Re: [chrony-users] GPS / Chrony NTP server config questions

[Denny Page <dennypage@xxxxxx>]

Interrupt latency for character devices in Linux is 6-7 us, even with no other activity. You can get better than this using a gpio and spinning on it, but I haven’t seen anyone do this with with serial pps.

Denny

On Nov 16, 2017, at 09:57, Bill Unruh <unruh@xxxxxxxxxxxxxx> wrote:

The PPS accuracy is largely determined by the interrupt handling time, which
is something like a usec. It depends, so that if the the pps comes in when the
computer is reading a disk (which used non-interruptable interrupts) it will
be delayed by many microseconds.