From cd7f55359c90a4108e6528e326b8623fce1ad72a Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 20 Jan 2023 20:24:30 -0800 Subject: sched: add sched_numa_find_nth_cpu() The function finds Nth set CPU in a given cpumask starting from a given node. Leveraging the fact that each hop in sched_domains_numa_masks includes the same or greater number of CPUs than the previous one, we can use binary search on hops instead of linear walk, which makes the overall complexity of O(log n) in terms of number of cpumask_weight() calls. Signed-off-by: Yury Norov Acked-by: Tariq Toukan Reviewed-by: Jacob Keller Reviewed-by: Peter Lafreniere Signed-off-by: Jakub Kicinski --- include/linux/topology.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/linux/topology.h') diff --git a/include/linux/topology.h b/include/linux/topology.h index 4564faafd0e1..72f264575698 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -245,5 +245,13 @@ static inline const struct cpumask *cpu_cpu_mask(int cpu) return cpumask_of_node(cpu_to_node(cpu)); } +#ifdef CONFIG_NUMA +int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node); +#else +static __always_inline int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node) +{ + return cpumask_nth(cpu, cpus); +} +#endif /* CONFIG_NUMA */ #endif /* _LINUX_TOPOLOGY_H */ -- cgit v1.2.3