Time keeping Issues with the low-resolution TSC timecounter

[Jung-uk Kim]

On Wednesday 15 June 2011 03:27 pm, Ian FREISLICH wrote:
> > > The problem I noticed first is that it takes unusually long
> > > until a key press is repeated. With the default eventtimer
> > > (HPET) it seems to take about 4s, which can be slightly
> > > improved by switching to i8254.
> > >
> > > The "error beep" seems to take longer than usual, too,
> > > and the system "feels sluggish" in general.
> > >
> > > An effect that is easier to measure is that the system is
> > > unable to properly keep the time. Again the problem is less
> > > severe when using i8254 instead of HPET:
> >
> > [SNIP]
> >
> > First of all, please do not mix timecounter issues with
> > eventtimer. They are not directly related.
> >
> > Can you please show me verbose boot messages *without* your
> > patch? Does "sysctl kern.timecounter.hardware=HPET" help
> > *without* touching eventtimers?
>
> I have the same issue with my system (Atom N270).  The effect that
> I see is about 29 wall clock seconds are recorded as 1 system
> second.

Can please you send me output from the following?

sh -c 'count=10; while [ $count -gt 0 ]; do count=$((count - 1));\
sysctl kern.timecounter; sleep 1; done'

> I had do something similar to the OP to make my system useable since
> it doesn't seem possible to influence timecounter choice at boot
> time. 

You can just add the following line in /etc/sysctl.conf for now:

kern.timecounter.hardware=HPET

Jung-uk Kim