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Subject: Re: [RFC patch 1/2] sched: dynamically adapt granularity with
 nr_running
From: Mike Galbraith <efault@gmx.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>, Tony Lindgren <tony@atomide.com>
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Date: Mon, 13 Sep 2010 12:06:18 +0200
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On Mon, 2010-09-13 at 11:55 +0200, Peter Zijlstra wrote:
> On Mon, 2010-09-13 at 11:50 +0200, Mike Galbraith wrote:
> > Perhaps lag should be negated if you've received a
> > reasonable chunk or something.. but what we really want is a service
> > deadline.
> 
> Hey, I've got a patch for that too :-)
> 
> Not rebased to anything current, but should be able to get frobbed onto
> the last zero-lag thingy without too much grief (I think).

A frobbing I shall go.

> +/*
> + * Entity is eligible once it received less service than it ought to have,
> + * eg. lag >= 0.
> + *
> + * lag_i = S_i - s_i = w_i*(V - w_i)
> + *
> + * lag_i >=0 -> V >= v_i
> + *
> + *     \Sum (v_i - v)*w_i
> + * V = ------------------ + v
> + *          \Sum w_i
> + *
> + * lag_i >= 0 -> \Sum (v_i - v)*w_i >= (v_i - v)*(\Sum w_i)
> + */

Ew, more of that icky stuff.

	-Mike