Re: So, what's the status on the recent patches here?

[Mark Gross <mgross@linux.intel.com>]

On Sat, Aug 26, 2006 at 03:46:53PM +0200, Pavel Machek wrote:
> On Sat 2006-08-26 17:30:40, Vitaly Wool wrote:
> > Hi Pavel,
> > 
> > On 8/26/06, Pavel Machek <pavel@suse.cz> wrote:
> > >Hi!
> > >
> > >> >> No. The reason is there's no _real_ difference in 'fileserver' and
> > >> >> 'webserver' from the PM POV, so this will never happen.
> > >> >> There's no reason to introduce different policies for different use
> > >> >> cases which however imply similar peripherals utilization.
> > >> >> Moreover, I never play MP3s on a fileserver/webserver. The example
> > >> >> you've given is pretty much artificial.
> > >> >
> > >> >My notebook has 23 different devices. Do you really want to have
> > >> >8388608 policies for different perihepal utilizations?
> > >>
> > >> Can you please elaborate on how this number corresponds to the reality?
> > >> Looks like you don't catch what I'm saying. I'm talking about use
> > >> case-driven model in which you will need to invent 8388608 use cases
> > >> basically in order to have 8388608 policies. IOW, not any combination
> > >> is valid within these 8388608.
> > >
> > >I'm saying that usecase-driven model is not acceptable for a
> > >kernel. It is not kernel's business to limit user to particular usage
> > >models.
> > >
> > >That's why your model works for closed machines like a cellphones, but
> > >is totally broken for notebook. Sorry.
> > 
> > Who talks about kernel? A policy is an userspace thing. I guess we're
> > not quite understanding each other :)
> 
> You upload policies to kernel. You want 5 policies for your cellphone,
> and thats fine, but I'm telling you I'd need 8388608 policies for my
> notebook, because devices are independent and users want separate
> control.

No. Users do not, and if they do they won't deal directly with that large
of a number of power states.

Do not confuse policies with operating points.  The policies define the
sets of operating points that are valid at a given time and the policy
manager attempts to set the optimum OP.

The user will only deal with the set of policies exported by whatever
policy manager is in use.  Not the operating points.

power op is attempting to build a power management stack and is near the
bottom of the stack.

> 
> Because 8388608 policies is clearly not reasonable, powerop can not
> help here, and something better should be developed... like power
> domains someone proposed here.
> 
> (Or to say it in another words, powerop forces one big power domain,
> which is bad model for notebook-style machine).

I doubt notebook-style machines will ever us power op in any
significant way.  HPC and embedded will be the first users.

Power domains will likely build on top power op.

Power domains adds complexities themselves. Dealing with
dependencies and constraints between domains will be a challenge.

It is an interesting thought about implementing powerop interfaces on a
per power domain bases....

--mgross