Port-arm archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: TS-7200: time sync issues

In message: <200812100329.mBA3TPUr000226%ginger.cmf.nrl.navy.mil@localhost>
            Ken Hornstein <kenh%cmf.nrl.navy.mil@localhost> writes:
: >You should never see more than one of these messages, and that at
: >startup.  Once it does the initial slew of the phase since it has
: >estimated the proper frequency, the system clock should be running
: >within a few ppm of the reference system.
: >
: >The problem is that NTP's algorithm assumes that the initial clock
: >frequency error on the system is within ~128ppm of the reference
: >system.
: I'm sorry if this wasn't clear ... but the problem seems to be within
: the settimeofday() (or perhaps clock_settime()) function.  Once ntpd
: gets "lucky" and gets the clock within 128ms, it's happy.  Right now
: my TS-7200 box has been up for over a day without any time steps, and
: ntptime shows a frequency of -51 ppm.

Why must this be the case? ntpd doesn't even use these functions.

You'd get the same problem if your frequency was wrong, or if you were
missing clock interrupts so that time would run slow.

What happens if you do two ntpdates in a row?


Home | Main Index | Thread Index | Old Index