Update on DeviceKit

[Matthew Garrett]

On Thu, May 08, 2008 at 03:04:36PM +0200, Holger Macht wrote:
> On Thu 08. May - 13:35:11, Matthew Garrett wrote:
> > I'm not convinced that fine tuning is something that can be done in a 
> > generic way. It's going to be kernel specific, and there's no sense in 
> > having it tweakable at a per-user level. Trying to fit it into any sort 
> > of dbus interface would basically just be exposing the sysfs interface 
> > over dbus, which doesn't sound like a great idea...
> 
> We're already doing this quite successful.
> 
> SetCPUFreqPerformance method abstracts all the different sysfs entries of
> CPUFreq with one single setting (1 to 100, corresponding to the
> performance you get).

Well, yes, but what does that mean? You can't rate performance on a 
scale of 0-100 - there's multiple factors at play. Is performance a 
latency issue? A raw power one? What should the thresholds for ondemand 
be? If you're altering multiple factors, then for some workloads a 
higher value may yield lower performance. If you're only altering one 
factor, you may not be obtaining maximum performance for that power 
consumption. Trying to squash this into a linear scale doesn't work.

-- 
Matthew Garrett | mjg59 at srcf.ucam.org