On Tue, Feb 28, 2012 at 11:00:21PM +0100, Peter Zijlstra wrote:

On Tue, 2012-02-28 at 16:54 -0500, Vivek Goyal wrote:

quoted

On Tue, Feb 28, 2012 at 10:43:54PM +0100, Peter Zijlstra wrote:

quoted

On Tue, 2012-02-28 at 16:35 -0500, Vivek Goyal wrote:

quoted

For
cpu controller, it is priority at the group level no fixed minimum/maximum
% shares. And that's a limitation of treating task and group at same level.

Depends on what you mean by min/max %, you can do it on the group level
by using bandwidth caps (for max) or inverted (max on everybody else,
for min).

I was referring to using pure proportional controller. max bandwidth is
new and I am looking for a quick documentation file which describes
what are the knobs and how to use it. Did not find any in
Documentation/cgroups/. Is there any documentation available?

Its written in C, its at kernel/sched/fair.c ;-)

/me does not know enough of scheduler code to parse it fast. But now I found
Documentation/scheduler/sched-bwc.txt to explain what max bandwidth
control is.

quoted

I am assuming that max are being specified for groups in some absolute
quantity. That is fine. It will not still be max %, as again for % you
need fixed number of entities at any level and that's not the case with
tasks.

Minimum for one group (max for everyone else) will also only work if 
task and groups are not at same level.

I'm really not seeing this.

Assume I have following hierarchy.

				 root
			       /  |  \
			   Tasks  G1  G2

Assume I have given upper limit of 20% to G1. (period=50ms, quota=10ms), 
then it still does not gurantee the minimum bandwidth for G2. If I 
upper limit G2 also, then I am assuming it just gives minimum gurantee
for any tasks in root. (Right now I am assuming just 1 cpu in the system
for simplicity).

So to get a minimum % bandwdith gurantee for G2, I shall have to move
"Tasks" in a children group. Now both upper limit/proportional weight 
on G3 will help to determine minimum % share of G2.

				 root
			       /  |  \
			      G3  G1  G2
			      |
			     Tasks

Please correct me if I have understood the whole thing wrong.

Thanks
Vivek