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