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sched/topology: Optimize topology_span_sane()
Optimize topology_span_sane() by removing duplicate comparisons. Since topology_span_sane() is called inside of for_each_cpu(), each previous CPU has already been compared against every other CPU. The current CPU only needs to be compared against higher-numbered CPUs. The total number of comparisons is reduced from N * (N - 1) to N * (N - 1) / 2 on each non-NUMA scheduling domain level. Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com> Reviewed-by: Yury Norov <yury.norov@gmail.com> Acked-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Yury Norov <yury.norov@gmail.com>
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@ -2347,7 +2347,7 @@ static struct sched_domain *build_sched_domain(struct sched_domain_topology_leve
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static bool topology_span_sane(struct sched_domain_topology_level *tl,
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const struct cpumask *cpu_map, int cpu)
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{
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int i;
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int i = cpu + 1;
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/* NUMA levels are allowed to overlap */
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if (tl->flags & SDTL_OVERLAP)
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@ -2359,9 +2359,7 @@ static bool topology_span_sane(struct sched_domain_topology_level *tl,
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* breaking the sched_group lists - i.e. a later get_group() pass
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* breaks the linking done for an earlier span.
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*/
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for_each_cpu(i, cpu_map) {
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if (i == cpu)
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continue;
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for_each_cpu_from(i, cpu_map) {
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/*
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* We should 'and' all those masks with 'cpu_map' to exactly
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* match the topology we're about to build, but that can only
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