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    SubjectRe: [PATCH] x86-64: espfix for 64-bit mode *PROTOTYPE*
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    I wanted to avoid the "another cpu made this allocation, now I have to free" crap, but I also didn't want to grab the lock if there was no work needed.

    On April 21, 2014 6:06:19 PM PDT, Andrew Lutomirski <amluto@gmail.com> wrote:
    >On Mon, Apr 21, 2014 at 5:53 PM, H. Peter Anvin <hpa@zytor.com> wrote:
    >> Well, if 2^17 CPUs are allocated we might 2K pages allocated. We
    >could easily do a bitmap here, of course. NR_CPUS/64 is a small
    >number, and would reduce the code complexity.
    >>
    >
    >Even simpler: just get rid of the check entirely. That is, break out
    >of the higher level loops once one of them is set (this should be a
    >big speedup regardless) and don't allocate the page if the first PTE
    >is already pointing at something.
    >
    >After all, espfix_already_there is mostly a duplicate of
    >init_espfix_cpu.
    >
    >--Andy

    --
    Sent from my mobile phone. Please pardon brevity and lack of formatting.


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