[ntp:questions] SO_TIMESTAMPING experiments (sub-us jitter over LAN)
gsricalde at gmail.com
Thu Oct 18 11:43:02 UTC 2012
On Thursday, October 18, 2012 6:40:01 PM UTC+8, Miroslav Lichvar wrote:
> NTP supports interleaved mode in peer associations which does the
> timestamp followup. It would be really nice if ntpd supported the
> SO_TIMESTAMPING option.
Days of lurking Dr. Mills' site and I didn't notice that.
> You may want to try nohz=off, it seems there is a bug in the kernel
> which can cause an extra jitter of couple microseconds in the
> system clock readings when the system is idle.
Must be the reason why one of my Atom machines needs a process looping
a 10 ms sleep to bring the PPS jitter down.
> > 91509 509
> > 89577 -991
> > 88365 -795
> > 89574 -731
> > 90593 -163
> > 89360 -1067
> > 92650 -318
> > 90634 -910
> > 89455 -989
> > 89511 -1080
> > 88874 -693
> > 88534 -1140
> Cool. Are those numbers nanoseconds?
Original post is wrong, those are nanoseconds.
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