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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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5
kernel/sched/fair.c
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@@ -3652,7 +3652,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
int i;
if (local_group)
balance_cpu = group_first_cpu(group);
balance_cpu = group_balance_cpu(group);
/* Tally up the load of all CPUs in the group */
max_cpu_load = 0;
@@ -3667,7 +3667,8 @@ static inline void update_sg_lb_stats(struct lb_env *env,
/* Bias balancing toward cpus of our domain */
if (local_group) {
if (idle_cpu(i) && !first_idle_cpu) {
if (idle_cpu(i) && !first_idle_cpu &&
cpumask_test_cpu(i, sched_group_mask(group))) {
first_idle_cpu = 1;
balance_cpu = i;
}