Re: [PATCH] Correct nr_processes() when CPUs have been unplugged

From: Paul E. McKenney
Date: Wed Nov 04 2009 - 14:44:33 EST

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
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