onlyCore, boolean factoryTest) {
        ...
            long startTime = SystemClock.uptimeMillis();

            EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SYSTEM_SCAN_START,
                    startTime);

            final String bootClassPath = System.getenv("BOOTCLASSPATH");
            final String systemServerClassPath = System.getenv("SYSTEMSERVERCLASSPATH");

            if (bootClassPath == null) {
                Slog.w(TAG, "No BOOTCLASSPATH found!");
            }

            if (systemServerClassPath == null) {
                Slog.w(TAG, "No SYSTEMSERVERCLASSPATH found!");
            }
        ...
    }

---

七、boot_progress_pms_data_scan_start

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

    public PackageManagerService(Injector injector, boolean onlyCore, boolean factoryTest) {
        ...
            // Remove any shared userIDs that have no associated packages
            mSettings.pruneSharedUsersLPw();
            final long systemScanTime = SystemClock.uptimeMillis() - startTime;
            final int systemPackagesCount = mPackages.size();
            Slog.i(TAG, "Finished scanning system apps. Time: " + systemScanTime
                    + " ms, packageCount: " + systemPackagesCount
                    + " , timePerPackage: "
                    + (systemPackagesCount == 0 ? 0 : systemScanTime / systemPackagesCount)
                    + " , cached: " + cachedSystemApps);
            if (mIsUpgrade && systemPackagesCount > 0) {
                //CHECKSTYLE:OFF IndentationCheck
                FrameworkStatsLog.write(FrameworkStatsLog.BOOT_TIME_EVENT_DURATION_REPORTED,
                    BOOT_TIME_EVENT_DURATION__EVENT__OTA_PACKAGE_MANAGER_SYSTEM_APP_AVG_SCAN_TIME,
                    systemScanTime / systemPackagesCount);
                //CHECKSTYLE:ON IndentationCheck
            }
            if (!mOnlyCore) {
                EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_DATA_SCAN_START,
                        SystemClock.uptimeMillis());
                scanDirTracedLI(sAppInstallDir, 0, scanFlags | SCAN_REQUIRE_KNOWN, 0,
                        packageParser, executorService);

            }
        ...
    }

八、boot_progress_pms_scan_end

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

    public PackageManagerService(Injector injector, boolean onlyCore, boolean factoryTest) {
        ...
            // Now that we know all the packages we are keeping,
            // read and update their last usage times.
            mPackageUsage.read(mSettings.mPackages);
            mCompilerStats.read();

            EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SCAN_END,
                    SystemClock.uptimeMillis());
            Slog.i(TAG, "Time to scan packages: "
                    + ((SystemClock.uptimeMillis()-startTime)/1000f)
                    + " seconds");
        ...
    }

---

九、boot_progress_pms_ready

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

    public PackageManagerService(Injector injector, boolean onlyCore, boolean factoryTest) {
        ...
            // can downgrade to reader
            t.traceBegin("write settings");
            mSettings.writeLPr();
            t.traceEnd();
            EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_READY,
                    SystemClock.uptimeMillis());
        ...
    }

---

十、boot_progress_ams_ready

frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java

    public void systemReady(final Runnable goingCallback, @NonNull TimingsTraceAndSlog t) {
        ...****
        t.traceEnd(); // KillProcesses

        Slog.i(TAG, "System now ready");

        EventLogTags.writeBootProgressAmsReady(SystemClock.uptimeMillis());

        t.traceBegin("updateTopComponentForFactoryTest");
        mAtmInternal.updateTopComponentForFactoryTest();
        t.traceEnd();
        ...
    }

---

十一、boot_progress_enable_screen

frameworks/base/services/core/java/com/android/server/wm/ActivityTaskManagerService.java

        @Override
        public void enableScreenAfterBoot(boolean booted) {
            writeBootProgressEnableScreen(SystemClock.uptimeMillis());
            mWindowManager.enableScreenAfterBoot();
            synchronized (mGlobalLock) {
                updateEventDispatchingLocked(booted);
            }
        }

---

十二、sf_stop_bootanim

frameworks/native/services/surfaceflinger/SurfaceFlinger.cpp

void SurfaceFlinger::bootFinished()
{
    ...
    // stop boot animation
    // formerly we would just kill the process, but we now ask it to exit so it
    // can choose where to stop the animation.
    property_set("service.bootanim.exit", "1");

    const int LOGTAG_SF_STOP_BOOTANIM = 60110;
    LOG_EVENT_LONG(LOGTAG_SF_STOP_BOOTANIM,
                   ns2ms(systemTime(SYSTEM_TIME_MONOTONIC)));

    sp<IBinder> input(defaultServiceManager()->getService(String16("inputflinger")));
    ...
}

---

十三、wm_boot_animation_done

frameworks/base/services/core/java/com/android/server/wm/WindowManagerService.java

    private void performEnableScreen() {
        ...
            try {
                IBinder surfaceFlinger = ServiceManager.getService("SurfaceFlinger");
                if (surfaceFlinger != null) {
                    ProtoLog.i(WM_ERROR, "******* TELLING SURFACE FLINGER WE ARE BOOTED!");
                    Parcel data = Parcel.obtain();
                    data.writeInterfaceToken("android.ui.ISurfaceComposer");
                    surfaceFlinger.transact(IBinder.FIRST_CALL_TRANSACTION, // BOOT_FINISHED
                            data, null, 0);
                    data.recycle();
                }
            } catch (RemoteException ex) {
                ProtoLog.e(WM_ERROR, "Boot completed: SurfaceFlinger is dead!");
            }

            EventLogTags.writeWmBootAnimationDone(SystemClock.uptimeMillis());
            Trace.asyncTraceEnd(TRACE_TAG_WINDOW_MANAGER, "Stop bootanim", 0);
            mDisplayEnabled = true;
            ProtoLog.i(WM_DEBUG_SCREEN_ON, "******************** ENABLING SCREEN!");
        ...
    }

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整体框架