Cgroups RT scheduling

Dhaval Giani dhaval at
Fri Sep 11 04:23:52 PDT 2009

[Adding peterz to the cc]

On Wed, Sep 09, 2009 at 04:49:52PM +0100, Rolando Martins wrote:
> Hi,
> I would like to confirm the following:
> cpuset.sched_load_balance doesn't work with RT, right?
> You cannot have tasks for sub-domain 2 to utilize bandwidth of
> sub-domain 3, right?
>                               __1__
>                              /        \
>                             2         3
>                       (50% rt)  (50% rt )
> For my application domain;) it would be interesting to have
> rt_runtime_ns as a min. of allocated rt and not a max.
> Ex. If an application of domain 2 needs to go up to 100% and domain 3
> is idle, then it would be cool to let it utilize the full bandwidth.
> (we also could have a hard upper limit in each sub-domain, like
> hard_up=0.8, i.e. even if we could get 100%, we will only utilize
> 80%).

As far as I understand, all RT group scheduling assures is a certain
bandwidth which you cannot exceed in a given time period. It doesn't
provide the guarantee (that I think you are looking for) that you want.

Peter should be able to tell more about future plans.


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