[ntp:questions] Setting the maximum rate of change

Spoon root at localhost.invalid
Sun Mar 25 18:48:44 UTC 2007

Rune Magnussen wrote:

> Spoon wrote:
>> I had randomly thought it might be a good idea to crank HZ up to 250.
>> Are you saying ntpd will break if I set HZ to 250 in Linux 2.6?
> The (PPS?) kernel discipline only works with 100 HZ. That is a kernel
> issue. I am using 250 HZ on my ntp client PC and it works fine. If the
> clock lags behind and ntpd cannot correct that then there is a problem and
> it could be lost interrupts. With high HZ-values like 1000 lost interrupts
> are more likely.

I am confused.

kernel/time/ntp.c defines int do_adjtimex(struct timex *txc)
which contains the following comment:

/* PPS is not implemented, so these are zero */


On a related note, there seems to be an effort to make the NTP
kernel code independent of HZ.



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