Hi Andrew,
> Thanks for the report and patch. I would be interested to see the output from
> an "NTPTime_Report 1" command gives on that system, with or without your fix,
> since that report displays the measured tick rate as well as the nominal one
> and your report implies the two were significantly different.
This is the output of NTPTime_Report
NTP driver is synchronized with server
Syncronization interval = 60.0 seconds
Last synchronized at 2008-12-05 10:10:28.001558
OS tick rate = 50 Hz (nominal)
Measured tick rate = 50.002 Hz
> I did wonder whether the NTP time provider should correct for problems caused
> by an incorrect clock tick rate since it is able to detect them, but I was
> persuaded by Eric Norum not to do so.
The measured tick rate is pretty close to the nominal tick rate and it took
several hours until the ticksToSkip-counter had accumulated enough ticks to
halt the IOC-Time for about 2 seconds. I consider this as a "normal"
incorrect clock tick rate.
Btw. The problem didn't occur, if running the EPICS example application on the
same hardware. I had to use a real-world application (reading Keitley-devices
via GPIB and doing average calculations). But then I was able to reproduce
it on another IOC with similar hardware.
I believe, as long as the jitter of the osdNTPGet-call was big enough to return
a time value every now and then, which didn't need to skip a tick, the IOC-time
was adjusted and the problem did not occur.
Regards
Jens
- References:
- NTP-Time on RTEMS(vxWorks) Problem Jens Eden
- Re: NTP-Time on RTEMS(vxWorks) Problem Andrew Johnson
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