Re: [Xenomai-help] Preemptive scheduling

["Jack Whorn" <jackwhorn@domain.hid>]

Hi Gilles,

> Once your program enters this infinte loop, it never gets out, so :
> - your assumption that "t_task_set_mode periodically clears T_LOCK and
>   T_SHIELD and sets T_RRB" is false;

Yeah, I just realized that it does this only once. According to http://snail.fsffrance.org/www.xenomai.org/documentation/branches/v2.0.x/html/api/group__task.html#ga44But I think that the arguments used in the rt_task_set_mode() -call are correct. Isn't that sufficient for the Linux OS to catch e.g. keyboard interrupts?

> - even if higher priority task runs, Linux, which is Xenomai idle task
>   never runs, so the system locks up.

Gotcha, that sounds sensible to me.

Actually, the higher-priority task uses some linux-system calls to store data to hard disk. This does no longer take place as soon as the infinite loop is entered. I expected priority coupling to solve that. Where is my error in reasoning?

> In short, maybe you have observed some scheduling problems, but your
> example does not demonstrate them. Such misuse of Xenomai should be
> caught by the watchdog, if you enable it.

I might try that watchdog, thanks for this hint!

Regards,

Jack
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