Help needed to implement parameter in SCHED_DEADLINE policy

[Henrik Austad]

On Fri, Dec 26, 2014 at 09:14:22PM +0530, Chanchal Paul wrote:
> Hi all,

Hi Paul,

> I am trying to implement my custom scheduling policy in rt patched
> linux kernel. I am working with version 3.14.25-rt22. I have
> successfully installed the kernel after patching with rt patch of same
> version.
> 
> Now the installed kernel also has SCHED_DEADLINE i.e. the EDF scheduling policy.
> 
> The problem in my hand is to introduce a parameter in the
> SCHED_DEADLINE policy which will further dynamically change the
> priority according to the supplied value while the task is submitted.

You do know that SCHED_DEADLINE does not use priorities but _deadlines_, 
right?

care to elaborate a bit?

> I have already simulated and tested my requirement. I am having
> problem with understanding the hierarchy of scheduler code.

You mean the order of the scheduling policies? If you look at the 
sched_class in the different classes, you'll find the following hierarchy:

stop_sched_class
dl_sched_class
rt_sched_class
fair_sched_class
idle_sched_class

So, first the scheduler sees if there's any deadline tasks, then -rt and so 
on.

I (we) need a bit more info about what exactly it is you're struggling with

> 
> Thanks in advance
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-- 
Henrik Austad