[PATCH 1/3] perf bench numa: fix incorrect NUMA toplogy assumption

[Alexander Gordeev]

The current code assumes that CPUs are evenly spread among
NUMA nodes. That is generally incorrect and leads to failure
on systems that have different NUMA topology.

Signed-off-by: Alexander Gordeev <agord...@linux.ibm.com>
---
 tools/perf/bench/numa.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/tools/perf/bench/numa.c b/tools/perf/bench/numa.c
index 5797253..23e224e 100644
--- a/tools/perf/bench/numa.c
+++ b/tools/perf/bench/numa.c
@@ -247,12 +247,13 @@ static int is_node_present(int node)
  */
 static bool node_has_cpus(int node)
 {
-       struct bitmask *cpu = numa_allocate_cpumask();
+       struct bitmask *cpumask = numa_allocate_cpumask();
        unsigned int i;
 
-       if (cpu && !numa_node_to_cpus(node, cpu)) {
-               for (i = 0; i < cpu->size; i++) {
-                       if (numa_bitmask_isbitset(cpu, i))
+       BUG_ON(!cpumask);
+       if (!numa_node_to_cpus(node, cpumask)) {
+               for (i = 0; i < cpumask->size; i++) {
+                       if (numa_bitmask_isbitset(cpumask, i))
                                return true;
                }
        }
@@ -288,14 +289,10 @@ static cpu_set_t bind_to_cpu(int target_cpu)
 
 static cpu_set_t bind_to_node(int target_node)
 {
-       int cpus_per_node = g->p.nr_cpus / nr_numa_nodes();
        cpu_set_t orig_mask, mask;
        int cpu;
        int ret;
 
-       BUG_ON(cpus_per_node * nr_numa_nodes() != g->p.nr_cpus);
-       BUG_ON(!cpus_per_node);
-
        ret = sched_getaffinity(0, sizeof(orig_mask), &orig_mask);
        BUG_ON(ret);
 
@@ -305,13 +302,15 @@ static cpu_set_t bind_to_node(int target_node)
                for (cpu = 0; cpu < g->p.nr_cpus; cpu++)
                        CPU_SET(cpu, &mask);
        } else {
-               int cpu_start = (target_node + 0) * cpus_per_node;
-               int cpu_stop  = (target_node + 1) * cpus_per_node;
-
-               BUG_ON(cpu_stop > g->p.nr_cpus);
+               struct bitmask *cpumask = numa_allocate_cpumask();
 
-               for (cpu = cpu_start; cpu < cpu_stop; cpu++)
-                       CPU_SET(cpu, &mask);
+               BUG_ON(!cpumask);
+               if (!numa_node_to_cpus(target_node, cpumask)) {
+                       for (cpu = 0; cpu < (int)cpumask->size; cpu++) {
+                               if (numa_bitmask_isbitset(cpumask, cpu))
+                                       CPU_SET(cpu, &mask);
+                       }
+               }
        }
 
        ret = sched_setaffinity(0, sizeof(mask), &mask);
-- 
1.8.3.1