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    SubjectRe: [PATCH v2 32/36] x86/entry: Micro-optimize compat fast syscall arg fetch

    * Andy Lutomirski <luto@kernel.org> wrote:

    > we're following a 32-bit pointer, and the uaccess code isn't smart
    > enough to figure out that the access_ok check isn't needed.
    >
    > This saves about three cycles on a cache-hot fast syscall.

    Another request: could you please stick the benchmarking code of the various x86
    system call variants into 'perf bench' - under tools/perf/bench/, so that
    measurements can be done on more hardware and can be reproduced easily?

    I'd suggest we dedicate an entirely new benchmark family to it: 'perf bench x86'
    and then have:

    perf bench x86 syscall vdso
    perf bench x86 syscall int80
    perf bench x86 syscall vdso-compat

    or so?

    ( I have some perf bench cleanups in -tip, so if you do this please base it on top
    of that. )

    Thanks,

    Ingo


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