RFC: powerd patch to review related to bin/104689

[Nate Lawson]

Matteo Riondato wrote:
> All,
> while digging in the PR database, I found bin/104689 and decided to
> implement the idea in it.
> 
> Basically, I added support in powerd(8) to specify a maximum and a
> minimum frequencies for adaptive mode. That is, powerd will only
> switch between frequencies between the specified bounds instead of
> switching through all available frequencies.
> 
> I think the idea is nice and I hope to have implemented it in the
> right way, but I'd like your review before committing it.
> 
> Patch is attached, or can be found at
> http://people.freebsd.org/~matteo/powerd-minmaxfreq.patch
> 
> (leave me in the reply list, since I'm not subscribed to
> freebsd-acpi@)
> 
> Thanks in advance
> Best regards

I appreciate your work on this.  However, I'd prefer not to keep adding
more user-visible command line flags that we'll have to support for
backwards compat in the future.  The current approach in powerd is a
rough heuristic and with a little bit of work on good predictive
algorithms (see Summer of Code description on wiki), we won't need to
provide such specific tweaks.

If we are going to provide this kind of configurability, it should be in
a config file, not command line.  I'd like to see a power policy config
file that gives various profiles and events that cause a switch to each
policy.  Min/max would make sense there.

Again, I appreciate your work but don't want to continue down the
current path of powerd.  It needs to be a real power management utility
and have that flexibility.

-- 
Nate