linux-kernel - Re: periods and deadlines in SCHED

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Message-Id: <21AA2C13-8831-47A2-9464-28E84DBD72B0@email.unc.edu>
Date:	Sun, 11 Jul 2010 08:46:12 +0200
From:	Bjoern Brandenburg <bbb@...il.unc.edu>
To:	Raistlin <raistlin@...ux.it>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Song Yuan <song.yuan@...csson.com>,
	Dmitry Adamushko <dmitry.adamushko@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Nicola Manica <nicola.manica@...i.unitn.it>,
	Luca Abeni <lucabe72@...il.it>,
	Claudio Scordino <claudio@...dence.eu.com>,
	Harald Gustafsson <harald.gustafsson@...csson.com>,
	bastoni@...unc.edu, Giuseppe Lipari <lipari@...is.sssup.it>
Subject: Re: periods and deadlines in SCHED_DEADLINE


On Jul 10, 2010, at 9:08 AM, Raistlin wrote:

>> 
>> As a side note, almost all global EDF hard real-time admission tests can handle tasks with constrained deadlines transparently. However, as far as I can tell, they do not apply to SCHED_DEADLINE.
>> 
> This is the only part I am not sure I got... Can you explain me what do
> you mena by "they do not apply" ?

I was under the impression that the kernel implementation is a P-EDF implementation. Now it seems to me that it is in fact a "P-EDF with frequent migrations" implementation. I'd be hesitant to just assume that it "approximates G-EDF" sufficiently well to apply any of the published G-EDF tests.

- Björn

---
Björn B. Brandenburg
Ph.D. Student 
Dept. of Computer Science
University of North Carolina at Chapel Hill
http://www.cs.unc.edu/~bbb




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