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