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Date: Wed, 21 Apr 2010 22:38:36 +0200
Message-ID: <s2tc5b2c05b1004211338y814bc3b2o547a6eecdf64ca7f@mail.gmail.com>
Subject: Re: Considerations on sched APIs under RT patch
From: Primiano Tucci <p.tucci@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: rostedt@goodmis.org, linux-kernel@vger.kernel.org,
       tglx <tglx@linutronix.de>
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> No, any syscall can end up blocking/scheduling there are no exceptions.
> But blocking doesn't mean its non-deterministic, esp. when coupled with
> things like PI.
>
> But you do have to treat system resources as such, that is they can (and
> will) create cross-cpu dependencies, if you do not take that into
> account you will of course be surprised.
>
I actually don't understand why do you recall PI so frequently, it
seems to be the unique point of interest.
Actually I take care about not sharing cross-cpu resources, but I
cannot take care of what the kernel should do.
In my viewpoint is unacceptable that the scheduler apis can led into a
rescheduling.
It voids any form of process control.
If I lose the control while controlling other processes, Quis
custodiet ipsos custodes?

P.S. It actually does not happen in other RTOSes, e.g., VxWorks SMP

Primiano,

--
 Primiano Tucci
 http://www.primianotucci.com
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