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| author |  Kyle Meyer <kyle.meyer@hpe.com>
| 2024-04-10 16:33:11 -0500 |
|---|---|---|
| committer |  Yury Norov <yury.norov@gmail.com>
| 2024-05-09 09:25:08 -0700 |
| commit | 05037e5f0f17935a86861f9610f941ebf346a95e (patch) | |
| tree | e018ce2d77e9abcadef1c7227343f26c03dfed70 /kernel/sched | |
| parent | cpumask: Add for_each_cpu_from() (diff) | |
| download | linux-05037e5f0f17935a86861f9610f941ebf346a95e.tar.gz linux-05037e5f0f17935a86861f9610f941ebf346a95e.tar.bz2 linux-05037e5f0f17935a86861f9610f941ebf346a95e.zip | |
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>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/topology.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 99ea5986038c..b6bcafc09969 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -2347,7 +2347,7 @@ static struct sched_domain *build_sched_domain(struct sched_domain_topology_leve static bool topology_span_sane(struct sched_domain_topology_level *tl, const struct cpumask *cpu_map, int cpu) { - int i; + int i = cpu + 1; /* NUMA levels are allowed to overlap */ if (tl->flags & SDTL_OVERLAP) @@ -2359,9 +2359,7 @@ static bool topology_span_sane(struct sched_domain_topology_level *tl, * breaking the sched_group lists - i.e. a later get_group() pass * breaks the linking done for an earlier span. */ - for_each_cpu(i, cpu_map) { - if (i == cpu) - continue; + for_each_cpu_from(i, cpu_map) { /* * We should 'and' all those masks with 'cpu_map' to exactly * match the topology we're about to build, but that can only |