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Date: Sat, 12 Apr 2008 15:11:22 +0200
From: Jan Kiszka <jan.kiszka@domain.hid>
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Subject: Re: [Xenomai-help] rt_task_sleep_until question
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To: Klaas Gadeyne <klaas.gadeyne@domain.hid>
Cc: xenomai@xenomai.org

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Klaas Gadeyne wrote:
> Hi,
>=20
> 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.
>=20
> 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.
>=20
>  head /tmp/app.txt
> current_time =3D 1207928393295939429
> sleep until 18446744073709551615
> [TIMERLOOP] Total errors =3D 1, return code =3D -110
> current_time =3D 1207928393296000379
> sleep until 18446744073709551615
> [TIMERLOOP] Total errors =3D 2, return code =3D -110
> current_time =3D 1207928393296005409
> sleep until 18446744073709551615
> [TIMERLOOP] Total errors =3D 3, return code =3D -110
> current_time =3D 1207928393296009604
>=20
> What did I overlook here?

Probably an overflow issue: (RTIME)~0 will be converted to TSCs, and if=20
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=20
timeout date (in TSC units) before the current date -> ETIMEDOUT. Can=20
you confirm this?

Jan


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