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    SubjectRe: [RFC 00/15] x86_64: Optimize percpu accesses
    Christoph Lameter wrote:
    >> The nice thing about the non-zero-based scheme i386 uses is that setting
    >> gs-base to zero means that percpu variables accesses get directly to the
    >> prototype percpu data area, which simplifies boot time setup (which is
    >> doubly awkward on 32-bit because you need to generate a GDT entry rather
    >> than just load an MSR as you do in 64-bit).
    > Great but it causes trouble in other ways as discussed.

    What other trouble? It works fine.

    > Its best to consistently access
    > per cpu variables using the segment registers.

    It is, but initially the segment base is 0, so just using a percpu
    variable does something sensible from the start with no special setup.


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      Last update: 2008-07-10 19:55    [W:0.019 / U:70.100 seconds]
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