From: Thomas Gleixner <tglx@linutronix.de>
To: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Vincent Guittot <vincent.guittot@linaro.org>,
lkml <linux-kernel@vger.kernel.org>,
linux-hotplug@vger.kernel.org,
Frederic Weisbecker <fweisbec@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
amit.kucheria@linaro.org, Rusty Russell <rusty@rustcorp.com.au>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH V5 2/2] tracing, perf : add cpu hotplug trace events
Date: Thu, 24 Feb 2011 20:49:51 +0000 [thread overview]
Message-ID: <alpine.LFD.2.00.1102242148400.2701@localhost6.localdomain6> (raw)
In-Reply-To: <alpine.LFD.2.00.1102241536120.31831@xanadu.home>
On Thu, 24 Feb 2011, Nicolas Pitre wrote:
> On Thu, 24 Feb 2011, Peter Zijlstra wrote:
>
> > On Thu, 2011-02-24 at 15:24 -0500, Nicolas Pitre wrote:
> >
> > > Most SMP ARM processors are going to use it soon. Powering down idle
> > > cores provides substantial power saving.
> >
> > And why can't regular idle paths be used? CPU hotplug is a massively
> > expensive operation.
>
> The idle path assumes that the CPU state is preserved. We're talking
> about cores completely going down with power pulled beneath them and
> eventually rebooted dynamically here.
That's the equivalent of physical hotplug, but we still have all the
memory state around, so it is possible from idle, when we have the
full isolation features in place.
Thanks,
tglx
next prev parent reply other threads:[~2011-02-24 20:49 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-24 17:33 [PATCH V5 2/2] tracing, perf : add cpu hotplug trace events Vincent Guittot
2011-02-24 18:40 ` Thomas Gleixner
2011-02-28 13:36 ` Vincent Guittot
2011-03-02 10:08 ` Thomas Gleixner
2011-03-02 19:02 ` Vincent Guittot
2011-03-02 21:12 ` Thomas Gleixner
2011-02-24 18:46 ` Peter Zijlstra
2011-02-24 20:11 ` Alan Cox
2011-02-24 20:16 ` Thomas Gleixner
2011-02-24 20:24 ` Nicolas Pitre
2011-02-24 20:30 ` Peter Zijlstra
2011-02-24 20:40 ` Alan Cox
2011-02-24 20:40 ` Nicolas Pitre
2011-02-24 20:49 ` Peter Zijlstra
2011-02-24 20:49 ` Thomas Gleixner [this message]
2011-02-24 21:04 ` Alan Cox
2011-02-24 21:12 ` Thomas Gleixner
2011-02-24 21:17 ` Peter Zijlstra
2011-02-24 21:33 ` Thomas Gleixner
2011-02-24 20:47 ` Thomas Gleixner
2011-02-24 20:58 ` Peter Zijlstra
2011-02-24 21:03 ` Thomas Gleixner
2011-02-24 21:11 ` Paul E. McKenney
2011-02-24 20:27 ` Peter Zijlstra
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