From: Arjan van de Ven <arjan@linux.intel.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Fenghua Yu <fenghua.yu@intel.com>, Ingo Molnar <mingo@elte.hu>,
H Peter Anvin <hpa@zytor.com>,
Suresh B Siddha <suresh.b.siddha@intel.com>,
Tony Luck <tony.luck@intel.com>,
Asit K Mallick <asit.k.mallick@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>
Subject: Re: [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or nmi
Date: Tue, 05 Jun 2012 08:27:06 -0700 [thread overview]
Message-ID: <4FCE254A.6050504@linux.intel.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1206051014540.1542-100000@iolanthe.rowland.org>
On 6/5/2012 7:17 AM, Alan Stern wrote:
> On Mon, 4 Jun 2012, Arjan van de Ven wrote:
>
>>> I disagree. Deactivating a cpu for power saving is halfway to hotplug
>>> anyway. I'd rather unify the two cases, where we can specify how dead a
>>> CPU should be, than have individual archs and boards do random hacks.
>>
>> well on PC's there really is no difference at least;
>> idle equals "all power removed" already there.
>
> This doesn't sound right at all. Len Brown has often told us that on
> Intel chips, power can't be removed from a package until _all_ the
> cores in the package are idle.
but "cpu hotplug" does not change that.. in fact, cpu hotplug is
implemented as a C state...
and to be specific; power will get removed from the cores one at a time.
you just cannot remove the power from the memory controller until the
last one is off.
next prev parent reply other threads:[~2012-06-05 15:27 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-04 18:17 [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or nmi Fenghua Yu
2012-06-04 18:17 ` [PATCH 1/6] x86/Documentation/kernel-parameters.txt: Add wakeup_cpu_via_init kernel parameter help Fenghua Yu
2012-06-04 18:17 ` [PATCH 2/6] x86/head_32.S/head_64.S: Kernel entry code after waking up offline CPU via mwait or nmi Fenghua Yu
2012-06-04 18:17 ` [PATCH 3/6] x86/smpboot.c: Wake " Fenghua Yu
2012-06-04 18:58 ` Suresh Siddha
2012-06-04 19:35 ` Yu, Fenghua
2012-06-04 18:17 ` [PATCH 4/6] x86/apic_flat_64.c: Wakeup function in apic calls mwait or nmi method Fenghua Yu
2012-06-04 18:17 ` [PATCH 5/6] x86/x2apic_cluster.c: Wakeup function in x2apic_cluster " Fenghua Yu
2012-06-04 18:17 ` [PATCH 6/6] x86/x2apic_phys.c: Wakeup function in x2apic_phys " Fenghua Yu
2012-06-04 18:17 ` Fenghua Yu
2012-06-04 20:11 ` [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or nmi Thomas Gleixner
2012-06-04 20:18 ` Luck, Tony
2012-06-04 22:52 ` Thomas Gleixner
2012-06-04 20:33 ` Peter Zijlstra
2012-06-05 0:40 ` Rusty Russell
2012-06-05 1:23 ` Arjan van de Ven
2012-06-05 7:38 ` Peter Zijlstra
2012-06-05 14:17 ` Alan Stern
2012-06-05 15:27 ` Arjan van de Ven [this message]
2012-06-05 7:39 ` Peter Zijlstra
2012-06-05 16:02 ` Yu, Fenghua
2012-06-05 16:09 ` Peter Zijlstra
2012-06-05 16:18 ` Yu, Fenghua
2012-06-05 16:19 ` Peter Zijlstra
2012-06-05 17:44 ` Luck, Tony
2012-06-05 17:50 ` Peter Zijlstra
2012-06-05 19:43 ` Thomas Gleixner
2012-06-05 19:45 ` Peter Zijlstra
2012-06-05 19:49 ` Peter Zijlstra
2012-06-05 19:51 ` Arjan van de Ven
2012-06-05 19:52 ` Peter Zijlstra
2012-06-05 20:47 ` Thomas Gleixner
2012-06-05 21:30 ` Peter Zijlstra
2012-06-05 22:09 ` Thomas Gleixner
2012-06-06 8:23 ` Peter Zijlstra
2012-06-06 8:30 ` Peter Zijlstra
2012-06-06 8:40 ` Peter Zijlstra
2012-06-05 22:12 ` Paul E. McKenney
2012-06-06 8:40 ` Peter Zijlstra
2012-06-06 8:42 ` Peter Zijlstra
2012-06-06 14:44 ` Paul E. McKenney
2012-06-06 15:46 ` Peter Zijlstra
2012-06-06 23:20 ` Paul E. McKenney
2012-06-08 9:20 ` Peter Zijlstra
2012-06-06 8:43 ` Peter Zijlstra
2012-06-06 14:41 ` Paul E. McKenney
2012-06-06 15:23 ` Arjan van de Ven
2012-06-06 15:48 ` Peter Zijlstra
2012-06-06 15:49 ` Paul E. McKenney
2012-06-06 16:59 ` Arjan van de Ven
2012-06-05 21:29 ` Paul E. McKenney
2012-06-05 21:37 ` Peter Zijlstra
2012-06-05 22:00 ` Paul E. McKenney
2012-06-06 12:17 ` Peter Zijlstra
2012-06-06 14:43 ` Paul E. McKenney
2012-06-05 19:51 ` Peter Zijlstra
2012-06-05 20:58 ` Andi Kleen
2012-06-05 21:15 ` Thomas Gleixner
2012-06-05 21:33 ` Thomas Gleixner
2012-06-05 23:13 ` Andi Kleen
2012-06-06 1:52 ` Arjan van de Ven
2012-06-05 18:07 ` Peter Zijlstra
2012-06-05 19:54 ` Luck, Tony
2012-06-05 19:56 ` Peter Zijlstra
2012-06-05 9:36 ` Thomas Gleixner
2012-06-05 13:41 ` [PATCH] kthread: Implement park/unpark facility Thomas Gleixner
2012-06-05 14:01 ` Peter Zijlstra
2012-06-05 14:05 ` Peter Zijlstra
2012-06-07 0:04 ` H. Peter Anvin
2012-06-10 5:40 ` Rusty Russell
2012-06-11 9:26 ` Thomas Gleixner
2012-06-12 0:23 ` Rusty Russell
2012-06-05 15:35 ` [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or nmi Jiang Liu
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