Messages in this thread | | | Date | Tue, 24 Jul 2007 13:14:29 -0700 (PDT) | From | david@lang ... | Subject | Re: Power Management framework proposal |
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On Tue, 24 Jul 2007, Benjamin Herrenschmidt wrote:
> On Sun, 2007-07-22 at 10:26 -0700, Arjan van de Ven wrote: >> On Sat, 2007-07-21 at 23:49 -0700, david@lang.hm wrote: >> >>> this approach would allow the transition of ALL drivers to the new mode of >>> operation in one fell swoop, and then adding additional power management >>> features is just adding to the existing list rather then implementing new >>> functions. >> >> >> I have a concern with this approach though. It seems to assume that >> there is one global thing somewhere that sets the system state; in my >> experience that is the wrong approach; in fact there is a very definite >> evidence that there are many decisions on power that are to be made >> local at a high frequency. An example of this is the processor speed; >> the ondemand governer does exactly this for the cpus that can switch >> speeds fast; it's just impossible to beat such a local, fast decision >> with anything on a global scale. >> >> On the other hand, some things (the high level goals and constraints) >> are obviously global. > > I think we need a set of constraints that trickle down the power tree > and limit what a given driver can do locally.
what sort of contraints are you thinking of?
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