Re: [Xenomai-help] Application broken 2.3.4 ---> 2.4.0

["Ignacio García Pérez" <iggarpe@domain.hid>]

Ignacio García Pérez escribió:

Ok, replying myself with further findings:

It turns out that the following code miserably fails to set the thread 
periodic:

rt_task_set_periodic(&_blink_thread, rt_timer_read(), mili2count(250));

Where this actually works:

rt_task_set_periodic(&_blink_thread, TM_NOW, mili2count(250));

Which makes me think that rt_task_set_periodic() fails when the passed 
idate is in the past.

And you may say: why the hell do you use rt_timer_read() when you can 
use TM_NOW ???

Well, I think that rt_task_set_periodic should word (AND DID) both ways, 
but actually I have a very good reason to (sometimes) use an idate in 
the past: I want the blinking synchronized to the "event" as closely as 
possible. If there is a delay D from my recorded time for the event to 
the actual call to rt_task_set_periodic, I can:

a) Use rt_task_set_periodic(TM_NOD)

b) Use rt_task_set_periodic(recorded_time)

In the first case there will be a delay of D from every period to the 
"event", while in the second case that delay will be only in the FIRST 
execution of the periodic task.

Anyway, something is truly screwed up when 
rt_task_set_periodic(&_blink_thread, rt_timer_read(), mili2count(250)) 
fails to make the task periodic...

> Hi,
>
> I've compiled a previously 100% working application under the new 2.4.0 
> release and found the following issues:
>
>
> 1- rt_task_set_periodic does not work sometimes?
>
> In this application I have a periodic task (250ms period) which is used 
> to blink some lights. The blinking is occasionally resynchronized to 
> some external event, and this is what I do:
>
> In the periodic task:
>
> blink_count = 0;
> rt_task_set_periodic();
> for (;;) {
>     whatever();
>     blink_count = (blink_count + 1) & 3;
>     rt_task_wait_period();
> }
>
> Some somewhere else, when I want to synchronize the blinking:
>
>     blink_count = 0;
>     rt_task_set_periodic();
>
> This has worked perfectly until version 2.4.0. It seems that further 
> calls to rt_task_set_periodic (from a different task) break the 
> periodicity (the periodic task enters rt_task_wait_period() and never 
> leaves again).
>
> Any clues?
>