Dave Hart wrote: > On Feb 5, 9:33 pm, Terje Mathisen <"terje.mathisen at tmsw.no"> wrote: >> Dave Hart wrote: >>> Looking at the last 800 loopstats lines for the refclock, representing >>> a bit more than 3 hours of 16s polls, the offsets in microseconds look >>> like >>> -79.497 min >>> -26.961 mean >>> 20.565 max >>> 17.381 stddev >>> The jitter (us) >>> 1.907 min >>> 7.974 mean >>> 35.64 max >>> 4.651 stddev >>> How does that look to more jaded PPS eyes? >> Pretty bad actually: After a day or so you should see 0-5 us offset and >> jitter. > > I hope, but I'm not optimistic. This is PPS on Windows without kernel > support, so the timestamp comes after the OS has noticed the state > change of the CD line and passed that news along to ntpd. A spot > check of recent peerstats lines looks consistent with the stats above. > >>> The refclock is a Garmin GPS 18x LVC connected to a dual PII 400 via >> I have one of those! (A Dell?) > > Yes, PowerEdge 2300. It uses 9G and 18G drives on a SCSI RAID > controller. A whole gig of RAM ;) I had a dual-400 410 workstation > as well, it's been long retired. > >> It might work even better in single-cpu mode if it is a dedicated ntp >> server. > > It's running with a patch to lock the main and timer threads to the > 2nd CPU using SetThreadAffinity. I haven't tried locking the async I/ > O thread as well, but I will now. It's also running with a patch to > the interpolation code which is more selective about baseline counter/ > time pairs it uses. There is a faster server on the same LAN I could > try as well, but I figured slower is better for understanding how bad > the user-mode PPS implementation is. >
You only set the thread affinity if it really needs it otherwise it doesn't really matter which CPU it's using. Certainly the I/O thread should not be set. Danny > Cheers, > Dave Hart > > _______________________________________________ > questions mailing list > [email protected] > https://lists.ntp.org/mailman/listinfo/questions > > _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
