[time-nuts] Designing an embedded precision GPS time

Denny Page denny at cococafe.com
Sun Nov 12 13:46:18 EST 2017

The 6-7us of latency in this discussion does not involve the network path. In this regard network latency is fairly well addressed with hardware timestamping, although trying to get readings across the clock domains looses dozens of nanos of precision. In this discussion, the 6-7us of latency originates from servicing the serial device interrupt in order to timestamp the TOS pulse. This is entirely in the kernel, and there is no user space context switch involved. If you have a way to dramatically reduce the 6-7us interrupt latency with the Linux kernel, say to a 100 nanos, please do share.

> On Nov 12, 2017, at 07:23, Attila Kinali <attila at kinali.ch> wrote:
> The kernel has already quite a few low-latency network paths.
> You just need to enable them and then cut out the biggest timing uncertainty:
> the user-space to kernel context switch.

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