Subject: Re: Proposed changes to cc_microset().
To: Alan Barrett <>
From: Nathan J. Williams <>
List: tech-kern
Date: 07/08/2004 10:46:46
Alan Barrett <> writes:

> While you are changing things in this area, it would be nice if you also
> added a way for cc_microtime and friends to be informed of deliberate
> changes in CPU speed (such as the i386 "Enhanced SpeedStep" stuff in
> sys/arch/i386/i386/est.c).

Is it worthwhile? The fallout from not doing it is just inaccurate
sub-second time estimates until the next cycle-count calibration
(currently once a second, and here being proposed to be about ten
seconds). In any case the calibrator needs a full calibration period
at the new speed before it can do things correctly, so such an update
call could only reset the calibration timer, saving 1/2 of a
calibration period.

	- Nathan