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    SubjectRe: [PATCH v3 21/26] arm64: Introduce asm/vdso/arch_timer.h
    On Fri, Mar 13, 2020 at 03:43:40PM +0000, Vincenzo Frascino wrote:
    > The vDSO library should only include the necessary headers required for
    > a userspace library (UAPI and a minimal set of kernel headers). To make
    > this possible it is necessary to isolate from the kernel headers the
    > common parts that are strictly necessary to build the library.
    >
    > Introduce asm/vdso/arch_timer.h to contain all the arm64 specific
    > code. This allows to replace the second isb() in __arch_get_hw_counter()
    > with a fake dependent stack read of the counter which improves the vdso
    > library peformances of ~4.5%. Below the results of vdsotest [1] ran for
    > 100 iterations.

    The subject seems to imply a non-functional change but as you read, it
    gets a lot more complicated. Could you keep the functional change
    separate from the header clean-up, maybe submit it as an independent
    patch? And it shouldn't go in without Will's ack ;).

    --
    Catalin

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