Message-ID: <4CE18C7E.2060202@unitn.it>
Date: Mon, 15 Nov 2010 20:39:42 +0100
From: Luca Abeni <luca.abeni@unitn.it>
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To: "James H. Anderson" <anderson@cs.unc.edu>
CC: Raistlin <raistlin@linux.it>, Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
        Steven Rostedt <rostedt@goodmis.org>,
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        Frederic Weisbecker <fweisbec@gmail.com>,
        Darren Hart <darren@dvhart.com>, Johan Eker <johan.eker@ericsson.com>,
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        Claudio Scordino <claudio@evidence.eu.com>,
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        Fabio Checconi <fabio@gandalf.sssup.it>,
        Tommaso Cucinotta <cucinotta@sssup.it>,
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        Nicola Manica <nicola.manica@disi.unitn.it>,
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        paulmck <paulmck@linux.vnet.ibm.com>,
        Bjoern Brandenburg <bbb@email.unc.edu>
Subject: Re: [RFC][PATCH 18/22] sched: add reclaiming logic to -deadline tasks
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On 15/11/10 19:37, James H. Anderson wrote:
[...]
> If you're talking about our most recent "stochastic" paper, it is about
> supporting
> soft real-time task systems on a multiprocessor where resource
> reservations are
> used. The main result of the paper is that if you provision the
> reservation for a
> task slightly higher than it's average-case execution time
[...]
BTW, I think we are aligned on this.

I was a little bit surprised when Peter mentioned allocating a runtime 
equal to the average execution time (because of the meta-stability 
considerations that Tommaso also mentioned), but I fully agree that if 
the allocated runtime is higher than the average execution time then the 
queue is stable and it's possible to find a bound for the expected 
tardiness (or even its probability distribution... This is similar to my 
"probabilistic deadlines").


			Luca
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