On Thu, 2012-02-23 at 16:38 -0500, Vivek Goyal wrote:

quoted

quoted

Again, it does not mean I am advocating flat hiearchy. I am just wondering
in case of fully nested hierarchies (task at same level as groups), how
does one explain it to a layman user who understands things in terms of
% of resources. 

If your complete control is % based then I would assume its a % of a %.
Simple enough.

But % of % will vary dynamically and not be static. So if root has got
100% of resources and we want 25% of that for a group, then hierarchy
might look as follows.

                                root
                                / | \
                               T1 T2 g1

T1, T2 are tasks and g1 is the group needing 25% of root's resources. Now
number of tasks running in parallel to g1 will determine its effective %
and tasks come and go. So the only way to do this would be that move T1
and T2 in a child group under root and make sure new tasks don't show up
in root. 

Which is exactly that the scheduler stuff does.. so tough luck for the
sysad who can't grasp it.

Otherwise creating a group under root does not ensure that you get minimum
% of resource. It just makes sure that you can't get more than 25% of
% resources when things are tight. 

You never said anything about minimum resource guarantees in the initial
problem statement.