From 406d394abfcd8f16dc1dbcc8fc1b828252befb6d Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 20 Jan 2023 20:24:31 -0800 Subject: [PATCH] cpumask: improve on cpumask_local_spread() locality Switch cpumask_local_spread() to use newly added sched_numa_find_nth_cpu(), which takes into account distances to each node in the system. For the following NUMA configuration: root@debian:~# numactl -H available: 4 nodes (0-3) node 0 cpus: 0 1 2 3 node 0 size: 3869 MB node 0 free: 3740 MB node 1 cpus: 4 5 node 1 size: 1969 MB node 1 free: 1937 MB node 2 cpus: 6 7 node 2 size: 1967 MB node 2 free: 1873 MB node 3 cpus: 8 9 10 11 12 13 14 15 node 3 size: 7842 MB node 3 free: 7723 MB node distances: node 0 1 2 3 0: 10 50 30 70 1: 50 10 70 30 2: 30 70 10 50 3: 70 30 50 10 The new cpumask_local_spread() traverses cpus for each node like this: node 0: 0 1 2 3 6 7 4 5 8 9 10 11 12 13 14 15 node 1: 4 5 8 9 10 11 12 13 14 15 0 1 2 3 6 7 node 2: 6 7 0 1 2 3 8 9 10 11 12 13 14 15 4 5 node 3: 8 9 10 11 12 13 14 15 4 5 6 7 0 1 2 3 Signed-off-by: Yury Norov Acked-by: Tariq Toukan Reviewed-by: Jacob Keller Reviewed-by: Peter Lafreniere Signed-off-by: Jakub Kicinski --- lib/cpumask.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/lib/cpumask.c b/lib/cpumask.c index c7c392514fd3..255974cd6734 100644 --- a/lib/cpumask.c +++ b/lib/cpumask.c @@ -110,7 +110,7 @@ void __init free_bootmem_cpumask_var(cpumask_var_t mask) #endif /** - * cpumask_local_spread - select the i'th cpu with local numa cpu's first + * cpumask_local_spread - select the i'th cpu based on NUMA distances * @i: index number * @node: local numa_node * @@ -132,15 +132,7 @@ unsigned int cpumask_local_spread(unsigned int i, int node) if (cpu < nr_cpu_ids) return cpu; } else { - /* NUMA first. */ - cpu = cpumask_nth_and(i, cpu_online_mask, cpumask_of_node(node)); - if (cpu < nr_cpu_ids) - return cpu; - - i -= cpumask_weight_and(cpu_online_mask, cpumask_of_node(node)); - - /* Skip NUMA nodes, done above. */ - cpu = cpumask_nth_andnot(i, cpu_online_mask, cpumask_of_node(node)); + cpu = sched_numa_find_nth_cpu(cpu_online_mask, i, node); if (cpu < nr_cpu_ids) return cpu; } -- 2.20.1