Update on DeviceKit

[Matthew Garrett]

On Thu, May 08, 2008 at 10:56:45PM +0200, Holger Macht wrote:
> On Do 08. Mai - 21:50:42, Matthew Garrett wrote:
> > On Thu, May 08, 2008 at 10:38:43PM +0200, Holger Macht wrote:
> > 
> > > With you're argumentation being true, it wouldn't make sense to have
> > > something like an ondemand governor at all. Not to mention having an
> > > up_threshold exported to userspace. Just always run at full speed.
> > 
> > In an ideal universe, it wouldn't be. However, there's a (small) power 
> > cost involved in ramping up the voltage and frequency. If the amount of 
> > work to be done is sufficiently small, you can win (slightly) by staying 
> > at the lower frequency, and so ondemand makes sense.
> 
> So setting the up_threshold down, and thus staying a little bit longer at
> a low frequency, makes sense too.

Depending on your workload. Systems with bursty but short periods of 
work will benefit from different values when compared to systems doing 
longer periods of work. It can't be expressed as a linear scale, and at 
the point where you're exposing implementation details like that over an 
OS-agnostic abstraction layer, you've already failed.

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