CleanFlight 源码分析一，任务调度

CleanerFlight的任务调度用的是时间片查询的方式。每个任务没有自己的堆栈，不会进行强行跳转。任何一个任务时间过长都会导致其它任务时间延迟(所以不要乱用Delay()).

A.基本的调度方式，如果当前系统时间 > (任务的最后一次运行时间+任务的运行周期),则执行当前任务，否则继续查找到期的任务。

B.任务优先级，先查询优先级数字低的任务，A, 遍历完所有任务后，下个优先级

C.任务可以是事件驱动型，或者是周期型，或者两者都是。先执行事件驱动，然后是周期运行。

D.系统时间，微秒计时。设置systick的中断时间为1毫秒，中断内负责毫秒计时，则

微秒计数=毫秒计数 * 1000 + (系统时钟频率 / 1000 - systick计数值) / (系统时钟频率 / 1000000)

E.执行任务，使用函数指针指向当前任务函数，加入输入变量即可运行：selectedTask->taskFunc(currentTimeUs)，

系统工作步骤：

1.初始化任务列表

2.任务循环调度

任务系统就两个文件：scheduler.h,scheduler.c

自定义任务：

[TASK_SERIAL] = {
.taskName = "SERIAL",
.taskFunc = taskHandleSerial,
#ifdef USE_OSD_SLAVE
.checkFunc = taskSerialCheck,
.desiredPeriod = TASK_PERIOD_HZ(100),
.staticPriority = TASK_PRIORITY_REALTIME,
#else
.desiredPeriod = TASK_PERIOD_HZ(1), // 100 Hz should be enough to flush up to 115 bytes @ 115200 baud
.staticPriority = TASK_PRIORITY_LOW,
#endif
},

任务内容：

void taskHandleSerial()
{
Serial_puts(USART3, "HELLODWORLD\n"); /*while (1);*/
}

允许任务运行：

setTaskEnabled(TASK_SERIAL, true);

任务开始：

void schedulerInit(void)
{
calculateTaskStatistics = true;
queueClear();
queueAdd(&cfTasks[TASK_SYSTEM]);
}

任务调度：

void scheduler(void)
{
// Cache currentTime
const timeUs_t currentTimeUs = micros();

// Check for realtime tasks
bool outsideRealtimeGuardInterval = true;
for (const cfTask_t *task = queueFirst(); task != NULL && task->staticPriority >= TASK_PRIORITY_REALTIME; task = queueNext())
{
const timeUs_t nextExecuteAt = task->lastExecutedAt + task->desiredPeriod;
if ((timeDelta_t)(currentTimeUs - nextExecuteAt) >= 0)
{
outsideRealtimeGuardInterval = false;
break;
}
}

// The task to be invoked
cfTask_t *selectedTask = NULL;
uint16_t selectedTaskDynamicPriority = 0;

// Update task dynamic priorities
uint16_t waitingTasks = 0;
for (cfTask_t *task = queueFirst(); task != NULL; task = queueNext())
{
// Task has checkFunc - event driven
if (task->checkFunc)
{
#if defined(SCHEDULER_DEBUG)
const timeUs_t currentTimeBeforeCheckFuncCall = micros();
#else
const timeUs_t currentTimeBeforeCheckFuncCall = currentTimeUs;
#endif
// Increase priority for event driven tasks
if (task->dynamicPriority > 0)
{
task->taskAgeCycles = 1 + ((currentTimeUs - task->lastSignaledAt) / task->desiredPeriod);
task->dynamicPriority = 1 + task->staticPriority * task->taskAgeCycles;
waitingTasks++;
}
else if (task->checkFunc(currentTimeBeforeCheckFuncCall, currentTimeBeforeCheckFuncCall - task->lastExecutedAt))
{
#if defined(SCHEDULER_DEBUG)
DEBUG_SET(DEBUG_SCHEDULER, 3, micros() - currentTimeBeforeCheckFuncCall);
#endif
#ifndef SKIP_TASK_STATISTICS
if (calculateTaskStatistics)
{
const uint32_t checkFuncExecutionTime = micros() - currentTimeBeforeCheckFuncCall;
checkFuncMovingSumExecutionTime += checkFuncExecutionTime - checkFuncMovingSumExecutionTime / MOVING_SUM_COUNT;
checkFuncTotalExecutionTime += checkFuncExecutionTime; // time consumed by scheduler + task
checkFuncMaxExecutionTime = MAX(checkFuncMaxExecutionTime, checkFuncExecutionTime);
}
#endif
task->lastSignaledAt = currentTimeBeforeCheckFuncCall;
task->taskAgeCycles = 1;
task->dynamicPriority = 1 + task->staticPriority;
waitingTasks++;
} else
{
task->taskAgeCycles = 0;
}
}
else
{
// Task is time-driven, dynamicPriority is last execution age (measured in desiredPeriods)
// Task age is calculated from last execution
task->taskAgeCycles = ((currentTimeUs - task->lastExecutedAt) / task->desiredPeriod);
if (task->taskAgeCycles > 0) {
task->dynamicPriority = 1 + task->staticPriority * task->taskAgeCycles;
waitingTasks++;
}
}

if (task->dynamicPriority > selectedTaskDynamicPriority) {
const bool taskCanBeChosenForScheduling =
(outsideRealtimeGuardInterval) ||
(task->taskAgeCycles > 1) ||
(task->staticPriority == TASK_PRIORITY_REALTIME);
if (taskCanBeChosenForScheduling) {
selectedTaskDynamicPriority = task->dynamicPriority;
selectedTask = task;
}
}
}

totalWaitingTasksSamples++;
totalWaitingTasks += waitingTasks;

currentTask = selectedTask;

if (selectedTask)
{
// Found a task that should be run
selectedTask->taskLatestDeltaTime = currentTimeUs - selectedTask->lastExecutedAt;
selectedTask->lastExecutedAt = currentTimeUs;
selectedTask->dynamicPriority = 0;

// Execute task
#ifdef SKIP_TASK_STATISTICS
selectedTask->taskFunc(currentTimeUs);
#else
if (calculateTaskStatistics)
{
const timeUs_t currentTimeBeforeTaskCall = micros();
selectedTask->taskFunc(currentTimeBeforeTaskCall);
const timeUs_t taskExecutionTime = micros() - currentTimeBeforeTaskCall;
selectedTask->movingSumExecutionTime += taskExecutionTime - selectedTask->movingSumExecutionTime / MOVING_SUM_COUNT;
selectedTask->totalExecutionTime += taskExecutionTime; // time consumed by scheduler + task
selectedTask->maxExecutionTime = MAX(selectedTask->maxExecutionTime, taskExecutionTime);
} else {
selectedTask->taskFunc(currentTimeUs);
}

#endif
#if defined(SCHEDULER_DEBUG)
DEBUG_SET(DEBUG_SCHEDULER, 2, micros() - currentTimeUs - taskExecutionTime); // time spent in scheduler
} else {
DEBUG_SET(DEBUG_SCHEDULER, 2, micros() - currentTimeUs);
#endif
}

GET_SCHEDULER_LOCALS();
}

main函数

int main()

{

systemInit();

fcTasksInit();
while (true) {
scheduler();

}

运行效果

/*
 * This file is part of Cleanflight.
 *
 * Cleanflight is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Cleanflight is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
 */

#pragma once
#include "stm32f30x.h"
#define STATIC_UNIT_TESTED static
#define UNUSED(x) (void)(x)
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define ABS(x) ((x) > 0 ? (x) : -(x))
#define SCHEDULER_DELAY_LIMIT 1
#define GET_SCHEDULER_LOCALS() {}
// time difference, 32 bits always sufficient

typedef int32_t timeDelta_t;
// millisecond time
typedef uint32_t timeMs_t;
// microsecond time
typedef uint32_t timeUs_t;
typedef enum {
    TASK_PRIORITY_IDLE = 0,     // Disables dynamic scheduling, task is executed only if no other task is active this cycle
    TASK_PRIORITY_LOW = 1,
    TASK_PRIORITY_MEDIUM = 3,
    TASK_PRIORITY_MEDIUM_HIGH = 4,
    TASK_PRIORITY_HIGH = 5,
    TASK_PRIORITY_REALTIME = 6,
    TASK_PRIORITY_MAX = 255
} cfTaskPriority_e;

typedef struct {
    timeUs_t     maxExecutionTime;
    timeUs_t     totalExecutionTime;
    timeUs_t     averageExecutionTime;
} cfCheckFuncInfo_t;

typedef struct {
    const char * taskName;
    const char * subTaskName;
    bool         isEnabled;
    uint8_t      staticPriority;
    timeDelta_t  desiredPeriod;
    timeDelta_t  latestDeltaTime;
    timeUs_t     maxExecutionTime;
    timeUs_t     totalExecutionTime;
    timeUs_t     averageExecutionTime;
} cfTaskInfo_t;

typedef enum ActualTasks {
    /* Actual tasks */
    TASK_SYSTEM = 0,
    //TASK_GYROPID,
    //TASK_ACCEL,
    //TASK_ATTITUDE,
    //TASK_RX,
    TASK_SERIAL,
    //TASK_DISPATCH,
    //TASK_BATTERY_VOLTAGE,
    //TASK_BATTERY_CURRENT,
    //TASK_BATTERY_ALERTS,
#ifdef BEEPER
    TASK_BEEPER,
#endif
#ifdef GPS
    TASK_GPS,
#endif
#ifdef MAG
    TASK_COMPASS,
#endif
#ifdef BARO
    TASK_BARO,
#endif
#ifdef SONAR
    TASK_SONAR,
#endif
#if defined(BARO) || defined(SONAR)
    TASK_ALTITUDE,
#endif
#ifdef USE_DASHBOARD
    TASK_DASHBOARD,
#endif
#ifdef TELEMETRY
    TASK_TELEMETRY,
#endif
#ifdef LED_STRIP
    TASK_LEDSTRIP,
#endif
#ifdef TRANSPONDER
    TASK_TRANSPONDER,
#endif
#ifdef STACK_CHECK
    TASK_STACK_CHECK,
#endif
#ifdef OSD
    TASK_OSD,
#endif
#ifdef USE_OSD_SLAVE
    TASK_OSD_SLAVE,
#endif
#ifdef USE_BST
    TASK_BST_MASTER_PROCESS,
#endif
#ifdef USE_ESC_SENSOR
    TASK_ESC_SENSOR,
#endif
#ifdef CMS
    TASK_CMS,
#endif
#ifdef VTX_CONTROL
    TASK_VTXCTRL,
#endif

#ifdef USE_RCSPLIT
    TASK_RCSPLIT,
#endif
    /* Count of real tasks */
    TASK_COUNT,

    /* Service task IDs */
    TASK_NONE = TASK_COUNT,
    TASK_SELF
} cfTaskId_e;

typedef struct {
    // Configuration
    const char * taskName;
    const char * subTaskName;
    bool (*checkFunc)(timeUs_t currentTimeUs, timeDelta_t currentDeltaTimeUs);
    void (*taskFunc)(timeUs_t currentTimeUs);
    timeDelta_t desiredPeriod;      // target period of execution
    const uint8_t staticPriority;   // dynamicPriority grows in steps of this size, shouldn't be zero

    // Scheduling
    uint16_t dynamicPriority;       // measurement of how old task was last executed, used to avoid task starvation
    uint16_t taskAgeCycles;
    timeDelta_t taskLatestDeltaTime;
    timeUs_t lastExecutedAt;        // last time of invocation
    timeUs_t lastSignaledAt;        // time of invocation event for event-driven tasks

#ifndef SKIP_TASK_STATISTICS
    // Statistics
    timeUs_t movingSumExecutionTime;  // moving sum over 32 samples
    timeUs_t maxExecutionTime;
    timeUs_t totalExecutionTime;    // total time consumed by task since boot
#endif
} cfTask_t;

extern cfTask_t cfTasks[TASK_COUNT];
extern uint16_t averageSystemLoadPercent;

void getCheckFuncInfo(cfCheckFuncInfo_t *checkFuncInfo);
void getTaskInfo(cfTaskId_e taskId, cfTaskInfo_t *taskInfo);
void rescheduleTask(cfTaskId_e taskId, uint32_t newPeriodMicros);
void setTaskEnabled(cfTaskId_e taskId, bool newEnabledState);
timeDelta_t getTaskDeltaTime(cfTaskId_e taskId);
void schedulerSetCalulateTaskStatistics(bool calculateTaskStatistics);
void schedulerResetTaskStatistics(cfTaskId_e taskId);

void schedulerInit(void);
void scheduler(void);
void taskSystem(timeUs_t currentTime);

#define LOAD_PERCENTAGE_ONE 100

#define isSystemOverloaded() (averageSystemLoadPercent >= LOAD_PERCENTAGE_ONE)

/*
 * This file is part of Cleanflight.
 *
 * Cleanflight is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Cleanflight is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
 */

#define SRC_MAIN_SCHEDULER_C_

#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include "scheduler.h"
#include "system.h"
//#include "platform.h"
//
//#include "build/build_config.h"
//#include "build/debug.h"
//
//#include "scheduler/scheduler.h"
//
//#include "config/config_unittest.h"
//
//#include "common/maths.h"
//#include "common/time.h"
//#include "common/utils.h"
//
//#include "drivers/time.h"

// DEBUG_SCHEDULER, timings for:
// 0 - gyroUpdate()
// 1 - pidController()
// 2 - time spent in scheduler
// 3 - time spent executing check function

static cfTask_t *currentTask = NULL;

static uint32_t totalWaitingTasks;
static uint32_t totalWaitingTasksSamples;

static bool calculateTaskStatistics;
uint16_t averageSystemLoadPercent = 0;


static int taskQueuePos = 0;
STATIC_UNIT_TESTED int taskQueueSize = 0;

// No need for a linked list for the queue, since items are only inserted at startup

STATIC_UNIT_TESTED cfTask_t* taskQueueArray[TASK_COUNT + 1]; // extra item for NULL pointer at end of queue

void queueClear(void)
{
    memset(taskQueueArray, 0, sizeof(taskQueueArray));
    taskQueuePos = 0;
    taskQueueSize = 0;
}

bool queueContains(cfTask_t *task)
{
    for (int ii = 0; ii < taskQueueSize; ++ii) {
        if (taskQueueArray[ii] == task) {
            return true;
        }
    }
    return false;
}

bool queueAdd(cfTask_t *task)
{
    if ((taskQueueSize >= TASK_COUNT) || queueContains(task)) {
        return false;
    }
    for (int ii = 0; ii <= taskQueueSize; ++ii) {
        if (taskQueueArray[ii] == NULL || taskQueueArray[ii]->staticPriority < task->staticPriority) {
            memmove(&taskQueueArray[ii+1], &taskQueueArray[ii], sizeof(task) * (taskQueueSize - ii));
            taskQueueArray[ii] = task;
            ++taskQueueSize;
            return true;
        }
    }
    return false;
}

bool queueRemove(cfTask_t *task)
{
    for (int ii = 0; ii < taskQueueSize; ++ii) {
        if (taskQueueArray[ii] == task) {
            memmove(&taskQueueArray[ii], &taskQueueArray[ii+1], sizeof(task) * (taskQueueSize - ii));
            --taskQueueSize;
            return true;
        }
    }
    return false;
}

/*
 * Returns first item queue or NULL if queue empty
 */
cfTask_t *queueFirst(void)
{
    taskQueuePos = 0;
    return taskQueueArray[0]; // guaranteed to be NULL if queue is empty
}

/*
 * Returns next item in queue or NULL if at end of queue
 */
cfTask_t *queueNext(void)
{
    return taskQueueArray[++taskQueuePos]; // guaranteed to be NULL at end of queue
}

void taskSystem(timeUs_t currentTimeUs)
{
    UNUSED(currentTimeUs);

    // Calculate system load
    if (totalWaitingTasksSamples > 0) {
        averageSystemLoadPercent = 100 * totalWaitingTasks / totalWaitingTasksSamples;
        totalWaitingTasksSamples = 0;
        totalWaitingTasks = 0;
    }
#if defined(SIMULATOR_BUILD)
    averageSystemLoadPercent = 0;
#endif
}

#ifndef SKIP_TASK_STATISTICS
#define MOVING_SUM_COUNT 32
timeUs_t checkFuncMaxExecutionTime;
timeUs_t checkFuncTotalExecutionTime;
timeUs_t checkFuncMovingSumExecutionTime;

void getCheckFuncInfo(cfCheckFuncInfo_t *checkFuncInfo)
{
    checkFuncInfo->maxExecutionTime = checkFuncMaxExecutionTime;
    checkFuncInfo->totalExecutionTime = checkFuncTotalExecutionTime;
    checkFuncInfo->averageExecutionTime = checkFuncMovingSumExecutionTime / MOVING_SUM_COUNT;
}

void getTaskInfo(cfTaskId_e taskId, cfTaskInfo_t * taskInfo)
{
    taskInfo->taskName = cfTasks[taskId].taskName;
    taskInfo->subTaskName = cfTasks[taskId].subTaskName;
    taskInfo->isEnabled = queueContains(&cfTasks[taskId]);
    taskInfo->desiredPeriod = cfTasks[taskId].desiredPeriod;
    taskInfo->staticPriority = cfTasks[taskId].staticPriority;
    taskInfo->maxExecutionTime = cfTasks[taskId].maxExecutionTime;
    taskInfo->totalExecutionTime = cfTasks[taskId].totalExecutionTime;
    taskInfo->averageExecutionTime = cfTasks[taskId].movingSumExecutionTime / MOVING_SUM_COUNT;
    taskInfo->latestDeltaTime = cfTasks[taskId].taskLatestDeltaTime;
}
#endif

void rescheduleTask(cfTaskId_e taskId, uint32_t newPeriodMicros)
{
    if (taskId == TASK_SELF) 
    {
        cfTask_t *task = currentTask;
        task->desiredPeriod = MAX(SCHEDULER_DELAY_LIMIT, newPeriodMicros);  // Limit delay to 100us (10 kHz) to prevent scheduler clogging
    } 
    else if (taskId < TASK_COUNT) 
    {
        cfTask_t *task = &cfTasks[taskId];
        task->desiredPeriod = MAX(SCHEDULER_DELAY_LIMIT, newPeriodMicros);  // Limit delay to 100us (10 kHz) to prevent scheduler clogging
    }
}

void setTaskEnabled(cfTaskId_e taskId, bool enabled)
{
    if (taskId == TASK_SELF || taskId < TASK_COUNT) {
        cfTask_t *task = taskId == TASK_SELF ? currentTask : &cfTasks[taskId];
        if (enabled && task->taskFunc) {
            queueAdd(task);
        } else {
            queueRemove(task);
        }
    }
}

timeDelta_t getTaskDeltaTime(cfTaskId_e taskId)
{
    if (taskId == TASK_SELF) {
        return currentTask->taskLatestDeltaTime;
    } else if (taskId < TASK_COUNT) {
        return cfTasks[taskId].taskLatestDeltaTime;
    } else {
        return 0;
    }
}

void schedulerSetCalulateTaskStatistics(bool calculateTaskStatisticsToUse)
{
    calculateTaskStatistics = calculateTaskStatisticsToUse;
}

void schedulerResetTaskStatistics(cfTaskId_e taskId)
{
#ifdef SKIP_TASK_STATISTICS
    UNUSED(taskId);
#else
    if (taskId == TASK_SELF) {
        currentTask->movingSumExecutionTime = 0;
        currentTask->totalExecutionTime = 0;
        currentTask->maxExecutionTime = 0;
    } else if (taskId < TASK_COUNT) {
        cfTasks[taskId].movingSumExecutionTime = 0;
        cfTasks[taskId].totalExecutionTime = 0;
        cfTasks[taskId].maxExecutionTime = 0;
    }
#endif
}

void schedulerInit(void)
{
    calculateTaskStatistics = true;
    queueClear();
    queueAdd(&cfTasks[TASK_SYSTEM]);
}

void scheduler(void)
{
    // Cache currentTime
    const timeUs_t currentTimeUs = micros();

    // Check for realtime tasks
    bool outsideRealtimeGuardInterval = true;
    for (const cfTask_t *task = queueFirst(); task != NULL && task->staticPriority >= TASK_PRIORITY_REALTIME; task = queueNext())
    {
        const timeUs_t nextExecuteAt = task->lastExecutedAt + task->desiredPeriod;
        if ((timeDelta_t)(currentTimeUs - nextExecuteAt) >= 0)
        {
            outsideRealtimeGuardInterval = false;
            break;
        }
    }

    // The task to be invoked
    cfTask_t *selectedTask = NULL;
    uint16_t selectedTaskDynamicPriority = 0;

    // Update task dynamic priorities
    uint16_t waitingTasks = 0;
    for (cfTask_t *task = queueFirst(); task != NULL; task = queueNext()) 
    {
        // Task has checkFunc - event driven
        if (task->checkFunc) 
        {
#if defined(SCHEDULER_DEBUG)
            const timeUs_t currentTimeBeforeCheckFuncCall = micros();
#else
            const timeUs_t currentTimeBeforeCheckFuncCall = currentTimeUs;
#endif
            // Increase priority for event driven tasks
            if (task->dynamicPriority > 0)
            {
                task->taskAgeCycles = 1 + ((currentTimeUs - task->lastSignaledAt) / task->desiredPeriod);
                task->dynamicPriority = 1 + task->staticPriority * task->taskAgeCycles;
                waitingTasks++;
            } 
            else if (task->checkFunc(currentTimeBeforeCheckFuncCall, currentTimeBeforeCheckFuncCall - task->lastExecutedAt))
            {
#if defined(SCHEDULER_DEBUG)
                DEBUG_SET(DEBUG_SCHEDULER, 3, micros() - currentTimeBeforeCheckFuncCall);
#endif
#ifndef SKIP_TASK_STATISTICS
                if (calculateTaskStatistics) 
                {
                    const uint32_t checkFuncExecutionTime = micros() - currentTimeBeforeCheckFuncCall;
                    checkFuncMovingSumExecutionTime += checkFuncExecutionTime - checkFuncMovingSumExecutionTime / MOVING_SUM_COUNT;
                    checkFuncTotalExecutionTime += checkFuncExecutionTime;   // time consumed by scheduler + task
                    checkFuncMaxExecutionTime = MAX(checkFuncMaxExecutionTime, checkFuncExecutionTime);
                }
#endif
                task->lastSignaledAt = currentTimeBeforeCheckFuncCall;
                task->taskAgeCycles = 1;
                task->dynamicPriority = 1 + task->staticPriority;
                waitingTasks++;
            } else 
            {
                task->taskAgeCycles = 0;
            }
        }
        else 
        {
            // Task is time-driven, dynamicPriority is last execution age (measured in desiredPeriods)
            // Task age is calculated from last execution
            task->taskAgeCycles = ((currentTimeUs - task->lastExecutedAt) / task->desiredPeriod);
            if (task->taskAgeCycles > 0) {
                task->dynamicPriority = 1 + task->staticPriority * task->taskAgeCycles;
                waitingTasks++;
            }
        }

        if (task->dynamicPriority > selectedTaskDynamicPriority) {
            const bool taskCanBeChosenForScheduling =
                (outsideRealtimeGuardInterval) ||
                (task->taskAgeCycles > 1) ||
                (task->staticPriority == TASK_PRIORITY_REALTIME);
            if (taskCanBeChosenForScheduling) {
                selectedTaskDynamicPriority = task->dynamicPriority;
                selectedTask = task;
            }
        }
    }

    totalWaitingTasksSamples++;
    totalWaitingTasks += waitingTasks;

    currentTask = selectedTask;

    if (selectedTask) 
    {
        // Found a task that should be run
        selectedTask->taskLatestDeltaTime = currentTimeUs - selectedTask->lastExecutedAt;
        selectedTask->lastExecutedAt = currentTimeUs;
        selectedTask->dynamicPriority = 0;

        // Execute task
#ifdef SKIP_TASK_STATISTICS
        selectedTask->taskFunc(currentTimeUs);
#else
        if (calculateTaskStatistics) 
        {
            const timeUs_t currentTimeBeforeTaskCall = micros();
            selectedTask->taskFunc(currentTimeBeforeTaskCall);
            const timeUs_t taskExecutionTime = micros() - currentTimeBeforeTaskCall;
            selectedTask->movingSumExecutionTime += taskExecutionTime - selectedTask->movingSumExecutionTime / MOVING_SUM_COUNT;
            selectedTask->totalExecutionTime += taskExecutionTime;   // time consumed by scheduler + task
            selectedTask->maxExecutionTime = MAX(selectedTask->maxExecutionTime, taskExecutionTime);
        } else {
            selectedTask->taskFunc(currentTimeUs);
        }

#endif
#if defined(SCHEDULER_DEBUG)
        DEBUG_SET(DEBUG_SCHEDULER, 2, micros() - currentTimeUs - taskExecutionTime); // time spent in scheduler
    } else {
        DEBUG_SET(DEBUG_SCHEDULER, 2, micros() - currentTimeUs);
#endif
    }

    GET_SCHEDULER_LOCALS();
}

CleanFlight 源码分析 一，任务调度

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CleanFlight 源码分析一，任务调度