Subject: Re: HEADS UP: timecounters (branch simonb-timecounters) merged into
To: Frank Kardel <>
From: Steven M. Bellovin <>
List: current-users
Date: 06/09/2006 08:55:13
On Fri, 09 Jun 2006 13:34:42 +0200, Frank Kardel <> wrote:

> >
> Yes, this is something I expected to happen.
> Background: The implementation of TSC is
> different for different CPUs. Older CPUs use the clock
> frequency to drive TSC and are thus dependent on selected
> frequency. Newer CPUs are said to count at a fixed frequency
> regardless of the selected frequency (possibly using bigger
> increments).
> FreeBSD did disable TSC when some kind of Powermanagement
> is detected.
> Instead of TSC try using i8254:
>      sysctl  -w kern.timecounter.hardware=i8254

Is it safe to put that into /etc/sysctl.conf unconditionally?  I use estd,
which changes the frequency quite frequently when I'm running on battery.

		--Steven M. Bellovin,