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sched: Fix domain iteration

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Weird topologies can lead to asymmetric domain setups. This needs
further consideration since these setups are typically non-minimal
too.

For now, make it work by adding an extra mask selecting which CPUs
are allowed to iterate up.

The topology that triggered it is the one from David Rientjes:

	10 20 20 30
	20 10 20 20
	20 20 10 20
	30 20 20 10

resulting in boxes that wouldn't even boot.

Reported-by: David Rientjes <rientjes@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-3p86l9cuaqnxz7uxsojmz5rm@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra
2012-05-31 14:47:33 +02:00
committed by Ingo Molnar
parent 7f1b43936f
commit c117487687
4 changed files with 72 additions and 10 deletions
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11
include/linux/sched.h
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@@ -876,6 +876,8 @@ struct sched_group_power {
* Number of busy cpus in this group.
*/
atomic_t nr_busy_cpus;
unsigned long cpumask[0]; /* iteration mask */
};
struct sched_group {
@@ -900,6 +902,15 @@ static inline struct cpumask *sched_group_cpus(struct sched_group *sg)
return to_cpumask(sg->cpumask);
}
/*
* cpumask masking which cpus in the group are allowed to iterate up the domain
* tree.
*/
static inline struct cpumask *sched_group_mask(struct sched_group *sg)
{
return to_cpumask(sg->sgp->cpumask);
}
/**
* group_first_cpu - Returns the first cpu in the cpumask of a sched_group.
* @group: The group whose first cpu is to be returned.