/*
* 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);
vecs++;
}
if (--max_vecs == 0)
break;
}
*nr_vecs = vecs;
}
return affinity_mask;
}
int blk_mq_map_queues(struct blk_mq_queue_map *qmap)
{
unsigned int *map = qmap->mq_map;
unsigned int nr_queues = qmap->nr_queues;
unsigned int cpu, first_sibling;
for_each_possible_cpu(cpu) {
/*
* First do sequential mapping between CPUs and queues.
* In case we still have CPUs to map, and we have some number of
* threads per cores then map sibling threads to the same queue for
* performace optimizations.
*/
if (cpu < nr_queues) {
map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
} else {
first_sibling = get_first_sibling(cpu);
if (first_sibling == cpu)
map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
else
map[cpu] = map[first_sibling];
}
}
return 0;
}
int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues,
const struct cpumask *online_mask)
{
unsigned int i, nr_cpus, nr_uniq_cpus, queue, first_sibling;
cpumask_var_t cpus;
if (!alloc_cpumask_var(&cpus, GFP_ATOMIC))
return 1;
cpumask_clear(cpus);
nr_cpus = nr_uniq_cpus = 0;
for_each_cpu(i, online_mask) {
nr_cpus++;
first_sibling = get_first_sibling(i);
if (!cpumask_test_cpu(first_sibling, cpus))
nr_uniq_cpus++;
cpumask_set_cpu(i, cpus);
}