[ntp:questions] Linux 2.6 and clock frequency

shane-dated-1173632795.f2b9df at cm.nu shane-dated-1173632795.f2b9df at cm.nu
Fri Feb 9 17:14:35 UTC 2007

Hey all,

I've been experimenting with Linux kernel settings with respect to how they
affect ntpd as I understand for the gps18lvc to work effectively, one needs
a fairly accurate clock.  One thing I've found is with hz=100, I'm getting
an ntp.drift of around 40 but with a fairly good rootdispersion at stratum 2
of approx 15.  With hz=250, the frequency drift drops to 15 but dispersion
and jitter rise.  Finally, I tried the high-res timers patch with and
without dynamic ticks.  The hr-timers have frequency at 0.039but the jitter
reported by ntpq -p on peers is still higher than a vanilla kernel with

So my question is should the drift be varying so much based on kernel hz and
why would there be increased jitter with a reduced frequency error?  Has
anyone else tried the hrtimers patch and had good results?


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