questions about time delay in the while(1) block of a task

[Anonymous]

I tested the time delay functions in the while(1) block of a task. But I found some strange results that are hard to understand. The test are presented as follows:

Environment : WICED6.1+CYW94307+ThreadX

I created two tasks,i.e. task1 and task2, with the same or different priorities. The code of each task is as follows:

void thread1_main( uint32_t arg )

{

    uint32_t temp = arg ;

    while ( 1 )

    {

        printf( "This thread 111111\r\n" ) ;

        wiced_rtos_delay_milliseconds( 1 ) ;

    }

    WICED_END_OF_CURRENT_THREAD( ) ;

}

The results are pasted here:

priority set	delay time(in ms)	result
task1 : 7 , task2 : 7	1 or longer	both tasks can run correctly
task1 : 7 , task2 : 8	1	only task1 can run correctly
task1 : 7 , task2 : 8	2 or longer	both tasks can run correctly

So, my first question is:

1、When the priorities are set different, why only task1 run correctly when the delay time is 1ms , but both tasks run when the delay time is longer?

Another question is:

2、When I replace wiced_rtos_delay_milliseconds(1) with wiced_rtos_delay_microseconds(1000) or even wiced_rtos_delay_microseconds(1000000) , only the task with higher priority run. Why does not the wiced_rtos_delay_microseconds() function cause task scheduling？

[ShengY_96 · Accepted solution]

Q1、When the priorities are set different, why only task1 run correctly when the delay time is 1ms , but both tasks run when the delay time is longer?

A: Seems the reason is: The execute time of code: printf( "This thread 111111\r\n" ) ; Plus the thread switch time is longer than 1ms and less than 2ms. So the situation: task1: 7, task2:8, delay(1ms)'s switch logic is: Switch to Task1->Printf("This thread 1111111\r\n")-> Suspend Task1-1ms->Switch to Task 2->Printf("This thread 22222\r\n"); but this is not execute completely（Like only print "T"）as the Task1 is triggered after 1ms-> Switch to Task 1-> Printf("This thread 1111111\r\n"). Try to use this printf("1\n\r"); or larger the delay time.

Q2. When I replace wiced_rtos_delay_milliseconds(1) with wiced_rtos_delay_microseconds(1000) or even wiced_rtos_delay_microseconds(1000000) , only the task with higher priority run. Why does not the wiced_rtos_delay_microseconds() function cause task scheduling？

A: wiced_rtos_delay_miliseconds include the tx_thread_sleep which can set the task to suspend but wiced_rtos_delay_microseconds had not include the tx_thread_sleep. Say: the wiced_rtos_delay_microseconds only include the delay function not include the RTOS suspend function.

Regards

Jenson

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