linux-kernel - Re: On migrate_disable() and latencies

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Date:	Fri, 22 Jul 2011 16:57:43 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	linux-rt-users <linux-rt-users@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>, Carsten Emde <ce@...g.ch>,
	Clark Williams <williams@...hat.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Kumar Gala <galak@...e.crashing.org>,
	Ralf Baechle <ralf@...ux-mips.org>,
	rostedt <rostedt@...dmis.org>
Subject: Re: On migrate_disable() and latencies

On Fri, 2011-07-22 at 12:49 +0200, Peter Zijlstra wrote:
> > The scenario is on where you stack N migrate-disable tasks on a run
> > queue (necessarily of increasing priority). Doing this requires all cpus
> > in the system to be as busy, for otherwise the task would simply be
> > moved to another cpu.
> 
> This implies it requires at least nr-cpus^2 tasks to pull this off. 

OK, scrap that, 2*nr-cpus is enough.
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