Time keeping Issues with the low-resolution TSC timecounter

Ian FREISLICH ianf at clue.co.za
Wed Jun 15 19:53:29 UTC 2011

> > 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.
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


Ian Freislich

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