Re: [Xenomai-help] rt_task_sleep_until question

[Jan Kiszka <jan.kiszka@domain.hid>]

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Klaas Gadeyne wrote:
> Hi,
> 
> I've noticed that threads which, in my ignorant opinion, are supposed
> to be sleeping, get woken up much earlier than I expect them to be.
> 
> Please find attached a modified version of the trivial-periodic.c
> application, which creates a RT_TASK that should sleep as long as
> possible (i.e. until unblocked by a signal handler).  However, the
> task gets woken up much earlier (and many times) _before_ that time it
> seems.
> 
>  head /tmp/app.txt
> current_time = 1207928393295939429
> sleep until 18446744073709551615
> [TIMERLOOP] Total errors = 1, return code = -110
> current_time = 1207928393296000379
> sleep until 18446744073709551615
> [TIMERLOOP] Total errors = 2, return code = -110
> current_time = 1207928393296005409
> sleep until 18446744073709551615
> [TIMERLOOP] Total errors = 3, return code = -110
> current_time = 1207928393296009604
> 
> What did I overlook here?

Probably an overflow issue: (RTIME)~0 will be converted to TSCs, and if 
your box runs at > 1GHZ, the result of this conversion will by something 
< (RTIME)~0 due to the overflow. And this can result in an absolute 
timeout date (in TSC units) before the current date -> ETIMEDOUT. Can 
you confirm this?

Jan


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