On Tue 2009-12-22 13:10:36, Salman Qazi wrote: > On Fri, Dec 18, 2009 at 9:04 AM, Pavel Machek <pavel@xxxxxx> wrote: > > Hi > > > > > >> Why not use voltage and frequency scaling? > >> > >> Forced Idle Injection is more effective[1] and more widely available. > >> Even with voltage and frequency scaling, interpolation is needed > >> between the available settings. So, if we did use voltage and > > > > It is only more efficient on new hardware. > > > > You should also explain 'why not throttling' because that is actually > > designed for power capping. > > Do you mean t-states? Yes. > >> Application to Laptops and Cellphones: > >> > >> Imagine being in a tent in Death Valley with a laptop. You are bored, > >> and you want to watch a movie. However, you also want to do your best > >> to make the battery last and watch as much of the movie as possible. > >> Forced idle power capping is a solution. If your machine has a knob > >> that allows you to control the available power, you can turn that knob > >> until your video starts getting choppy. And then, turn the knob back > > > > That's bad example. Video player should already sleep between frames. > > Yes, the video player should sleep. However, there will be other > things running. And certainly, it is possible to cap the power and > discriminate so that those things are prevented from running while the > video player is allowed to run with minimal latency impact. I don't see how it would work without much of extra setup. Lets say your windowmanager wants to do some work, and you starve it indefinitely? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
