]> pilppa.com Git - linux-2.6-omap-h63xx.git/commit
sched: fair: weight calculations
authorPeter Zijlstra <a.p.zijlstra@chello.nl>
Sat, 19 Apr 2008 17:45:00 +0000 (19:45 +0200)
committerIngo Molnar <mingo@elte.hu>
Sat, 19 Apr 2008 17:45:00 +0000 (19:45 +0200)
commit8f1bc385cfbab474db6c27b5af1e439614f3025c
treee4cfb8255d62621d17bc08ee5f94f42a0cc22677
parent4a55bd5e97b1775913f88f11108a4f144f590e89
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>
kernel/sched.c
kernel/sched_fair.c