From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: 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>,
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>,
Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or nmi
Date: Mon, 04 Jun 2012 22:33:21 +0200 [thread overview]
Message-ID: <1338842001.28282.135.camel@twins> (raw)
In-Reply-To: <alpine.LFD.2.02.1206042203590.3086@ionos>
On Mon, 2012-06-04 at 22:11 +0200, Thomas Gleixner wrote:
> I understand what you are trying to do, though I completely disagree
> with the solution.
>
> The main problem of the current hotplug code is that it is an all or
> nothing approach. You have to tear down the whole thing completely
> instead of just taking it out of the usable set of cpus.
>
> 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.
>
> I really want to avoid adding more bandaids to the hotplug code before
> we have sorted out the existing horror.
Its far worse.. you shouldn't _ever_ care about hotplug latency unless
you've got absolutely braindead hardware. We all now ARM has been
particularly creative here, but is Intel now trying to trump ARM at
stupid?
next prev parent reply other threads:[~2012-06-04 20:33 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 [this message]
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
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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