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    SubjectRe: [PATCH 09/11] pps: low level IRQ timestamps recording.
    On 12/02/2009 09:18 AM, Rodolfo Giometti wrote:
    > Add low level IRQ timestamps recording for x86 (32 and 64 bits)
    > platforms and enable UART clients in order to use it.
    > This improves PPS precision. :)

    It also invokes getnstimeofday on every single interrupt, including ones
    which have absolutely nothing to do with the PPS, and are potentially
    high volume. getnstimeofday can be a fairly expensive operation,
    especially if the best available clock is away from the CPU, or it
    requires extensive arithmetic in order to normalize the clock value...


    H. Peter Anvin, Intel Open Source Technology Center
    I work for Intel. I don't speak on their behalf.

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