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

Chase Venters
2006-06-16T21:19:20Z

(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