blob: f68959341c0faa87809531af1a508dde6978feef [file] [log] [blame]
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/cpu.h>
static int get_first_sibling(unsigned int cpu)
unsigned int ret;
ret = cpumask_first(topology_sibling_cpumask(cpu));
if (ret < nr_cpu_ids)
return ret;
return cpu;
* Take a map of online CPUs and the number of available interrupt vectors
* and generate an output cpumask suitable for spreading MSI/MSI-X vectors
* so that they are distributed as good as possible around the CPUs. If
* more vectors than CPUs are available we'll map one to each CPU,
* otherwise we map one to the first sibling of each socket.
* If there are more vectors than CPUs we will still only have one bit
* set per CPU, but interrupt code will keep on assigning the vectors from
* the start of the bitmap until we run out of vectors.
struct cpumask *irq_create_affinity_mask(unsigned int *nr_vecs)
struct cpumask *affinity_mask;
unsigned int max_vecs = *nr_vecs;
if (max_vecs == 1)
return NULL;
affinity_mask = kzalloc(cpumask_size(), GFP_KERNEL);
if (!affinity_mask) {
*nr_vecs = 1;
return NULL;
if (max_vecs >= num_online_cpus()) {
cpumask_copy(affinity_mask, cpu_online_mask);
*nr_vecs = num_online_cpus();
} else {
unsigned int vecs = 0, cpu;
for_each_online_cpu(cpu) {
if (cpu == get_first_sibling(cpu)) {
cpumask_set_cpu(cpu, affinity_mask);
if (--max_vecs == 0)
*nr_vecs = vecs;
return affinity_mask;