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    SubjectRe: [tip:x86/mm] x86/mm: Avoid superflous leave_mm() in the TLB flush path
    On Mon, Dec 5, 2011 at 9:56 AM, tip-bot for Shaohua Li
    <shaohua.li@intel.com> wrote:
    >
    > x86/mm: Avoid superflous leave_mm() in the TLB flush path
    >
    > If just one page VA tlb is required to be flushed and current
    > task is in lazy TLB state, doing leave_mm() is superfluous
    > because it flushes the whole TLB.  This can reduce some TLB
    > miss.

    Are you sure this is a good idea?

    We may be *much* better off leaving the VM and avoiding future IPI's
    than trying to flush pages one by one over and over again.

    IPI's are expensive.

    I don't think you thought this through, and if you *did* think it
    through and actually have numbers that it's cheaper to stay with the
    MM, I think you need to show those numbers.

    Linus
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