linux-kernel - Re: [RFC][PATCH] sched: avoid huge bonus to sleepers on busy machines

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Message-Id: <1262609358.9734.52.camel@marge.simson.net>
Date:	Mon, 04 Jan 2010 13:49:18 +0100
From:	Mike Galbraith <efault@....de>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Suresh Jayaraman <sjayaraman@...e.de>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] sched: avoid huge bonus to sleepers on busy
 machines

On Mon, 2010-01-04 at 13:36 +0100, Peter Zijlstra wrote:
> On Mon, 2010-01-04 at 13:30 +0100, Mike Galbraith wrote:
> > Any diddling of sleeper fairness would have to be accompanied with a
> > preemption model change methinks. 
> 
> Just told jays the exact same thing on IRC ;-)
> 
> Also, workloads are interesting, the signal test thing is the easiest to
> test the preemption side, various things like QPID show the down-side
> iirc.

Best testcase for the downside in my arsenal is vmark.  It performs a
_lot_ better with no wakeup preemption.  'Course if you run your box
that way, you quickly find out what a horrible idea that is :)

	-Mike

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