RTEMS tasks timesliced instead of running to completion. TIMESLICE flag is not active!

[Joel Sherrill]

On Thu, Apr 30, 2020, 10:14 AM Fernando Domínguez Pousa <fdpousa at gmv.com>
wrote:

> Hello,
>
>
>
> I am executing a program which executes four different task with testing
> operations. These tasks were created and launched in this way:
>
>
>
> status = rtems_task_create(Task_name[i], (rtems_task_priority) 2,
> RTEMS_MINIMUM_STACK_SIZE, RTEMS_DEFAULT_MODES,
>
>             (i%2) == 0 ? RTEMS_FLOATING_POINT : RTEMS_DEFAULT_ATTRIBUTES,
> &Task_id[i]);
>
>
>
> status = rtems_task_start(Task_id[i], (i%2) == 0 ? Task1_EntryPoint :
> Task2_EntryPoint, i);
>
>
>
> As you can see all task are created with the same priority, and launched
> one after the other inside a for loop. They are configured in default
> modes, so time slicing is disabled by default  (all mode bits are 0). This
> result would be expected due to each task would run-to-completion because
> all tasks have the same priority:
>
>
>
> The expected result:
>
> [MAIN] Waiting for testing tasks to complete...
>
> [TASK 0] Starting...
>
> [TASK 0] Computed the correct floating point result.
>
> [TASK 1] Starting...
>
> [TASK 1] Computed the correct integer result.
>
> [TASK 2] Starting...
>
> [TASK 2] Computed the correct floating point result.
>
> [TASK 3] Starting...
>
> [TASK 3] Computed the correct integer result.
>
> [MAIN] All testing tasks completed.
>
>
>
> Nevertheless, using RTEMS_DEFAULT_MODES, RTEMS_DEFAULT_MODES |
> RTEMS_TIMESLICE or RTEMS_DEFAULT_MODES | RTEMS_NO_PREEMPT either as
> rtems_mode, the result is always the same.
>
>
>
> The actual result:
>
> [MAIN] Waiting for testing tasks to complete...
>
> [TASK 0] Starting...
>
> [TASK 1] Starting...
>
> [TASK 2] Starting...
>
> [TASK 3] Starting...
>
> [TASK 0] Computed the correct floating point result.
>
> [TASK 1] Computed the correct integer result.
>
> [TASK 2] Computed the correct floating point result.
>
> [TASK 3] Computed the correct integer result.
>
> [MAIN] All testing tasks completed.
>
>
>
> At RTEMS API Guide:
>
>
>
> The timeslicing component is used by the RTEMS scheduler to determine how
> the processor is allocated to tasks of equal priority. If timeslicing is
> enabled (RTEMS_TIMESLICE), then RTEMS will limit the amount of time the
> task can execute before the processor is allocated to another ready task of
> equal priority.
>
>
>
> *The length of the timeslice is application dependent and specified in the
> Configuration Table. If timeslicing is disabled (**RTEMS_NO_TIMESLICE**),
> then the task will be allowed to execute until a task of higher priority is
> made ready. *However I have not any task with higher priority, Init task
> priority is lower.
>
>
>
> If RTEMS_NO_PREEMPT is selected, then the timeslicing component is
> ignored by the scheduler.
>
>
>
> How can I execute this tasks in a run to completion fashion for same
> priority tasks? Task 0 starts and ends, then Task1 starts and ends… etc,
>

There are many things that could be happening. Can you post the program?

>
>
> Regards,
>
>
>
> Fer.
>
>
>
> P Please consider the environment before printing this e-mail.
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