ACPI-fast default timecounter, but HPET 83% faster

[Bruce Cran]

On Thu, 30 Apr 2009 08:46:41 -0400
John Baldwin <jhb at freebsd.org> wrote:

> On Sunday 26 April 2009 10:27:42 pm Garrett Cooper wrote:

> > Why's the default ACPI-fast? For power-saving functionality or
> > because of the `quality' factor? What is the criteria that
> > determines the `quality' of a clock as what's being reported above
> > (I know what determines the quality of a clock visually from a
> > oscilloscope =])?
> 
> I suspect that the quality of the HPET driver is lower simply because
> no one had measured it previously and HPET is newer and less "proven".
> 

http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/dev/acpica/acpi_hpet.c
shows some of the history behind the decision.  Apparently it used to
be slower but it was hoped it would get faster as systems supported it
better. I guess that's happening now.

-- 
Bruce Cran