Re: setting system clock-rate

["David Lord" <netbsd%lordynet.org@localhost>]

On 1 Mar 2009 at 13:47, Kristoff Bonne wrote:

> Hi All,
> 
> 
> I have installed netbsd 4.0.1 on an old PC (pentium III, 1 Ghz).
> 
> 
> Due to some reason (probably hardware I guess), the system-clock runs
> about 3 % to fast. The RTV-clock is correct, but the system-clock goes 1
> to 2 seconds more in advance every minute.
> 
> The time-difference is that large, that ntpd is unable to sync.
> 

On NetBSD-3 I have compiled kernels with "options TIMER_FREQ=nnnnnnn"
with nnnnnnn adjusted from default so that ntpd frequency offset
settles down to < 10ppm. Some of the systems have needed 500ppm 
frequency adjustment then ntpd doesn't have a problem.

I'm not sure this works with NetBSD-4 as it is supposed to self 
calibrate and seems to have it right on some of upgrades I've done
but others are left at such a large offset that ntpd struggles
to sync and limited to short polling intervals. I'm in process of
move to 5.0 and will eventually give the TIMER_FREQ a try with 
the worst behaving pcs.


David


> 
> 
> Using debian and "adjtimex", I managed to get the "tick" and
> "frequency"-values to correct this:
> tick: 9738, frequency: -1503002
> 
> So, how do I configure netbsd to change the system clock-rate. "sysctl
> -w kern.clockrate=9738" doesn't work as that value seams to be read-only.
> 
> 
> I tried using ntp with copying the value in the driftfile to netbsd
> (-22.934), but that doesn't work neither. (doesn't ntpd use that value
> to set the system-clock rate?)
> 
> 
> Anybody any idea?
> 
> 
> 
> Cheerio! Kr. Bonne.
> 
> -- 
> jabber/gtalk: kristoff%krbonne.net@localhost
> 
>