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