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author | Peter Zijlstra <peterz@infradead.org> | 2012-05-23 16:00:43 (GMT) |
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committer | Ingo Molnar <mingo@kernel.org> | 2012-05-30 12:02:24 (GMT) |
commit | 74a5ce20e6eeeb3751340b390e7ac1d1d07bbf55 (patch) | |
tree | ebbef56666aa11303eafbfb6adbfce56e7a4c605 /kernel/sched/core.c | |
parent | 2ea45800d8e1c3c51c45a233d6bd6289a297a386 (diff) | |
download | linux-fsl-qoriq-74a5ce20e6eeeb3751340b390e7ac1d1d07bbf55.tar.xz |
sched: Fix SD_OVERLAP
SD_OVERLAP exists to allow overlapping groups, overlapping groups
appear in NUMA topologies that aren't fully connected.
The typical result of not fully connected NUMA is that each cpu (or
rather node) will have different spans for a particular distance.
However due to how sched domains are traversed -- only the first cpu
in the mask goes one level up -- the next level only cares about the
spans of the cpus that went up.
Due to this two things were observed to be broken:
- build_overlap_sched_groups() -- since its possible the cpu we're
building the groups for exists in multiple (or all) groups, the
selection criteria of the first group didn't ensure there was a cpu
for which is was true that cpumask_first(span) == cpu. Thus load-
balancing would terminate.
- update_group_power() -- assumed that the cpu span of the first
group of the domain was covered by all groups of the child domain.
The above explains why this isn't true, so deal with it.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: David Rientjes <rientjes@google.com>
Link: http://lkml.kernel.org/r/1337788843.9783.14.camel@laptop
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/core.c')
-rw-r--r-- | kernel/sched/core.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 5573361..3a69374 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6030,11 +6030,14 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu) cpumask_or(covered, covered, sg_span); - sg->sgp = *per_cpu_ptr(sdd->sgp, cpumask_first(sg_span)); + sg->sgp = *per_cpu_ptr(sdd->sgp, i); atomic_inc(&sg->sgp->ref); - if (cpumask_test_cpu(cpu, sg_span)) + if ((!groups && cpumask_test_cpu(cpu, sg_span)) || + cpumask_first(sg_span) == cpu) { + WARN_ON_ONCE(!cpumask_test_cpu(cpu, sg_span)); groups = sg; + } if (!first) first = sg; |