| 1 | /* |
| 2 | * CPU <-> hardware queue mapping helpers |
| 3 | * |
| 4 | * Copyright (C) 2013-2014 Jens Axboe |
| 5 | */ |
| 6 | #include <linux/kernel.h> |
| 7 | #include <linux/threads.h> |
| 8 | #include <linux/module.h> |
| 9 | #include <linux/mm.h> |
| 10 | #include <linux/smp.h> |
| 11 | #include <linux/cpu.h> |
| 12 | |
| 13 | #include <linux/blk-mq.h> |
| 14 | #include "blk.h" |
| 15 | #include "blk-mq.h" |
| 16 | |
| 17 | static int cpu_to_queue_index(unsigned int nr_queues, const int cpu) |
| 18 | { |
| 19 | return cpu % nr_queues; |
| 20 | } |
| 21 | |
| 22 | static int get_first_sibling(unsigned int cpu) |
| 23 | { |
| 24 | unsigned int ret; |
| 25 | |
| 26 | ret = cpumask_first(topology_sibling_cpumask(cpu)); |
| 27 | if (ret < nr_cpu_ids) |
| 28 | return ret; |
| 29 | |
| 30 | return cpu; |
| 31 | } |
| 32 | |
| 33 | int blk_mq_map_queues(struct blk_mq_tag_set *set) |
| 34 | { |
| 35 | unsigned int *map = set->mq_map; |
| 36 | unsigned int nr_queues = set->nr_hw_queues; |
| 37 | unsigned int cpu, first_sibling; |
| 38 | |
| 39 | for_each_possible_cpu(cpu) { |
| 40 | /* |
| 41 | * First do sequential mapping between CPUs and queues. |
| 42 | * In case we still have CPUs to map, and we have some number of |
| 43 | * threads per cores then map sibling threads to the same queue for |
| 44 | * performace optimizations. |
| 45 | */ |
| 46 | if (cpu < nr_queues) { |
| 47 | map[cpu] = cpu_to_queue_index(nr_queues, cpu); |
| 48 | } else { |
| 49 | first_sibling = get_first_sibling(cpu); |
| 50 | if (first_sibling == cpu) |
| 51 | map[cpu] = cpu_to_queue_index(nr_queues, cpu); |
| 52 | else |
| 53 | map[cpu] = map[first_sibling]; |
| 54 | } |
| 55 | } |
| 56 | |
| 57 | return 0; |
| 58 | } |
| 59 | EXPORT_SYMBOL_GPL(blk_mq_map_queues); |
| 60 | |
| 61 | /* |
| 62 | * We have no quick way of doing reverse lookups. This is only used at |
| 63 | * queue init time, so runtime isn't important. |
| 64 | */ |
| 65 | int blk_mq_hw_queue_to_node(unsigned int *mq_map, unsigned int index) |
| 66 | { |
| 67 | int i; |
| 68 | |
| 69 | for_each_possible_cpu(i) { |
| 70 | if (index == mq_map[i]) |
| 71 | return local_memory_node(cpu_to_node(i)); |
| 72 | } |
| 73 | |
| 74 | return NUMA_NO_NODE; |
| 75 | } |