fairsched for o(1)-scheduler

Given I've got spare time now, I'm trying to revive and finally have a working implementation for the 2.6 fairsched patch.

Since my early attempts crashed, I would appreciate peer review and advise on how to do a first implementation.

I was told that printk should not be used inside the scheduler, is this true?

Also, in order to park tasks aside, I created another prio_array besides the active and expired ones, queuing expired tasks there until the used could afford to move them to the active one. Does the scheduler assume, in implicit form, that a task is either on the active or expired array?

The proposed design is described at this page:

http://wind.cocodriloo.com/~wind/fairsched/

And also by Hubertus Franke on his OLS 2003 paper:

http://archive.linuxsymposium.org/ols2003/Proceedings/All-Reprints/Reprint-Franke-OLS2003.pdf

Greets, Antonio.

1. Dado un programa, siempre tiene al menos un fallo.
2. Dadas varias lineas de codigo, siempre se pueden acortar a menos lineas.
3. Por induccion, todos los programas se pueden
   reducir a una linea que no funciona.