linux-kernel - Re: RFC for a new Scheduling policy/class in the Linux-kernel

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Message-ID: <4A5B61DF.8090101@nortel.com>
Date:	Mon, 13 Jul 2009 10:33:35 -0600
From:	"Chris Friesen" <cfriesen@...tel.com>
To:	Raistlin <raistlin@...ux.it>
CC:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Douglas Niehaus <niehaus@...c.ku.edu>,
	Henrik Austad <henrik@...tad.us>,
	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Bill Huey <billh@...ppy.monkey.org>,
	Linux RT <linux-rt-users@...r.kernel.org>,
	Fabio Checconi <fabio@...dalf.sssup.it>,
	"James H. Anderson" <anderson@...unc.edu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ted Baker <baker@...fsu.edu>,
	Dhaval Giani <dhaval.giani@...il.com>,
	Noah Watkins <jayhawk@....ucsc.edu>,
	KUSP Google Group <kusp@...glegroups.com>,
	Tommaso Cucinotta <cucinotta@...up.it>,
	Giuseppe Lipari <lipari@...is.sssup.it>
Subject: Re: RFC for a new Scheduling policy/class in the Linux-kernel

Raistlin wrote:

> Very basically: from the analysis point of view one easy and effective
> solution would be to have the blocked-running tasks --i.e., the tasks
> blocked on some lock that have been left on the rq to proxy-execute the
> lock owner-- busy waiting while the lock owner is running. This allows
> for retaining a lot of nice properties BWI already has, as far as
> analyzability is concerned.
> 
> On the other hand, from the practical end efficiency point of view, it
> would be not that difficult to block these otherwise-spinning tasks, in
> order to avoid wasting CPU time too much... The only important thing is
> to properly account the budget of the correct server/group (which
> probably must be the otherwise-spinning task's one), or the analysis is
> gone again! :-O

Could you elaborate on this "proper accounting"?

If task A is blocked waiting for a lock (held by a task B on another
cpu) and we run task C instead, how would you propose that the
accounting be handled?

Chris
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