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From: Ingo Molnar <mingo@elte.hu>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Chuck Ebbert <cebbert@redhat.com>,
	linux-kernel@vger.kernel.org,
	Arjan van de Ven <arjan@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Li Zefan <lizf@cn.fujitsu.com>
Subject: Re: [patch x86/core] x86: allow number of additional hotplug CPUs to be set at compile time, V2
Date: Thu, 2 Oct 2008 21:50:48 +0200	[thread overview]
Message-ID: <20081002195048.GA12109@elte.hu> (raw)
In-Reply-To: <48E525A1.5080509@zytor.com>


* H. Peter Anvin <hpa@zytor.com> wrote:

> Ingo Molnar wrote:
>>>
>>> The default number of additional CPU IDs for hotplugging is 
>>> determined by asking ACPI or mptables how many "disabled" CPUs there 
>>> are in the system, but many systems get this wrong so that e.g. a 
>>> uniprocessor machine gets an extra CPU allocated and never switches 
>>> to single CPU mode.
>>>
>>> And sometimes CPU hotplugging is enabled only for suspend/hibernate  
>>> anyway, so the additional CPU IDs are not wanted. Allow the number to 
>>> be set to zero at compile time.
>>>
>
> Wouldn't this be better to have a runtime option?

yeah - and we already have the additional_cpus=x boot option, but a boot 
option is not generally useful to a distribution.

	Ingo

  reply	other threads:[~2008-10-02 19:51 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-01 23:19 [patch x86/core] x86: allow number of additional hotplug CPUs to be set at compile time Chuck Ebbert
2008-10-02  8:12 ` Ingo Molnar
2008-10-02 19:30   ` [patch x86/core] x86: allow number of additional hotplug CPUs to be set at compile time, V2 Chuck Ebbert
2008-10-02 19:42     ` Ingo Molnar
2008-10-02 19:48       ` H. Peter Anvin
2008-10-02 19:50         ` Ingo Molnar [this message]
2008-10-02  9:12 ` [patch x86/core] x86: allow number of additional hotplug CPUs to be set at compile time Andi Kleen
2008-10-02 19:25   ` Chuck Ebbert
2008-10-02 19:44     ` Andi Kleen
2008-10-02 20:09       ` Chuck Ebbert
2008-10-02 20:40         ` Andi Kleen
2008-10-04 16:52           ` <PING> " Andi Kleen
2008-10-04 22:30             ` Chuck Ebbert
2008-10-05 10:28               ` Ingo Molnar
2008-10-05 14:52                 ` Thomas Gleixner
2008-10-05 15:20                   ` Ingo Molnar
2008-10-05 15:51                     ` Thomas Gleixner
2008-10-05 15:56                       ` Ingo Molnar
2008-10-05 20:39                       ` Andi Kleen
2008-10-05 21:49                         ` Thomas Gleixner
2008-10-05 22:45                           ` Andi Kleen
2008-10-05 20:28                     ` Andi Kleen

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