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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...

    -hpa


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



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