Re: CPU attachent and detachment in a running Linux system

[ferret@phonewave.net]

On Mon, 18 Dec 2000 Heiko.Carstens@de.ibm.com wrote:

> Hi,
> 
> >> I still wonder what you and other people think about the idea of an
> >> interface where the parts of the kernel with per-cpu dependencies should
> >> register two functions...
> >Why not compile kernel with structeres big enough for 32 processors,
> >and then just add CPUs up to the limit without changing anything?
> 
> That's a good point and it would probably work for attachment of cpus, but
> it won't work for detachment because there are some data structures that
> need to be updated if a cpu gets detached. For example it would be nice
> to flush the per-cpu cache of the detached cpu in the slabcache. Then one
> has to think of pending tasklets for the detached cpu which should be
> moved to another cpu and then there are a lot of per-cpu data structures
> in the networking part of the kernel.. most of them seem to be for
> statistics only but I think these structures should be updated in any
> case.
> So at least for detaching it would make sense to register functions which
> will be called whenever a cpu gets detached.


Plus userspace CPU monitors will need to know when the CPU arrangement has
changed.

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