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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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