Time keeping Issues with the low-resolution TSC timecounter

Jung-uk Kim jkim at FreeBSD.org
Mon Jun 13 18:56:57 UTC 2011

On Monday 13 June 2011 12:44 pm, Fabian Keil wrote:
> I'm experiencing time-related issues that seem to be caused by
> the low-resolution TSC timecounter (r222866).
> 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:


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 

Jung-uk Kim

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