linux-kernel - Re: [QUERY]: Is using CPU hotplug right for isolating CPUs?

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Message-ID: <20140115113406.GC31570@twins.programming.kicks-ass.net>
Date:	Wed, 15 Jan 2014 12:34:06 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Frédéric Weisbecker <fweisbec@...il.com>,
	Kevin Hilman <khilman@...aro.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Amit Kucheria <amit.kucheria@...aro.org>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
	Linaro Networking <linaro-networking@...aro.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [QUERY]: Is using CPU hotplug right for isolating CPUs?

On Wed, Jan 15, 2014 at 04:17:26PM +0530, Viresh Kumar wrote:
> On 15 January 2014 16:08, Peter Zijlstra <peterz@...radead.org> wrote:
> > Nah, its just ugly and we should fix it. You need to be careful to not
> > place tasks in a cpuset you're going to unplug though, that'll give
> > funny results.
> 
> Okay. So how do you suggest to get rid of cases like a work queued
> on CPU1 initially and because it gets queued again from its work handler,
> it stays on the same CPU forever.

We should have a cpuset.quiesce control or something that moves all
timers out.

> And then there were timer overflow events that occur because hrtimer
> is started by tick-sched stuff for 450 seconds later in time.

-ENOPARSE
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