android IO Prefetch原始碼分析

yooooooo發表於2024-08-01

I/O Prefetcher是高通本身提供的一套最佳化方案，可以用在Android手機App冷啟動的時候。本文基於android Q

主要分libqti-iopd、vendor.qti.hardware.iop@2.0-impl、libqti-iopd-client_system、libqti-perfd-client_system、libperfconfig、libqti_performance，編譯後在/vendor/lib/目錄下，其中libqti-iopd、vendor.qti.hardware.iop@2.0-impl為服務端

libqti-perfd-client_system

主要提供perf_get_prop、perf_wait_get_prop等方法，這裡主要呼叫libperfconfig中的方法去讀取配置檔案中的資訊

程式碼路徑：vendor/qcom/proprietary/commonsys-intf/android-perf/mp-ctl/client.cpp

libperfconfig

主要是讀取/vendor/etc/perf/perfconfigstore.xml檔案獲取配置資訊，此檔案時在編譯時複製

vendor/qcom/proprietary/android-perf/configs/XXX/perfconfigstore.xml到vendor/etc/perf/目錄下

程式碼路徑：vendor/qcom/proprietary/android-perf/perf-hal/Perf.h

libqti-iopd-client_system

主要提供perf_io_prefetch_start、perf_io_prefetch_stop、perf_ux_engine_events、perf_ux_engine_trigger方法，這些方法主要呼叫vendor.qti.hardware.iop@2.0-impl中的iopStart、iopStop、uxEngine_events、uxEngine_trigger

程式碼路徑： vendor/qcom/proprietary/commonsys-intf/android-perf/io-p/client.cpp

libqti_performance

vendor/qcom/proprietary/commonsys/android-perf/QPerformance/src/com/qualcomm/qti/Performance.java的jni實現

vendor.qti.hardware.iop@2.0-impl

主要提供iopStart、iopStop和uxEngine_events、uxEngine_trigger方法，是對libqti-iopd的方法的封裝uxEngine_XX會判斷perfconfigstore.xml中vendor.iop.enable_uxe屬性是否為1來判斷是否啟用，如果未啟用則直接返回程式碼路徑： vendor/qcom/proprietary/android-perf/iop-hal/Iop.cpp

libqti-iopd

主要服務端實現庫，見下文分析

程式碼路徑：vendor/qcom/proprietary/android-perf/io-p/io-p.cpp

首先看服務端的實現

IO Prefetcher的初始化

vendor.qti.hardware.iop的實現比較簡單，主要呼叫libqti-iopd中對應方法。在初始化時，開啟libqti-iopd.so庫，然後找到iop_server_init、iop_server_exit、iop_server_submit_request、uxe_server_submit_request四個方法，並呼叫iop_server_init進行初始化。

對應關係如下：

在呼叫iopStart、iopStop和uxEngine_events時，呼叫libqti-iopd中iop_server_submit_request，並傳遞cmd分別為IOP_CMD_PERFLOCK_IOPREFETCH_START、IOP_CMD_PERFLOCK_IOPREFETCH_STOP和UXENGINE_CMD_PERFLOCK_EVENTS的訊息，並放入IOPevqueue佇列中

在呼叫uxEngine_trigger時，呼叫libqti-iopd中uxe_server_submit_request，並傳遞cmd為UXENGINE_CMD_PERFLOCK_TRIGGER的訊息，並放入UXEevqueue佇列中

* vendor/qcom/proprietary/android-perf/iop-hal/Iop.cpp
IIop* HIDL_FETCH_IIop(const char* /* name */) {
    ALOGE("IOP-HAL: inside HIDL_FETCH_IIop");
    Iop *iopObj = new (std::nothrow) Iop();
    ALOGE("IOP-HAL: boot Address of iop object");
    if (iopObj != NULL) {
        iopObj->LoadIopLib();
        ALOGE("IOP-HAL: loading library is done");
        if (iopObj->mHandle.iop_server_init != NULL ) {
            (*(iopObj->mHandle.iop_server_init))();
        }
    }
    return iopObj;
}

//載入libqti-iopd庫，並找到對應的方法
void Iop::LoadIopLib() {
    const char *rc = NULL;
    char buf[PROPERTY_VALUE_MAX];

    if (!mHandle.is_opened) {
         mHandle.dlhandle = dlopen("libqti-iopd.so", RTLD_NOW | RTLD_LOCAL);
         ...
         *(void **) (&mHandle.iop_server_init) = dlsym(mHandle.dlhandle, "iop_server_init");
         ...
         *(void **) (&mHandle.iop_server_exit) = dlsym(mHandle.dlhandle, "iop_server_exit");
         ...
         *(void **) (&mHandle.iop_server_submit_request) = dlsym(mHandle.dlhandle, "iop_server_submit_request");
         ...
         *(void **) (&mHandle.uxe_server_submit_request) = dlsym(mHandle.dlhandle, "uxe_server_submit_request");
         ...
         mHandle.is_opened = true;
    }

    return;
}

真正的初始化:

* vendor/qcom/proprietary/android-perf/io-p/io-p.cpp
int iop_server_init() {
    ...
    //建立IOP服務，進入無限迴圈來等待訊息
    rc1 = pthread_create(&iop_server_thread, NULL, iop_server, NULL);
    ...
    //讀取vendor.iop.enable_uxe是否為1來判斷是否啟用，1則啟用
    if (uxe_disabled()) {
        uxe_prop_disable = 1;
    } else {
        uxe_prop_disable = 0;
        ...
        //建立UXE服務，進入無限迴圈來等待訊息
        rc2 = pthread_create(&uxe_server_thread, NULL, uxe_server, NULL);
        uba_rc = init_uba();
        ...
        uxe_init = true;
    }

    return 1;
...
}

IOP服務訊息處理，從IOPevqueue訊息佇列中獲取訊息並處理:

* vendor/qcom/proprietary/android-perf/io-p/io-p.cpp
static void *iop_server(void *data)
{
    ...
    /* Main loop */
    for (;;) {
       //wait for perflock commands
        EventData *evData = IOPevqueue.Wait();
        ...
        //判斷vendor.post_boot.parsed表示是否為1來判斷系統是否啟動完成
        if(!is_boot_complete())
        {
            QLOGE("io prefetch is disabled waiting for boot_completed");
            continue;
        }
        //建立DB
        if(is_db_init == false)
        {
            if(create_database() == 0)
            {
                //Success
                is_db_init = true;
            }
        }
        ...
        switch (cmd) {
            //uxEngine_events方法實現
            case UXENGINE_CMD_PERFLOCK_EVENTS:
            {
                ...
                break;
            }
            //iopStart方法實現
            case IOP_CMD_PERFLOCK_IOPREFETCH_START:
            {
                ...
                break;
            }
            //iopStop方法實現
            case IOP_CMD_PERFLOCK_IOPREFETCH_STOP:
            {
                stop_capture();
                break;
            }
        }
   }
}

UXE訊息處理，從UXEevqueue佇列中獲取一個訊息，並處理

* vendor/qcom/proprietary/android-perf/io-p/io-p.cpp
static void *uxe_server(void *data)
{
    for (;;) {
        QLOGI("UXEngine: Waiting on uxe_server_submit_req in uxe_server\n");
        EventData *evData = UXEevqueue.Wait();
        if (!evData || !evData->mEvData) {
            continue;
        }
        cmd = evData->mEvType;
        msg = (iop_msg_t *)evData->mEvData;

        switch (cmd) {
            //uxEngine_trigger方法實現
            case UXENGINE_CMD_PERFLOCK_TRIGGER:
            {
                ...
                break;
            }
       }
   }
}

所以可以看出先是建立了一個database，及4個表，原始碼在dblayer.cppDB儲存路徑為/data/vendor/iop/io-prefetcher.db

* vendor/qcom/proprietary/android-perf/io-p/io-prefetch/dblayer.cpp
/******************************************************************************
  DESCRIPTION

     pkg_file_tbl               pkg_tbl
  |-----------------|      |-----------------|
  |  pkg_name       |      |  pkg_name       |
  |  file_name      |      |-----------------|
  |-----------------|      | pkg_use_time    |
  |                 |      | num_of_launches |
  | file_use_ctr    |      |-----------------|
  | file_time_stamp |
  | file_size       |
  | mark_for_delete |
  | file_modify_time|
  | file_iop_size   |
  | study_finish    |
  | mincore_array   |
  | cache_dropped   |
  | disabled        |
  |-----------------|
******************************************************************************/

/******************************************************************************
      ux_pkg_tbl                 ux_lat_tbl
  |--------------------|        |-----------------|
  |  pkg_name          |        |    pkg_name     |
  |  week_day          |        |-----------------|
  |--------------------|        |   bindApp_dur   |
  | pkg_last_use       |        |   disAct_dur    |
  | num_of_launches    |        |  wakeLock_dur   |
  | num_of_sublaunches |        |    memory_st    |
  | timeslot_1_count   |        |    bindApp_ct   |
  | timeslot_2_count   |        | predict_success |
  | timeslot_3_count   |        |   predict_fail  |
  | timeslot_4_count   |        |    not_game     |
  |--------------------|        |-----------------|
******************************************************************************/

iopStart

* vendor/qcom/proprietary/android-perf/io-p/io-p.cpp
case IOP_CMD_PERFLOCK_IOPREFETCH_START:
{
    static bool is_in_recent_list = false;
    char enable_prefetch_property[PROPERTY_VALUE_MAX];
    char enable_prefetch_ofr_property[PROPERTY_VALUE_MAX];
    int enable_prefetcher = 0;
    int enable_prefetcher_ofr = 0;
    //IOP是否啟用
    strlcpy(enable_prefetch_property,perf_get_prop("vendor.enable.prefetch" , "0").value, PROPERTY_VALUE_MAX);
    enable_prefetch_property[PROPERTY_VALUE_MAX-1]='\0';

    enable_prefetcher = strtod(enable_prefetch_property, NULL);

    strlcpy(enable_prefetch_ofr_property,perf_get_prop("vendor.iop.enable_prefetch_ofr" , "0").value, PROPERTY_VALUE_MAX);
    enable_prefetch_ofr_property[PROPERTY_VALUE_MAX-1]='\0';

    enable_prefetcher_ofr = strtod(enable_prefetch_ofr_property, NULL);

    // if PID < 0 consider it as playback operation
    if(msg->pid < 0)
    {
        int ittr = 0;
        char *week_day = NULL;
        week_day = (char *) malloc(6*sizeof(char));
        // Insert package into the table
        if (week_day == NULL) {
           //Malloc failed. Most-probably low on memory.
           break;
        }
        strlcpy(pkg_info.pkg_name,msg->pkg_name,PKG_NAME_LEN);
        strlcpy(tmp_pkg_name,pkg_info.pkg_name,PKG_NAME_LEN);
        bindApp_dur = 0;
        disAct_dur = 0;
        launching = true;
        //更新DB資訊
        time(&pkg_info.last_time_launched);
           //計算week_day：如果時週二~週六，則為true，否則為false
           //time_slot：4~12時，為1
           //12~17時，為2
           //17~21時，為3
           //0~4,21~24,為4
        compute_time_day_slot(week_day, &time_slot);
        QLOGI("UXEngine Updating Details: pkg_name: %s, week_day: %s, time_slot: %d %s\n", pkg_info.pkg_name, week_day, time_slot, tmp_pkg_name);
        //更新ux_pkg_tbl表資訊
        update_ux_pkg_details(pkg_info, week_day, time_slot, 0);
        //更新tracker資訊，當啟啟動應用個數達到12個時，更新ux_lat_tbl資訊，並設定權重為10
        update_palm_table(msg->pkg_name, 0, 1);

        QLOGI("UXEngine finished ux_pkg_details update \n");
        free(week_day);
        is_in_recent_list = false;
        if(!enable_prefetcher)
        {
            QLOGE("io prefetch is disabled");
            break;
        }

        //檢測應用是否在應用歷史列表中
        for(ittr = 0; ittr < IOP_NO_RECENT_APP; ittr++)
        {
            if(0 == strcmp(msg->pkg_name,recent_list[ittr]))
            {
                is_in_recent_list = true;
                QLOGE("is_in_recent_list is TRUE");
                break;
            }
        }
        // 如果在應用歷史列表中，則退出
        if(true == is_in_recent_list)
        {
            QLOGE("io prefetch is deactivate");
            break;
        }
        //假如在應用歷史個數為7，則重置為0
        if(recent_list_cnt == IOP_NO_RECENT_APP)
            recent_list_cnt = 0;

        //複製包名到應用歷史列表中
        strlcpy(recent_list[recent_list_cnt],msg->pkg_name,PKG_LEN);
        recent_list_cnt++;

        stop_capture();
        stop_playback();
        start_playback(msg->pkg_name);
    }
    // if PID > 0 then consider as capture operation
    if(msg->pid > 0)
    {
        if(!enable_prefetcher)
        {
            QLOGE("io prefetch is disabled");
            break;
        }
        if(true == is_in_recent_list)
        {
            QLOGE("io prefetch Capture is deactivated ");
            break;
        }
        stop_capture();
        //關鍵函式，開始進行capture抓取，啟動一個執行緒，呼叫capture_thread
        start_capture(msg->pid,msg->pkg_name,msg->code_path,enable_prefetcher_ofr);
    }

    break;
}

主要在應用啟動時候呼叫IopStart

假如pid小於0，則進行playback操作

生成tmp_pkg_name(在binderApplication中甬道)和pkg_info
計算week_day：如果時週二~週六，則為true，否則為false
計算time_slot：4 ~ 12時，為1； 12 ~ 17時，為2； 17 ~ 21時，為3； 0～4或者21~24,為4
呼叫update_ux_pkg_details更新ux_pkg_tbl表資訊，pkg_use_count和timeslot_count_欄位+1
呼叫update_palm_table更新tracker資訊，當應用kill，則cached為false，當和上次啟動時間小於2s，do_not_launch為true，當應用launch，則cached為true當啟啟動應用個數達到12個時，更新ux_lat_tbl資訊，並設定權重為10，這裡的權重暫未使用
檢測應用是否在應用歷史列表中，如果在應用歷史列表中，則退出；否則，假如應用歷史個數為7，則重置為0，複製包名到應用歷史列表中
呼叫start_playback，啟動一個執行緒，呼叫start_playback_thread假如pid大於0，則進行start_capture操作，這裡主要啟動一個執行緒，然後執行capture_thread

從第6步開始，為IOP流程，1～5為iop和uxe共通

IOP流程關鍵函式為capture_thread和start_playback_thread

* vendor/qcom/proprietary/android-perf/io-p/io-prefetch/list_capture.cpp
void * capture_thread(void * arg) {
    ...
    //獲取polling_enable標示是否啟用，預設為啟用
    property_get("vendor.polling_enable", property, "0");
    polling_enable = atoi(property);
    ATRACE_BEGIN("capture_thread");
    capture_thread_arg * arg_bundle = (capture_thread_arg *)arg;

    //獲取包名：之前的字元
    pkg_len = strlen(arg_bundle->pkg_name);
    i = 0;
    while(i < pkg_len && arg_bundle->pkg_name[i] != ':')
    {
        i++;
    }
    arg_bundle->pkg_name[i] = '\0';
    strlcpy(list_pkg_name,arg_bundle->pkg_name,PKG_NAME_LEN);

    QLOGI("pkg_name  = %s",arg_bundle->pkg_name);

    if(polling_enable)
    {
        //假如開啟輪詢，則迴圈3000/50次get_snapshot，每次休眠50秒
        while (duration_counter < halt_counter) {
            if (halt_thread) goto cleanup;
            QLOGI("Getting snapshot %d\n", arg_bundle->pid);
            //獲取當前pid開啟的檔案描述符,並放入file_list中
            get_snapshot(list_pkg_name,arg_bundle->pid);
            duration_counter++;
            usleep(read_fd_interval_ms * 1000);
        }
    }
    //獲取到程式碼apk、oat位置，路徑為/data/app/××，這裡會掃描並開啟檔案並放入file_list中
    get_priv_code_files(arg_bundle->pkg_name);
    //獲取檔案位置，路徑為/data/user/0/pkg和/data/data/pkg
    get_priv_files(arg_bundle);
    QLOGI("pkg_name = %s total_files = %d ",arg_bundle->pkg_name,total_files);

    // Insert package into the table
    strlcpy(pkg_info.pkg_name,arg_bundle->pkg_name,PKG_NAME_LEN);
    time(&pkg_info.last_time_launched);
    // Update Mincore data
    if(arg_bundle->ofr)
    {
        for(index = 0; index < total_files;index++)
        {
           if(update_mincore_data(file_list[index]) != 0)
           {
               file_list[index]->mincore_array = NULL;
           }
        }
    }
    //更新在database中，更新io_pkg_tbl,主要更新應用最後啟動時間
    update_pkg_details(pkg_info);
    //更新io_pkg_file_tbl，將開啟的檔案資訊存入資料庫中
    update_file_details(arg_bundle->pkg_name, file_list, total_files);
    delete_mark_files();
cleanup:
    //log a report about how many files need insert or update this time
    QLOGE("# Final entry : pkg_name file_name file_time_stamp filesize file_iop_size");
    for(i = 0; i < total_files; i++) {
        QLOGE("%d. Final entry : %s %s %d %d %d\n",i
                ,arg_bundle->pkg_name,file_list[i]->file_name
                , file_list[i]->file_time_stamp, file_list[i]->filesize, file_list[i]->file_iop_size);
        if (file_list[i]->mincore_array) {
            free(file_list[i]->mincore_array);
            file_list[i]->mincore_array = NULL;
        }
        free(file_list[i]);
    }
    ATRACE_END();

    free(arg_bundle->pkg_name);
    free(arg_bundle);
    QLOGI("Exit capture_thread");
    return NULL;
}

獲取polling_enable標示是否啟用，預設未啟用，如果啟用，則迴圈3000/50次get_snapshot，每次休眠50秒，獲取/proc/pid/fd開啟的檔案描述符,並放入file_list中
獲取包名：之前的字元
獲取到程式碼apk、oat位置，路徑為/data/app/××，這裡會掃描並開啟檔案並放入file_list中
獲取檔案位置，路徑為/data/user/0/pkg和/data/data/pkg，並放入file_list中
更新io_pkg_tbl，主要更新應用最後啟動時間
更新io_pkg_file_tbl，將開啟的檔案資訊存入資料庫中

至此，可以看到，在開啟了iop之後，在開啟應用的時候，會檢視該pid開啟的檔案描述符列表，將一些需要開啟的檔案先快取到資料庫中。那麼快取到資料庫中，該怎麼使用?其實就是呼叫start_playback_thread，從資料庫中查詢到對應的檔案，然後進行開啟操作

start的呼叫流程為：

任務歷史中切換應用ActivityTaskManagerService::moveTaskToFrontLocked

---ActivityStackSupervisor::findTaskToMoveToFront--------ActivityStackSupervisor::acquireAppLaunchPerfLock(當TopActivity為空或者DESTROYED)時被呼叫BoostFramework::perfIOPrefetchStart

應用啟動RootActivityContainer::findTask----ActivityDisplay::findTaskLocked--------ActivityDisplay::acquireAppLaunchPerfLock------------BoostFramework::perfIOPrefetchStar

最終呼叫com.qualcomm.qti.Performance.perfIOPrefetchStart，直接呼叫hidl的iopStart方法及com.qualcomm.qti.UxPerformance.perfIOPrefetchStart 這裡會透過MappedByteBuffer和FileChannel開啟/data/app/下的檔案對映到虛擬記憶體中

uxEngine_events

呼叫流程

ActivityThread::handleBindApplication完成後，呼叫ux_perf.perfUXEngine_events(BoostFramework.UXE_EVENT_BINDAPP, 0,pkg_name,bindApp_dur,//handleBindApplication執行時間pkgDir);//data/app/pck/base.apk

ActivityManagerService::appDiedLockedmUxPerf.perfUXEngine_events(BoostFramework.UXE_EVENT_KILL, 0, app.processName, 0);

ProcessRecord::killux_perf.perfUXEngine_events(BoostFramework.UXE_EVENT_KILL, 0, this.processName, 0);activity顯示完成，呼叫ActivityMetricsLogger.logAppDisplayed

mUxPerf.perfUXEngine_events(BoostFramework.UXE_EVENT_DISPLAYED_ACT, 0, info.packageName, info.windowsDrawnDelayMs);

case UXENGINE_CMD_PERFLOCK_EVENTS:
 {
     if(uxe_prop_disable || !is_boot_complete())
     {
         QLOGE("UXEngine is disabled");
         break;
     }

     int opcode = msg->opcode;
     char in_pkg_name[PKG_NAME_LEN];
     strlcpy(in_pkg_name, msg->pkg_name, PKG_NAME_LEN);

     //Opcode = 2 : Client is sending bindApp duration
     if(opcode == UXE_EVENT_BINDAPP)
     {
         ...
         bindApp_dur = msg->lat;
         //獲取bindApplication次數
         bindApp_count = get_total_pkg_bindapp_count(in_pkg_name);
         QLOGI("UXEngine: Received bindApp duration: %d pkg_name %s tmp_pkg_name: %s\n",
                                                 bindApp_dur, in_pkg_name, tmp_pkg_name);
         if (bindApp_count) {
             int lat_thres = 0;
             //獲取ux_lat_tbl表中資訊
             get_ux_lat_pkg(in_pkg_name, &ux_lat);
             QLOGI("UXEngine: Average bindApp before: %d bindApp_count : %d\n",
                                            ux_lat.bindApp_dur, bindApp_count);
             //計算lat_thres，為當前binderApplication時間和上次時間百分比
             if (ux_lat.bindApp_dur != 0)
                  lat_thres = (bindApp_dur*100)/ux_lat.bindApp_dur;
             //如果lat_thres為[50, 500]之間，且小於4s，則計算平均啟動時間
             if (ux_lat.bindApp_dur != 0 && (LAT_LOW_THRESHOLD < lat_thres && LAT_HIGH_THRESHOLD > lat_thres) && bindApp_dur < 4000) {
                 avg_bindApp = ((bindApp_count) * ux_lat.bindApp_dur + bindApp_dur) / (bindApp_count+1);
             } else {
                 avg_bindApp = ux_lat.bindApp_dur;
                 if (ux_lat.bindApp_dur == 0)
                     avg_bindApp = bindApp_dur;
             }
             avg_disAct = ux_lat.disAct_dur;
             QLOGI("UXEngine: Average bindApp: %d for app: %s bindApp_count: %d\n",
                                          avg_bindApp, in_pkg_name, bindApp_count);
             bindApp_dur = avg_bindApp;
         } else {
             avg_disAct = 0;
         }
         //這種情況下為沒有呼叫過iopStart，即為啟動empty app情況下，
         //比如清除任務後，透過uxEngine_trigger獲取資訊後呼叫startActivityAsUserEmpty情況下
         if (!pkg_match)
         {
             // Empty app launch. Update db table.
             QLOGI("UXEngine: Updating bindApp duration: %d pkg_name %s\n",
                                                 bindApp_dur, in_pkg_name);
             update_ux_lat_details(in_pkg_name, bindApp_dur, avg_disAct, 0, 1);
             bindApp_dur = 0;
             avg_bindApp = 0;
             avg_disAct = 0;
         }
     }

     //Opcode = 3 : Client is sending DisplayedActivity
     if (opcode == UXE_EVENT_DISPLAYED_ACT)
     {
                int non_empty_launch = 1;
                bool pkg_match = true;
                if (tmp_pkg_name[0] == 0)
                    goto disAct_cleanup;
                //比較in_pkg_name和tmp_pkg_name(在IopStart獲取)是否一致 ，launching(IopStart時賦為true)是否為true
                if (!strncmp(in_pkg_name, tmp_pkg_name, PKG_NAME_LEN)) {
                    pkg_match = true;
                } else {
                    //Received unexpected displayed activity.
                    //Update regardless, but for the correct app.
                    //skip update
                    QLOGI("UXEngine: Skip. Received weird DA: %s\n", in_pkg_name);
                    goto disAct_cleanup;
                }

                disAct_dur = msg->lat;
                //呼叫get_total_pkg_use_count查詢ux_pkg_tbl表中pkg_use_count，即應用activity開啟次數
                pkg_count = get_total_pkg_use_count(in_pkg_name);
                // Empty app launch
                //呼叫iopStart，但是未執行binderApplication流程，則bindApp_dur為0，launching為true
                if ((bindApp_dur == 0 && launching) || !pkg_match) {
                    QLOGI("UXEngine: Empty app launch. Just update DA. pkg_name: %s \n", in_pkg_name);
                    bindApp_count = get_total_pkg_bindapp_count(in_pkg_name);
                    get_ux_lat_pkg(in_pkg_name, &ux_lat);
                    // Launching process would have definitely had a bindApp.
                    // If count=0, something wrong. Skip update.
                    if(bindApp_count)
                        bindApp_dur = ux_lat.bindApp_dur;
                    else
                        goto disAct_cleanup;
                    avg_disAct = ux_lat.disAct_dur;
                    //空app啟動流程，曾經被uxe拉起過
                    non_empty_launch = 0;
                }

                QLOGI("UXEngine: bindApp duration: %d, DisplayedActivity: %d\n", bindApp_dur, disAct_dur);
                //代表應用activity被開啟過兩次以上
                if (pkg_count - 1) {
                    QLOGI("UXEngine: Average displayed activity before: %d pkg_count :%d\n", avg_disAct, pkg_count);
                    int lat_thres = 0;
                    if (avg_disAct != 0)
                        lat_thres = (disAct_dur*100)/avg_disAct;
                    if (avg_disAct != 0 && pkg_count != 0 && (LAT_LOW_THRESHOLD < lat_thres && LAT_HIGH_THRESHOLD > lat_thres) && disAct_dur < 5000) {
                        avg_disAct = ((pkg_count - 1) * avg_disAct + disAct_dur) / pkg_count;
                        disAct_dur = avg_disAct;
                    }
                    QLOGI("UXEngine: Average displayed activity after: %d, bindApp_count: %d\n", avg_disAct);
                    if(avg_disAct != 0)
                        disAct_dur = avg_disAct;
                }
                QLOGI("UXEngine: Updating bindApp & DA duration: %d %d pkg_name %s\n",
                                                     bindApp_dur, disAct_dur, in_pkg_name);
                update_ux_lat_details(in_pkg_name, bindApp_dur, disAct_dur, 0, non_empty_launch);

                disAct_cleanup:
                // Refresh preferred apps & palm table after launch.
                        char *final_out[PREFERRED_APP_COUNT];
                        int uba_return = 0, i = 0;
                        for (i = 0; i < PREFERRED_APP_COUNT; i++) {
                            final_out[i] = (char*) malloc(PKG_NAME_LEN);
                            final_out[i][0] = '\0';
                        }
                        uba_return = get_preferred_apps(final_out, 0, NULL, -1, true);
                        update_palm_table(in_pkg_name, 0, 1);
                        //Cleanup
                        for (i = 0; i < PREFERRED_APP_COUNT; i++) {
                            free(final_out[i]);
                        }
                        disAct_dur = 0;
                        bindApp_dur = 0;
                        avg_bindApp = 0;
                        avg_disAct = 0;
                        pkg_count = 0;
                        launching = false;
                        memset(tmp_pkg_name, 0, PKG_NAME_LEN);
                        QLOGI("UXEngine: Finished ux_lat update & reset \n");
     }
     //應用被殺，則更新tracker及資訊ux_lat_tbl資訊
     if(opcode == UXE_EVENT_KILL)
     {
         QLOGI("UXEngine: Received app no-AM kill: %s\n", in_pkg_name);
         update_palm_table(in_pkg_name, 1, 0);
     }

     if(opcode == UXE_EVENT_GAME)
     {
          char *week_day = NULL;
          week_day = (char *) malloc(6*sizeof(char));
           if (week_day == NULL) {
              //Malloc failed. Most-probably low on memory.
              break;
           }
           strlcpy(pkg_info.pkg_name,in_pkg_name,PKG_NAME_LEN);
           time(&pkg_info.last_time_launched);
           compute_time_day_slot(week_day, &time_slot);
           QLOGI("UXEngine Updating sub_launch details: \
                  pkg_name: %s, week_day: %s, time_slot: %d %s\n",
                  pkg_info.pkg_name, week_day, time_slot, tmp_pkg_name);
           update_ux_pkg_details(pkg_info, week_day, time_slot, 1);
           update_palm_table(msg->pkg_name, 0, 1);
           free(week_day);
     }
     if(opcode == UXE_EVENT_SUB_LAUNCH)
     {
         ...
     }
     //應用解除安裝，刪除db資訊
     if(opcode == UXE_EVENT_PKG_UNINSTALL)
     {
         QLOGI("UXEngine: Received pkg uninstall - %s\n", in_pkg_name);
         int userId = msg->lat;
         update_palm_table(in_pkg_name, 1, 0);
         uninstall_pkg(in_pkg_name);
     }
     if(opcode == UXE_EVENT_PKG_INSTALL)
     {
         ...
     }
     break;
 }

UXE_EVENT_BINDAPP 流程，在應用bindApplication完成後呼叫

比較in_pkg_name和tmp_pkg_name(在IopStart獲取)是否一致，launching(IopStart時賦為true)是否為true

呼叫get_total_pkg_bindapp_count查詢ux_lat_tbl表中bindApp_ct獲取bindApplication次數

呼叫get_ux_lat_pkg獲取ux_lat_tbl表中資訊

計算lat_thres，為當前binderApplication時間和上次時間百分比，如果lat_thres為[50, 500]之間，且小於4s，則計算平均啟動時間bindApp_dur

沒有呼叫過iopStart(即tmp_pkg_name為上次iopStart時應用包名)，即為啟動empty app情況下，比如清除任務後，透過uxEngine_trigger獲取資訊後呼叫startActivityAsUserEmpty情況下，則呼叫update_ux_lat_details更新ux_lat_tbl表中bindApp_dur(平均binderApplication時間)和disAct_dur(如果第一次為0，否則為db中儲存的)資訊，並使bindApp_ct+1

UXE_EVENT_DISPLAYED_ACT流程，在應用activity啟動完成後，類似activity啟動的displayed時間

比較in_pkg_name和tmp_pkg_name(在IopStart獲取)是否一致，launching(IopStart時賦為true)是否為true

呼叫get_total_pkg_use_count查詢ux_pkg_tbl表中pkg_use_count，即應用activity開啟次數

呼叫iopStart，但是未執行binderApplication流程，則bindApp_dur為0，launching為true，即為空app啟動流程，曾經被uxe拉起過。呼叫get_total_pkg_bindapp_count獲取ux_lat_tbl中bindApp_ct，即binderApplication次數，呼叫get_ux_lat_pkg獲取ux_lat_tbl中對應包名的資訊，這裡貌似有點雞肋，get_total_pkg_bindapp_count為多餘的。並之non_empty_launch為0，代表空app啟動流程

pkg_count - 1為真，代表應用activity被開啟過兩次以上，

計算lat_thres，為當前displayed activity時間和上次時間百分比，如果lat_thres為[50, 500]之間，且小於5s，則計算平均啟動時間disAct_dur

呼叫update_ux_lat_details更新ux_lat_tbl表中bindApp_dur(平均binderApplication時間)和disAct_dur(如果第一次為0，否則為db中儲存的)資訊，並使bindApp_ct+1(曾經被uxe拉起過，則non_empty_launch為0，不+1)

狀態重置：呼叫get_preferred_apps更新tracker列表呼叫update_palm_table設定為以啟動模式(cached為true)

UXE_EVENT_KILL流程，應用被殺死後的流程

呼叫update_palm_table，設定tracker列表的cached和empty為false

如果kill時間距離displayed activity時間或者返回home時間間隔2s內，則do_not_launch為true，在下次返回home或者displayed時，從返回列表中移除

uxEngine_trigger

獲取需要預啟動的app資訊

case UXENGINE_CMD_PERFLOCK_TRIGGER:
{
    static int back_to_home = 1;
    pa_ready = false;
    //判斷是否啟用
    if(uxe_prop_disable || !is_boot_complete())
    {
        QLOGI("UXEngine is disabled");
        pthread_cond_signal(&ux_trigger_cond);
        break;
    }
    ...
    // get_preferred_apps.
    if(msg->opcode == UXE_TRIGGER || msg->opcode == UXE_ULMK_TRIGGER)
    {
        ...
        QLOGE("UXEngine, Received back to home");
           //final_out個數為12
        char *final_out[PREFERRED_APP_COUNT];
        int uba_return = 0, i = 0;

        for (i = 0; i < PREFERRED_APP_COUNT; i++) {
            final_out[i] = (char*) malloc(PKG_NAME_LEN);
            final_out[i][0] = '\0';
        }

        if (msg->opcode == UXE_TRIGGER) {
            uba_return = get_preferred_apps(final_out, 0, NULL, -1, false);
        } else {
            uba_return = get_preferred_apps(final_out, 1, NULL, -1, false);
        }
        QLOGE("Final OUTPUT: Preferred Apps returned : %d\n", uba_return);

        for (i = 0; i < uba_return ; i++) {
            if (final_out[i][0] != 0) {
                QLOGI("Final OUTPUT: Apps returned: %s\n", final_out[i]);
                strlcat(preferred_apps,final_out[i],strcat_sz);
                strlcat(preferred_apps,"/",strcat_sz);
            }
        }
        pa_ready = true;
        // return to F/W once HIDL is implemented
        back_to_home = 1;
        for (i = 0; i < PREFERRED_APP_COUNT; i++) {
            free(final_out[i]);
        }
        QLOGE("UXEngine: Set preferred apps in uxe_server: %s\n", preferred_apps);
        pthread_cond_signal(&ux_trigger_cond);
    }
    else if (msg->opcode == UXE_TRIGGER_LIST_FAV_APPS) {
        //暫未使用
        ...
    }
    break;
}

* vendor/qcom/proprietary/android-perf/io-p/io-prefetch/uba.cpp
int get_preferred_apps(char **out_list, int disable_palm, char * all_week_day, int all_time_slot, bool launch)
{
    long cur_time = (long) now_secs();
    char *week_day = NULL;
    pkg_ux_top_details *cur_list = NULL;
    int total_pkgs = 0, index = 0, table_size = 0, num_pkgs = 0;
    //臨時個數為18
    int tmp_size = PREFERRED_APP_COUNT + PREFERRED_APP_COUNT/2;
    //week_day為true或者false
    week_day = (char *) malloc(6*sizeof(char));
    if (week_day == NULL) {
        //Malloc failed. Most-probably low on memory.
        goto out;
    }
    //計算week_day：如果時週二~週六，則為true，否則為false
    //time_slot：4~12時，為1
    //12~17時，為2
    //17~21時，為3
    //0~4,21~24,為4
    compute_time_day_slot(week_day, &time_slot);
    //獲取ux_pkg_tbl中應用個數
    total_pkgs = get_total_ux_pkgs(0);

    if (total_pkgs == 0) {
        goto out;
    }
    cur_list = (pkg_ux_top_details *) malloc ((tmp_size+1) * sizeof(pkg_ux_top_details));

    if (cur_list == NULL) {
        goto out;
    }

    QLOGI("Get_Preferred_Apps: Current Time stats: Week_day: %s, Time_slot: %d, Total_pkgs: %d\n", week_day, time_slot, total_pkgs);
    //根據time_slot獲取ux_pkg_tbl中應用列表，即所有記錄的應用的binderApplication時間，開啟次數等資訊
    if (disable_palm == 1 && all_week_day != NULL && all_time_slot != -1)
        num_pkgs = get_top_ux_pkg_list(cur_list, all_week_day, all_time_slot, tmp_size, 1);
    else
        num_pkgs = get_top_ux_pkg_list(cur_list, week_day, time_slot, tmp_size, 1);
    QLOGI("Get_Preferred_Apps: Get Top pkg list Returned pkgs: %d\n", num_pkgs);

    if (num_pkgs == 0) {
        goto out;
    }

    for (index = 0 ; (index < PREFERRED_APP_COUNT && index < num_pkgs) ; index++) {
         int total_count = cur_list[index].num_launches;
         int tslot_count = cur_list[index].timeslot_count_select;
         QLOGI("Get_Preferred_Apps: Accessing cur list: %s pkg_launch_count: %d bindApp_dur: %d disAct_dur%d\n", cur_list[index].pkg_name, cur_list[index].num_launches,
                                                                                                                cur_list[index].bindApp_dur, cur_list[index].disAct_dur);
         strlcpy(out_list[index], cur_list[index].pkg_name, PKG_NAME_LEN);
         QLOGI("Get_Preferred_Apps: Accessing copied list: %s\n", out_list[index]);
         table_size++;
    }

    if (disable_palm == 0) {
        QLOGI("Get_Preferred_Apps: Accessing table_size %d\n", table_size);
        set_palm_table(out_list, table_size, cur_time, launch);
    }
    else if (disable_palm == 1) {
        QLOGI("Get_Preferred_Apps: Return all Fav apps List with size = %d\n", table_size);
    }

out:
    if (cur_list != NULL) {
        free(cur_list);
    }
    if (week_day != NULL) {
        free(week_day);
    }
    return table_size;
}

呼叫邏輯為：清除後臺任務

ActivityStackSupervisor::removeTaskByIdLocked----ActivityStackSupervisor::cleanUpRemovedTaskLocked-------PreferredAppsTask::doInBackground-------------BoostFramework::perfUXEngine_trigger

切換到launcher介面

ActivityStack::resumeTopActivityInnerLocked----PreferredAppsTask::doInBackground

切換到home或者進入任務列表

ActivityRecord::completeResumeLocked----PreferredAppsTask::doInBackground

get_preferred_apps根據應用的啟動時間和星期幾，來預測要啟動的應用，DB中只儲存12個應用當透過perfUXEngine_trigger獲取到應用資訊後，呼叫startActivityAsUserEmpty來啟動一個空的應用，在再次啟動時，直接跳過binderApplication階段，從而加快啟動速度，這裡startActivityAsUserEmpty直接呼叫startProcessLocked建立一個程序，並執行bindApplication流程，因為startProcessLocked時，指定啟動空activity（傳入new HostingRecord(null)），從而在RootActivityContainer::attachApplication時，不在呼叫realStartActivityLocked

* frameworks/base/services/core/java/com/android/server/wm/ActivityStackSupervisor.java
class PreferredAppsTask extends AsyncTask<Void, Void, Void> {
        @Override
        protected Void doInBackground(Void... params) {
            String res = null;
            final Intent intent = new Intent(Intent.ACTION_MAIN);
            int trimLevel = 0;
            try {
                trimLevel = ActivityManager.getService().getMemoryTrimLevel();
            } catch (RemoteException e) {
                return null;
            }
            if (mUxPerf != null
                   && trimLevel < ProcessStats.ADJ_MEM_FACTOR_CRITICAL) {
                res = mUxPerf.perfUXEngine_trigger(BoostFramework.UXE_TRIGGER); 
                if (res == null)
                    return null;
                String[] p_apps = res.split("/");
                if (p_apps.length != 0) {
                    ArrayList<String> apps_l = new ArrayList(Arrays.asList(p_apps));
                    Bundle bParams = new Bundle();
                    if (bParams == null)
                        return null;
                    bParams.putStringArrayList("start_empty_apps", apps_l);
                    final Message msg = PooledLambda.obtainMessage(
                                            ActivityManagerInternal::startActivityAsUserEmpty, mService.mAmInternal, bParams);
                    mService.mH.sendMessage(msg);
                }
            }
            return null;
        }
    }

get_preferred_apps的主要流程為：

呼叫compute_time_day_slot計算當前是否工作日和時間段
根據工作日和時間段呼叫get_top_ux_pkg_list獲取ux_pkg_tbl和ux_lat_tbl中的應用啟動次數(pkg_use_count)，啟動時間(bindApp_dur、disAct_dur)、時間段啟動次數(timeslot_count_)等資訊
獲取到最大PREFERRED_APP_COUNT(12)個應用資訊，放入out_list

呼叫set_palm_table進行應用資訊過濾，並更新tracker列表

int set_palm_table(char **list, int tb_size, long cur_time, bool launch) {
//Compare old and new list, and send update to PALM
//Check for empty conditions.
int i = 0, j = 0, match = 0, match_cached = 0;

 palm_table *cur_tracker;
 palm_table *tmp_tracker;
 cur_tracker = (palm_table *) malloc (tb_size * sizeof(palm_table));

 if (cur_tracker == NULL) {
     QLOGE("Set_Palm_Table: No memory to set temp table. Return");
     return 0;
 }

 QLOGI("Set_Palm_Table: Entry, Table size: %d, old table size: %d, Current time: %ld \n", tb_size, old_tbl_size, cur_time);
 for(i = 0; i < tb_size; i++)
 {
      strlcpy(cur_tracker[i].pkg_name, list[i], PKG_NAME_LEN);
      cur_tracker[i].cached = launch;
      cur_tracker[i].empty = !launch;
      cur_tracker[i].memory_rss = 0; //Use getMemory or db call later on.
      cur_tracker[i].last_empty_time = cur_time;
      cur_tracker[i].do_not_launch = false;
      cur_tracker[i].hit = false;
      cur_tracker[i].comp = false;
      QLOGI("Set_Palm_Table: %s", cur_tracker[i].pkg_name);
      for(j = 0; j < old_tbl_size; j++)
      {
          if(!strncmp(tracker[j].pkg_name, list[i], PKG_NAME_LEN))
          {
              cur_tracker[i].memory_rss = tracker[j].memory_rss;
              cur_tracker[i].last_empty_time = tracker[j].last_empty_time;
              cur_tracker[i].cached = tracker[j].cached;
              cur_tracker[i].empty = tracker[j].empty;
              cur_tracker[i].do_not_launch = tracker[j].do_not_launch;
              cur_tracker[i].hit = tracker[j].hit;
              tracker[j].comp = true;
              strlcpy(cur_tracker[i].pkg_name, tracker[j].pkg_name, PKG_NAME_LEN);
              //
              if(launch || tracker[j].empty || tracker[j].cached) {
                  list[i][0] = 0;
                  list[i][1] = '\0';
                  QLOGI("Set_Palm_Table: Matched empty from previous table. Pkg_name: %s Pkg State--Cached: %d, Empty: %d\n", tracker[j].pkg_name, tracker[j].cached, tracker[j].empty);
                  strlcpy(cur_tracker[i].pkg_name, tracker[j].pkg_name, PKG_NAME_LEN);
                  match++;
              }
             //如果應用2s內被殺兩次(do_not_launch為true)
              else if(tracker[j].do_not_launch) {
                  QLOGI("Set_Palm_Table: Not allowed for launch due to looping: %s\n", tracker[j].pkg_name);
                  list[i][0] = 0;
                  list[i][1] = '\0';
                  cur_tracker[i].cached = false;
                  cur_tracker[i].empty = false;
                  cur_tracker[i].do_not_launch = true;
                  if ((cur_time - tracker[j].last_empty_time) > empty_restart_threshold) {
                      cur_tracker[i].do_not_launch = false;
                      QLOGE("Set_Palm_Table: Timeout expired. Allowed to start as empty: %s\n", tracker[j].pkg_name);
                  }
              }
              //應用被殺後，再次返回home會執行此流程，被拉起，將empty付為空
              else {
                  cur_tracker[i].empty = true;
                  cur_tracker[i].cached = false;
                  QLOGI("Set_Palm_Table: Matched, but app was killed. Resetting. Pkg_name: %s Pkg State--Cached: %d, Empty: %d\n", cur_tracker[i].pkg_name, cur_tracker[i].cached, cur_tracker[i].empty);
              }
          }
      }
 }
 old_tbl_size = tb_size;
 //memcpy(tracker, cur_tracker, (tb_size*sizeof(palm_table)));
 tmp_tracker = tracker;
 tracker = cur_tracker;
 free(tmp_tracker);
 if (match == tb_size)
     return 0;
 else
     return (tb_size - match);

}

set_palm_table

根據最新的可能要啟動應用列表，構建一個最新的tracker
如果應用displayed完成，lunch為true，返回home，lunch為false
當應用kill時，被置為true，當返回home時，進入set_palm_table，然後走else流程，將empty置為true，然後被拉起，empty為true
如果應用2s內被殺兩次，則do_not_launch為true
如果應用已啟動，則cached為true
上述四種情況，則從out列表移除
如果是當前時間段不再tracker的應用(comp為false)，（比如工作日/非工作日切換，常用應用個數大於12個時候，使用次數變更到底等），則如果已經啟動，更新預言成功（predict_success）權重+10，否則更新預言失敗（predict_fail）權重pr_launch/PREFERRED_APP_COUNT*10。這裡的predict_success和predict_fail暫未使用，在android R中不在使用

Android 原始碼分析之 AsyncTask 原始碼分析
2019-03-04
Android原始碼
Android Choreographer 原始碼分析
2020-11-02
Android原始碼
Java IO原始碼分析（三）——PipedOutputStream和PipedInputStream
2020-12-11
Java原始碼
Android中IntentService原始碼分析
2019-04-22
AndroidIntent原始碼
Android開源原始碼分析
2018-04-28
Android原始碼
Android 原始碼分析之 EventBus 的原始碼解析
2018-08-06
Android原始碼
Dart 原始碼分析：深入理解 dart:io HttpClient
2019-08-19
Dart原始碼HTTPclient
Android原始碼分析–ArrayMap優化
2019-02-26
Android原始碼優化
Android Sensor原始碼分析總結
2019-03-29
Android原始碼
Android 8.0 原始碼分析 (八) ActivityManagerService
2019-11-07
Android原始碼
Android Jetpack系列——ViewModel原始碼分析
2019-12-15
AndroidJetpackView原始碼
Android 系統原始碼-1：Android 系統啟動流程原始碼分析
2019-01-20
Android原始碼
React Native 0.55.4 Android 原始碼分析（Java層原始碼解析）
2018-09-12
React NativeAndroid原始碼Java
Android Activity啟動流程原始碼分析
2019-02-28
Android原始碼
Android系統原始碼分析之-ContentProvider
2018-11-06
Android原始碼IDE
Android 原始碼分析（二）handler 機制
2019-02-27
Android原始碼
Android系統原始碼分析-事件收集
2019-03-02
Android原始碼事件
Android View 事件分發原始碼分析
2019-03-13
AndroidView事件原始碼
Android 7 原始碼分析系列導讀
2019-03-04
Android原始碼
Android原始碼分析：Activity啟動流程
2018-03-29
Android原始碼
Android View繪製原始碼分析 Measure
2021-09-09
AndroidView原始碼
Android原始碼分析（LayoutInflater.from(this).inflate(resId,null);原始碼解析）
2018-08-20
Android原始碼Null
設計模式（九）——裝飾者模式(io原始碼分析）
2021-02-04
設計模式原始碼
Android Hook框架Xposed原理與原始碼分析
2019-01-16
AndroidHook框架原始碼
Android原始碼分析之備忘錄模式
2019-02-27
Android原始碼模式
Android 外掛化框架 DynamicLoadApk 原始碼分析
2019-03-02
Android框架APK原始碼
Android原始碼分析之View繪製流程
2019-03-01
Android原始碼View
Android 8.0 原始碼分析 (六) BroadcastReceiver 啟動
2019-11-02
Android原始碼AST
Android 8.0 原始碼分析 (五) Service 啟動
2019-10-31
Android原始碼
Android 8.0 原始碼分析 (四) Activity 啟動
2019-10-29
Android原始碼
Android系統原始碼分析-Broadcast傳送
2019-02-19
Android原始碼AST
Flutter之Android層面原始碼分析（一）
2018-03-17
FlutterAndroid原始碼
Flutter Android 端 Activity/Fragment 流程原始碼分析
2021-08-08
FlutterAndroidFragment原始碼
容器類原始碼解析系列（一） ArrayList 原始碼分析——基於最新Android9.0原始碼
2019-04-08
原始碼Android
React Native Android 原始碼分析之前期準備
2018-07-10
React NativeAndroid原始碼
Android系統原始碼分析--Service啟動流程
2018-04-27
Android原始碼
Android Compose 入門,深入底層原始碼分析
2024-04-10
Android原始碼
Android 8.0 原始碼分析 (一) SystemServer 程式啟動
2019-10-26
Android原始碼Server

android IO Prefetch原始碼分析

IO Prefetcher的初始化

iopStart

uxEngine_events

uxEngine_trigger

相關文章