On Friday 03 October 2008 22:48:32 Christoph Lameter wrote:
quoted text
> Andrew Morton wrote:
> > But I'd have though that it would be possible to only allocate the
> > storage for online CPUs.  That would be a pretty significant win for
> > some system configurations?
>
> We  have tried that but currently the kernel (core and in particular arch
> code) keeps state for all possible cpus in percpu segments. Would require
> more extensive cleanup of numerous arches to do.

It shouldn't be a big win, since possible ~= online for most systems.  And 
having all the per-cpu users register online and offline cpu callbacks is 
error prone and a PITA.

Rusty.
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