Re: question on sched-rt group allocation cap: sched_rt_runtime_us

From: Peter Zijlstra
Date: Tue Sep 08 2009 - 04:42:41 EST


On Tue, 2009-09-08 at 00:08 -0700, Anirban Sinha wrote:

> > Actually there is, use cpusets to carve the system into partitions.
>
> hmm. ok. I looked at the code a little bit. It seems to me that the
> 'borrowing' of RT runtimes occurs only from rt runqueues belonging to
> the same root domain. And partition_sched_domains() is the only
> external interface that can be used to create root domain out of a CPU
> set. But then I think it needs to have CGROUPS/USER groups enabled?
> Right?

No you need cpusets, you create a partition by disabling load-balancing
on the top set, thereby only allowing load-balancing withing the
children.

The runtime sharing is a form of load-balancing.

CONFIG_CPUSETS=y

Documentation/cgroups/cpusets.txt

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