tree e4cfb8255d62621d17bc08ee5f94f42a0cc22677
parent 4a55bd5e97b1775913f88f11108a4f144f590e89
author Peter Zijlstra <a.p.zijlstra@chello.nl> 1208627100 +0200
committer Ingo Molnar <mingo@elte.hu> 1208627100 +0200

sched: fair: weight calculations

In order to level the hierarchy, we need to calculate load based on the
root view. That is, each task's load is in the same unit.

             A
            / \
           B   1
          / \
         2   3

To compute 1's load we do:

	   weight(1)
	--------------
	 rq_weight(A)

To compute 2's load we do:

	  weight(2)      weight(B)
	------------ * -----------
	rq_weight(B)   rw_weight(A)

This yields load fractions in comparable units.

The consequence is that it changes virtual time. We used to have:

                time_{i}
  vtime_{i} = ------------
               weight_{i}

  vtime = \Sum vtime_{i} = time / rq_weight.

But with the new way of load calculation we get that vtime equals time.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>