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    SubjectRe: [PATCH 0/7] [RFC] hugetlb: pagetable_operations API (V2)
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    On Mon, 2007-03-19 at 13:05 -0700, Adam Litke wrote:
    > For the common case (vma->pagetable_ops == NULL), we do almost the
    > same thing as the current code: load and test. The third instruction
    > is different in that we jump for the common case instead of jumping in
    > the hugetlb case. I don't think this is a big deal though. If it is,
    > would an unlikely() macro fix it?

    I wouldn't worry about micro-optimizing it at that level. The CPU does
    enough stuff under the covers that I wouldn't worry about it at all.

    I wonder if the real differential impact (if any) is likely to come from
    the pagetable_ops cacheline being hot or cold, since it is in a
    different place in the structure than the flags. But, from a quick
    glance I see a few vm_ops references preceding pagetable_ops references,
    so the pagetable_ops cacheline might already be hot most of the time.

    BTW, are there any other possible users for these things other than
    large pages?

    -- Dave

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