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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>,
	Ian Campbell <Ian.Campbell@citrix.com>, Tejun Heo <tj@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Rusty Russell <rusty@rustcorp.com.au>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Correct nr_processes() when CPUs have been unplugged
Date: Wed, 4 Nov 2009 11:44:20 -0800	[thread overview]
Message-ID: <20091104194420.GG6736@linux.vnet.ibm.com> (raw)
In-Reply-To: <alpine.DEB.1.10.0911041434530.7409@V090114053VZO-1>

On Wed, Nov 04, 2009 at 02:37:06PM -0500, Christoph Lameter wrote:
> On Tue, 3 Nov 2009, Paul E. McKenney wrote:
> 
> > > Cpu hotplug is rarely used (what you listed are rare and unusual cases)
> > > and therefore online cpus == possible cpus == present cpus.
> >
> > Though it is not unusual for "possible cpus" to be quite a bit larger
> > than "online cpus"...
> 
> The only reason for possible cpus to be larger than online cpus is if you
> can actually plugin more processors while the system is running. Typically
> the larger possible cpus seems to be some sort of Vendor BIOS screwup
> where the vendor advertises how many processors the maximum configuration
> of a certain type of hardware would suppport if one would buy that config.

Or if you are running as a guest OS on top of some sort of hypervisor.

							Thanx, Paul

  reply	other threads:[~2009-11-04 19:44 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-11-03 10:11 [PATCH] Correct nr_processes() when CPUs have been unplugged Ian Campbell
2009-11-03 15:51 ` Linus Torvalds
2009-11-03 16:07 ` Ingo Molnar
2009-11-03 18:34   ` Christoph Lameter
2009-11-04  6:09     ` Paul E. McKenney
2009-11-04 19:37       ` Christoph Lameter
2009-11-04 19:44         ` Paul E. McKenney [this message]
2009-11-04 10:42     ` Ingo Molnar
2009-11-05  0:43     ` Rusty Russell
2009-11-04 11:10   ` Ian Campbell
2009-11-04  8:34 ` Rusty Russell

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