[ltp] Massive clock drift on new thinkpad R32

[Tod Harter]

On Friday 22 November 2002 02:16 am, David Peterson wrote:
> Hi Todd,
>
> When I think of changes I have made, only a couple of things readily
> come to mind:
>
> - upgraded from 2.4.18 kernel to 2.4.19 kernel using the debian kernel
> images
> - installed a sound driver (the i810_audio module, which also loads the
> soundcore module and ac97_codec module)
>
> As you can see from the following post, the system is "losing time"
>
Well, theoretically either of those changes might be involved. Technicall=
y=20
what happens is that once Linux kernel is up and running it reads the RTC=
 to=20
find out what time it is and sets the 'system time'. From then on every 1=
0=20
milliseconds or so the timer chip should assert a 'clock-tick' interrupt,=
 at=20
which point the kernel updates system time. If there is a hardware or=20
software problem with that interrupt then naturally it would cause the=20
kernel's concept of time to drift. Anything running in 'ring 0' (kernel o=
r=20
most device drivers) could easily be the culprit in missed clock-ticks, i=
ts=20
just that GENERALLY the consequences of such problems rapidly become=20
catastrophic, so such a bug is rare to find in a production release of an=
y=20
kind.=20

Given the steps you say you've taken to correct the problem I'm not sure =
what=20
other advice I'd have for you. It is always possible its a hardware probl=
em=20
and XP simply manages to run OK by sheer chance (slightly different way i=
t=20
accesses hardware, etc.). It kind of feels like one of those (reinstall f=
rom=20
scratch and hope it goes away) kind of problems (I know, I sound like MS =
tech=20
support, ah well).

--=20
Tod G. Harter
Giant Electronic Brain