Re: PATCH - update TSC freq when cpufreq changes it

On Tuesday 27 February 2007 23:16, Nate Lawson wrote:
> Attached is a patch that uses eventhandlers to update the TSC freq.
> This is important because DELAY() uses TSC directly (on i386 and amd64)
> but the rate calculated at boot changes if cpufreq is in use.
>
> It maintains current behavior that cpufreq transitions are denied if
> TSC is the active timecounter.  The API is that there is a pre and post
> transition eventhandler that is called by the cpufreq core.  The pre
> handler is passed the next state (including freq, power, etc.) and can
> store a non-zero status value in the output arg to indicate it wants to
> reject the transition.  The post handler also is passed the next state
> and the result of the transition (0 on success).

Any reason for passing the result to the post handler in by reference - 
other than being able to re-use the same function type as in the pre 
handler?  API-wise this seems to be a mistake as one consumer could mess 
up the result for the rest and the variable name "error" in the INVOKE 
also suggests that this could be used to report back.

> Once any issues are addressed, I'll update this for amd64, ALTQ, and
> possibly PC98.  Non-x86 archs can stick with the current behavior if
> they're satisfied or hook the eventhandlers provided to DTRT.

-- 
/"\  Best regards,                      | mlaier_at_freebsd.org
\ /  Max Laier                          | ICQ #67774661
 X   http://pf4freebsd.love2party.net/  | mlaier_at_EFnet
/ \  ASCII Ribbon Campaign              | Against HTML Mail and News