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Subject: Re: [RFC 8/12][PATCH] SCHED_DEADLINE: wait next instance syscall
 added.
From: Raistlin <raistlin@linux.it>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
       michael trimarchi <michael@evidence.eu.com>,
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On Mon, 2009-12-28 at 15:30 +0100, Peter Zijlstra wrote:
> > However, for SCHED_DEADLINE tasks, it should be the call with which eac=
h
> > job closes its current instance. In fact, in this case, the task is put=
 to
> > sleep and, when it wakes up, the scheduler is informed that a new job
> > arrived, saving the overhead that usually comes with a task activation
> > to enforce maximum task bandwidth.
>=20
> The changelog suggests (and a very brief looks seems to confirm) that
> this code could be much smaller by using hrtimer_nanosleep().
>=20
> The implementation as presented seems to only call ->wait_interval()
> when the timer arms, which seems like a bug, we should always call it,
> regardless of whether we're on a period boundary.
>=20
Ok, thanks, I'll look carefully at that! The current code is an attempt
of mine to replicate the behaviour of clock_nanosleep, but you're
definitely right here, it can be done much better.

Thanks and regards,
Dario

--=20
<<This happens because I choose it to happen!>> (Raistlin Majere)
----------------------------------------------------------------------
Dario Faggioli, ReTiS Lab, Scuola Superiore Sant'Anna, Pisa  (Italy)

http://blog.linux.it/raistlin / raistlin@ekiga.net /
dario.faggioli@jabber.org

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