NUMA inter-node load balance

Hi, I'm a brazilian student and my research area is scalable operating 
systems. Currently, I'm studing the kernel 2.6.7 scheduler (specially 
for NUMA systems) and I din't find where inter-node load balance is 
done. There was a routine called balance_node in sched.c file in kernel 
2.6.5, but in version 2.6.7 the scheduler works with scheduler domains 
and CPU groups.
I read the sched.c code and I think the load balance is done for 
specific scheduler domain's CPU groups, but in the 
arch_init_sched_domains routine the highest level scheduler domain 
created is node scheduler domain. So, I can't understand how and when 
the inter-node load balance is performed. Is there a scheduler domain 
for the entire system? Where is it set up?

Sorry if this is a stupid question, I'm just a beginner and the Linux 
scheduler don´t have a good documentation, so I decided to ask to you.

Sorry too my terrible english and thank very much if someone read all 
this message! :)

I hope to receive an answer...

Thanks again.

Monica

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