Thanks for the explanations Miroslav. I guess I was just trying to illustrate that it is indeed possible to get sub-ms behaviour on VMs providing you have a good source of NTP.
> On 8/01/2019, at 10:31 PM, Miroslav Lichvar <[email protected]> wrote: > > In the estimate of the maximum error, it's important to include also > half of the root delay, so in your examples it would be about 250 > microseconds. OK - still less than 1ms as required by the OP. Maybe this maximum error estimate could also be shown in 'chronyc tracking'? > > Raspberry PIs have ethernet on USB, which adds some latency, and IIRC > the default interrupt coalescing is very large. You might want to try > setting a smaller rx-usecs value with ethtool -C, which should reduce > the root delay and give the clients a better estimate of the maximum > error. I had a quick look at this, but the nic in the RPi doesn't seem to support the coalesce options of ethtool with Debian Stretch. As you say there may be better h/ware for the job, but the RPi/Uputronics combo is an inexpensive, and also well documented, way of getting very good timekeeping on a small LAN. B -- Bryan Christianson [email protected] -- To unsubscribe email [email protected] with "unsubscribe" in the subject. For help email [email protected] with "help" in the subject. Trouble? Email [email protected].
