Re: [RFC 0/5] sched: Add CPU rate caps

[Peter Williams <pwil3058@bigpond.net.au>]

Sam Vilain wrote:
> Peter Williams wrote:
>
> > They shouldn't interfere as which scheduler to use is a boot time 
> > selection and only one scheduler is in force.  It's mainly a coding 
> > matter and in particular whether the "scheduler driver" interface would 
> > need to be modified or whether your scheduler can be implemented using 
> > the current interface.
> >  
>
> Yes, that's the key issue I think - the interface now has more inputs.
>
> > > I guess the big question is - is there a corresponding concept in
> > > > PlugSched?  for instance, is there a reference in the task_struct to the
> > > > current scheduling domain, or is it more CKRM-style with classification
> > > > modules?
> > >    
> > It uses the standard run queue structure with per scheduler
> > modifications (via a union) to handle the different ways that the
> > schedulers manage priority arrays (so yes). As I said it restricts
> > itself to scheduling matters within each run queue and leaves the
> > wider aspects to the normal code.
>
>
> Ok, so there is no existing "classification" abstraction?  The
> classification is tied to the scheduler implementation?

Yes.

> > At first guess, it sounds like adding your scheduler could be as simple 
> > as taking a copy of ingosched.c (which is the implementation of the 
> > standard scheduler within PlugSched) and then making your modifications. 
> >  You could probably even share the same run queue components but 
> > there's nothing to stop you adding new ones.
> >
> > Each scheduler can also have its own per task data via a union in the 
> > task struct.
> >  
>
> Ok, sounds like that problem is solved - just the classification one
> remaining.
>
> > OK.  I'm waiting for the next -mm kernel before I make the next release.
> >  
>
> Looking forward to it.

Andrew released 2.6.17-rc5-mm1 yesterday so I should have a new version 
in a day or two.

Peter
--
Peter Williams                                   pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
 -- Ambrose Bierce
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