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    SubjectRe: [RFC PATCH v2 05/10] lib: vdso: inline do_hres()
    On Mon, Dec 23, 2019 at 6:31 AM Christophe Leroy
    <christophe.leroy@c-s.fr> wrote:
    >
    > do_hres() is called from several places, so GCC doesn't inline
    > it at first.
    >
    > do_hres() takes a struct __kernel_timespec * parameter for
    > passing the result. In the 32 bits case, this parameter corresponds
    > to a local var in the caller. In order to provide a pointer
    > to this structure, the caller has to put it in its stack and
    > do_hres() has to write the result in the stack. This is suboptimal,
    > especially on RISC processor like powerpc.
    >
    > By making GCC inline the function, the struct __kernel_timespec
    > remains a local var using registers, avoiding the need to write and
    > read stack.
    >
    > The improvement is significant on powerpc.

    I'm okay with it, mainly because I don't expect many workloads to have
    more than one copy of the code hot at the same time.

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