diff options
| -rw-r--r-- | block/blk-mq-cpumap.c | 68 |
1 files changed, 22 insertions, 46 deletions
diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c index 8e61e8640e17..2cca4fc43f45 100644 --- a/block/blk-mq-cpumap.c +++ b/block/blk-mq-cpumap.c @@ -14,10 +14,15 @@ #include "blk.h" #include "blk-mq.h" -static int cpu_to_queue_index(unsigned int nr_cpus, unsigned int nr_queues, - const int cpu) +static int cpu_to_queue_index(unsigned int nr_queues, const int cpu, + const struct cpumask *online_mask) { - return cpu * nr_queues / nr_cpus; + /* + * Non online CPU will be mapped to queue index 0. + */ + if (!cpumask_test_cpu(cpu, online_mask)) + return 0; + return cpu % nr_queues; } static int get_first_sibling(unsigned int cpu) @@ -36,55 +41,26 @@ int blk_mq_map_queues(struct blk_mq_tag_set *set) unsigned int *map = set->mq_map; unsigned int nr_queues = set->nr_hw_queues; const struct cpumask *online_mask = cpu_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 -ENOMEM; - - 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); - } - - queue = 0; - for_each_possible_cpu(i) { - if (!cpumask_test_cpu(i, online_mask)) { - map[i] = 0; - continue; - } + unsigned int cpu, first_sibling; + for_each_possible_cpu(cpu) { /* - * Easy case - we have equal or more hardware queues. Or - * there are no thread siblings to take into account. Do - * 1:1 if enough, or sequential mapping if less. + * 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 (nr_queues >= nr_cpus || nr_cpus == nr_uniq_cpus) { - map[i] = cpu_to_queue_index(nr_cpus, nr_queues, queue); - queue++; - continue; + if (cpu < nr_queues) { + map[cpu] = cpu_to_queue_index(nr_queues, cpu, online_mask); + } else { + first_sibling = get_first_sibling(cpu); + if (first_sibling == cpu) + map[cpu] = cpu_to_queue_index(nr_queues, cpu, online_mask); + else + map[cpu] = map[first_sibling]; } - - /* - * Less then nr_cpus queues, and we have some number of - * threads per cores. Map sibling threads to the same - * queue. - */ - first_sibling = get_first_sibling(i); - if (first_sibling == i) { - map[i] = cpu_to_queue_index(nr_uniq_cpus, nr_queues, - queue); - queue++; - } else - map[i] = map[first_sibling]; } - free_cpumask_var(cpus); return 0; } EXPORT_SYMBOL_GPL(blk_mq_map_queues); |