Re: [PATCH 3/9] sched: add sched_numa_find_nth_cpu()

[Chen Yu]

On 2023-01-20 at 20:24:30 -0800, Yury Norov wrote:
> 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 <yury.norov@xxxxxxxxx>
> Acked-by: Tariq Toukan <tariqt@xxxxxxxxxx>
> Reviewed-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>
> Reviewed-by: Peter Lafreniere <peter@xxxxxxxx>
> ---
>  include/linux/topology.h |  8 ++++++
>  kernel/sched/topology.c  | 57 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 65 insertions(+)
>
[snip] 
> + * sched_numa_find_nth_cpu() - given the NUMA topology, find the Nth next cpu
> + *                             closest to @cpu from @cpumask.
Just minor question, the @cpu below is used as the index, right? What does "close to @cpu"
mean above?
> + * cpumask: cpumask to find a cpu from
> + * cpu: Nth cpu to find
Maybe also add description for @node?

thanks,
Chenyu