Re: FOR REVIEW: New x86-64 vsyscall vgetcpu()

[Chase Venters]

(Sorry for the empty reply! Pine over a laggy SSH connection is annoying 
sometimes)

On Fri, 16 Jun 2006, Andi Kleen wrote:

> > To this last point, it might be more reasonable to map in a page that
> > contained a new structure with a stable ABI, which mirrored some of
> > the task_struct information, and likely other useful information as
> > needs are identified in the future.  In any case, it would be hard
> > to beat a single memory read for performance.
>
> That would mean making the context switch and possibly other
> things slower.

Well, if every process had a page of its own, what would the context 
switch overhead be?

But, I'm not advocating exporting anything. Though I sort of like the 
vgetcpu() idea because I was working on a user-space slab allocator 
recently and magazines could use vgetcpu() instead of pthread keys.
(Also means if threads > cpus I'd get better results).

Thanks,
Chase
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