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Date: Thu, 24 Feb 2011 20:11:24 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>, 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>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH V5 2/2] tracing, perf : add cpu hotplug trace events
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> Anybody who is interested in the latency of cpu hotplug is deluding
> himself, also cpu hotplug is _NOT_ a power management feature, so the
> rest of your justification just disappeared as well.

Actually CPU hotplug is a power management feature on some devices where
you need to shutdown one of the cores to enter low power modes.
Remember we use it as part of the suspend paths and various processors
nowdays drop into a suspend to RAM type state on CPU idling.

Alan