RES: RES: testing multitasking rtems

Wendell Pereira da Silva wendell.silva at
Wed Sep 19 16:45:19 UTC 2012

OK, Luca.

Try to adjust your tasks as the following pseudo-code and see what happens.
Let know if you have more doubts.


  volatile bool quit = false;

  printk("task 1 exiting...\n");

      printf("hello world!\n");
  printk("task 2 exiting...\n");

  int i = 0;


  while(i < 120) // Let tasks run for aprox 2 minutes.

  quit = true; // Let the tasks delete themselfs
  printk("Task init: end of test\n");
  rtems_task_delete(rtems_task_self()); // Say "Addio, mondo crudele."

De: Luca Cinquepalmi [mailto:cinquepalmi at]
Enviada em: quarta-feira, 19 de setembro de 2012 13:24
Para: Wendell Pereira da Silva
Cc: rtems-users at
Assunto: Re: RES: testing multitasking rtems

Wendell, thank you for your answer... I try to explain better:
- task1 makes a led blinking (in a while cycle)
- task2 print a simple "hello world"

I want "hello world" to be printed while led is blinking. How can I share CPU with these two tasks?
Shall I delete task at the end? Shall I define a semaphore?
I tried to modify task priority but it has no effects...
Even if led blinking (task 1) start, task 2 doesn't...

Hope now it's clearer...


Il 19/09/2012 17.18, Wendell Pereira da Silva ha scritto:

Unless you have two CPUs (or a dual core CPU) and SMP support for your BSP, it's impossible to get two tasks running at the same time (if I understood what you mean "... a second task running when one is still running).
In most cases, on single core (or single processor) BSP's tasks share the same CPU being droved by any scheduling policy implemented in the RTOS.

If you want your tasks sharing the CPU, please, check the tasks priority, attributes and execution mode.

Probably task one has higher priority than task two, and task one never blocks.

A good reference is the RTEMS Users Guide<>, topic 5.2.

Hope it helps.


De: rtems-users-bounces at<mailto:rtems-users-bounces at> [mailto:rtems-users-bounces at] Em nome de Luca Cinquepalmi
Enviada em: quarta-feira, 19 de setembro de 2012 11:16
Para: Joel Sherrill
Cc: rtems-users at<mailto:rtems-users at>
Assunto: Re: testing multitasking rtems

How can I run Two tasks in the same time? Evey task ends with delete_task so the next task starts
when the previous is finished. How can I make a second task running when task one is still running?


rtems_task Init(rtems_task_argument ignored)


I want that task 2 starts while task1 is still running? How can I do this?
Thank you


Il 18/09/2012 13.12, Joel Sherrill ha scritto:
On 09/18/2012 06:07 AM, Luca Cinquepalmi wrote:

Hi all,
is there on line or in rtems documentaion any exmaple (c source code) of
how testing multitasking?
Nearly every test is multitasking. All are if you consider there is
at least an application task/thread and an idle task.

The most basic tests for a BSP are hello and ticker. Ticker has
3 user tasks which run at different intervals.

I'm not able to find any suggestion. Thank you

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