blob: 8e61e8640e1701a8736ab791aaac79983bde6225 [file] [log] [blame]
Jens Axboe75bb4622014-05-28 10:15:41 -06001/*
2 * CPU <-> hardware queue mapping helpers
3 *
4 * Copyright (C) 2013-2014 Jens Axboe
5 */
Jens Axboe320ae512013-10-24 09:20:05 +01006#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
Jens Axboe320ae512013-10-24 09:20:05 +010017static int cpu_to_queue_index(unsigned int nr_cpus, unsigned int nr_queues,
18 const int cpu)
19{
Bart Van Assche959f5f52014-12-09 16:59:21 +010020 return cpu * nr_queues / nr_cpus;
Jens Axboe320ae512013-10-24 09:20:05 +010021}
22
23static int get_first_sibling(unsigned int cpu)
24{
25 unsigned int ret;
26
Bartosz Golaszewski06931e62015-05-26 15:11:28 +020027 ret = cpumask_first(topology_sibling_cpumask(cpu));
Jens Axboe320ae512013-10-24 09:20:05 +010028 if (ret < nr_cpu_ids)
29 return ret;
30
31 return cpu;
32}
33
Christoph Hellwigda695ba2016-09-14 16:18:55 +020034int blk_mq_map_queues(struct blk_mq_tag_set *set)
Jens Axboe320ae512013-10-24 09:20:05 +010035{
Christoph Hellwigda695ba2016-09-14 16:18:55 +020036 unsigned int *map = set->mq_map;
37 unsigned int nr_queues = set->nr_hw_queues;
38 const struct cpumask *online_mask = cpu_online_mask;
Jens Axboe320ae512013-10-24 09:20:05 +010039 unsigned int i, nr_cpus, nr_uniq_cpus, queue, first_sibling;
40 cpumask_var_t cpus;
41
42 if (!alloc_cpumask_var(&cpus, GFP_ATOMIC))
Christoph Hellwigda695ba2016-09-14 16:18:55 +020043 return -ENOMEM;
Jens Axboe320ae512013-10-24 09:20:05 +010044
45 cpumask_clear(cpus);
46 nr_cpus = nr_uniq_cpus = 0;
Akinobu Mita57783222015-09-27 02:09:23 +090047 for_each_cpu(i, online_mask) {
Jens Axboe320ae512013-10-24 09:20:05 +010048 nr_cpus++;
49 first_sibling = get_first_sibling(i);
50 if (!cpumask_test_cpu(first_sibling, cpus))
51 nr_uniq_cpus++;
52 cpumask_set_cpu(i, cpus);
53 }
54
55 queue = 0;
56 for_each_possible_cpu(i) {
Akinobu Mita57783222015-09-27 02:09:23 +090057 if (!cpumask_test_cpu(i, online_mask)) {
Jens Axboe320ae512013-10-24 09:20:05 +010058 map[i] = 0;
59 continue;
60 }
61
62 /*
63 * Easy case - we have equal or more hardware queues. Or
64 * there are no thread siblings to take into account. Do
65 * 1:1 if enough, or sequential mapping if less.
66 */
67 if (nr_queues >= nr_cpus || nr_cpus == nr_uniq_cpus) {
68 map[i] = cpu_to_queue_index(nr_cpus, nr_queues, queue);
69 queue++;
70 continue;
71 }
72
73 /*
74 * Less then nr_cpus queues, and we have some number of
75 * threads per cores. Map sibling threads to the same
76 * queue.
77 */
78 first_sibling = get_first_sibling(i);
79 if (first_sibling == i) {
80 map[i] = cpu_to_queue_index(nr_uniq_cpus, nr_queues,
81 queue);
82 queue++;
83 } else
84 map[i] = map[first_sibling];
85 }
86
Jens Axboe320ae512013-10-24 09:20:05 +010087 free_cpumask_var(cpus);
88 return 0;
89}
Christoph Hellwig9e5a7e22016-11-01 08:12:47 -060090EXPORT_SYMBOL_GPL(blk_mq_map_queues);
Jens Axboe320ae512013-10-24 09:20:05 +010091
Jens Axboef14bbe72014-05-27 12:06:53 -060092/*
93 * We have no quick way of doing reverse lookups. This is only used at
94 * queue init time, so runtime isn't important.
95 */
96int blk_mq_hw_queue_to_node(unsigned int *mq_map, unsigned int index)
97{
98 int i;
99
100 for_each_possible_cpu(i) {
101 if (index == mq_map[i])
Raghavendra K Tbffed452015-12-02 16:59:05 +0530102 return local_memory_node(cpu_to_node(i));
Jens Axboef14bbe72014-05-27 12:06:53 -0600103 }
104
105 return NUMA_NO_NODE;
106}