[ntp:questions] Re: setting CONFIG_HZ=2000 makes ntpd go crazy

David L. Mills mills at udel.edu
Fri Feb 17 00:38:55 UTC 2006


I don't think so, and there's a way to prove it. The issue is how the 
adjtime() routine handles clock adjustments. That syscall should 
amortize the adjustment in microseconds at a 500-PPM rate. I bet it 
doesn't. And, should the precision time kernel modifications are active, 
it will go absolutely bonkers unless some parameters are carefully 
recalculated. There should be enough detail in the code commentary for a 
kernelmonger to do that.

As all modern machinery I touch here has a processor cycle counter of 
some form or another, for good timekeeping you don't need to up the Hz. 
Only if you need better than 10-ms precision in order to produce an 
external event at a given time.



Harlan Stenn wrote:

> You are probably losing clock interrupts like crazy at HZ=2000.
> H

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