Re: A nice CPU resource controller

[Martin Ohlin <martin.ohlin@control.lth.se>]

Balbir Singh wrote:

> The CKRM e-series is a PID based CPU Controller. It did a good job of
> controlling and smoothing out the load (and variations) and even
> worked with groups. But it achieved all this through some amount of
> complexity. How do you plan to extend the idea to groups? Do you have
> any code that we can look at?

I would say that my controller so far is very simple, probably too 
simple. I have no detailed plan yet about how to incorporate groups of 
tasks, only small ideas that I would like to think a little more on 
before I say something embarrasing. The important code-parts are in the 
thesis, and I must say that the code is in no way finished, but most of 
it can be found at:
http://www.control.lth.se/user/martin.ohlin/linux/sampler.c

> I do not understand controlling the nice value? Most cpu control the
> bandwidth/time - are there any advantages to controlling the nice
> value? How does this interplay with dynamic priorities that the
> scheduler currently maintains?

There is a relationship between the nice value and the achieved 
bandwidth/time. Therefore it was possible that the nice value could be 
used to control the bandwidth/time. I wanted to know if it was possible 
to use it, and it was. As to the dynamic priorities, I do not change 
them, but as I do change the nice value and the dynamic priorities are 
relative to that, then you may say that I do change them... Anyway, it 
seems to work.

/Martin