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From: "Luck, Tony" <tony.luck@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>, "Yu, Fenghua" <fenghua.yu@intel.com>
CC: Ingo Molnar <mingo@elte.hu>, H Peter Anvin <hpa@zytor.com>,
        "Siddha, Suresh B" <suresh.b.siddha@intel.com>,
        "Mallick, Asit K" <asit.k.mallick@intel.com>,
        Arjan Dan De Ven <arjan@linux.intel.com>,
        linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
        linux-pm <linux-pm@vger.kernel.org>,
        "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Rusty Russell <rusty@rustcorp.com.au>
Subject: RE: [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or
 nmi
Thread-Topic: [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or
 nmi
Thread-Index: AQHNQoAPFj9sktPv9UGlpY91mwdZJJbrDNOA//+Lt1A=
Date: Mon, 4 Jun 2012 20:18:42 +0000
Message-ID: <3908561D78D1C84285E8C5FCA982C28F192F7F17@ORSMSX104.amr.corp.intel.com>
References: <1338833876-29721-1-git-send-email-fenghua.yu@intel.com>
 <alpine.LFD.2.02.1206042203590.3086@ionos>
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> I'm working on a proper state machine driven online/offline sequence,
> where you can put the cpu into an intermediate state which avoids
> bringing it down completely. This is enough to get the full
> powersaving benefits w/o having to go through all the synchronization
> states of a full online/offline. That will shorten the onlining time
> of an previously offlined cpu to almost nothing.

Will this also be a step towards Fenghua's goal of being able to
take cpu#0 away. I.e. will your state machine be fully symmetric
and allow for cpu#0 to enter this intermediate mostly-offline state?

-Tony
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