Commit | Line | Data |
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75bb4625 JA |
1 | /* |
2 | * CPU <-> hardware queue mapping helpers | |
3 | * | |
4 | * Copyright (C) 2013-2014 Jens Axboe | |
5 | */ | |
320ae51f JA |
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 | ||
320ae51f JA |
17 | static int cpu_to_queue_index(unsigned int nr_cpus, unsigned int nr_queues, |
18 | const int cpu) | |
19 | { | |
959f5f5b | 20 | return cpu * nr_queues / nr_cpus; |
320ae51f JA |
21 | } |
22 | ||
23 | static int get_first_sibling(unsigned int cpu) | |
24 | { | |
25 | unsigned int ret; | |
26 | ||
27 | ret = cpumask_first(topology_thread_cpumask(cpu)); | |
28 | if (ret < nr_cpu_ids) | |
29 | return ret; | |
30 | ||
31 | return cpu; | |
32 | } | |
33 | ||
34 | int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues) | |
35 | { | |
36 | unsigned int i, nr_cpus, nr_uniq_cpus, queue, first_sibling; | |
37 | cpumask_var_t cpus; | |
38 | ||
39 | if (!alloc_cpumask_var(&cpus, GFP_ATOMIC)) | |
40 | return 1; | |
41 | ||
42 | cpumask_clear(cpus); | |
43 | nr_cpus = nr_uniq_cpus = 0; | |
44 | for_each_online_cpu(i) { | |
45 | nr_cpus++; | |
46 | first_sibling = get_first_sibling(i); | |
47 | if (!cpumask_test_cpu(first_sibling, cpus)) | |
48 | nr_uniq_cpus++; | |
49 | cpumask_set_cpu(i, cpus); | |
50 | } | |
51 | ||
52 | queue = 0; | |
53 | for_each_possible_cpu(i) { | |
54 | if (!cpu_online(i)) { | |
55 | map[i] = 0; | |
56 | continue; | |
57 | } | |
58 | ||
59 | /* | |
60 | * Easy case - we have equal or more hardware queues. Or | |
61 | * there are no thread siblings to take into account. Do | |
62 | * 1:1 if enough, or sequential mapping if less. | |
63 | */ | |
64 | if (nr_queues >= nr_cpus || nr_cpus == nr_uniq_cpus) { | |
65 | map[i] = cpu_to_queue_index(nr_cpus, nr_queues, queue); | |
66 | queue++; | |
67 | continue; | |
68 | } | |
69 | ||
70 | /* | |
71 | * Less then nr_cpus queues, and we have some number of | |
72 | * threads per cores. Map sibling threads to the same | |
73 | * queue. | |
74 | */ | |
75 | first_sibling = get_first_sibling(i); | |
76 | if (first_sibling == i) { | |
77 | map[i] = cpu_to_queue_index(nr_uniq_cpus, nr_queues, | |
78 | queue); | |
79 | queue++; | |
80 | } else | |
81 | map[i] = map[first_sibling]; | |
82 | } | |
83 | ||
320ae51f JA |
84 | free_cpumask_var(cpus); |
85 | return 0; | |
86 | } | |
87 | ||
24d2f903 | 88 | unsigned int *blk_mq_make_queue_map(struct blk_mq_tag_set *set) |
320ae51f JA |
89 | { |
90 | unsigned int *map; | |
91 | ||
92 | /* If cpus are offline, map them to first hctx */ | |
a33c1ba2 | 93 | map = kzalloc_node(sizeof(*map) * nr_cpu_ids, GFP_KERNEL, |
24d2f903 | 94 | set->numa_node); |
320ae51f JA |
95 | if (!map) |
96 | return NULL; | |
97 | ||
24d2f903 | 98 | if (!blk_mq_update_queue_map(map, set->nr_hw_queues)) |
320ae51f JA |
99 | return map; |
100 | ||
101 | kfree(map); | |
102 | return NULL; | |
103 | } | |
f14bbe77 JA |
104 | |
105 | /* | |
106 | * We have no quick way of doing reverse lookups. This is only used at | |
107 | * queue init time, so runtime isn't important. | |
108 | */ | |
109 | int blk_mq_hw_queue_to_node(unsigned int *mq_map, unsigned int index) | |
110 | { | |
111 | int i; | |
112 | ||
113 | for_each_possible_cpu(i) { | |
114 | if (index == mq_map[i]) | |
115 | return cpu_to_node(i); | |
116 | } | |
117 | ||
118 | return NUMA_NO_NODE; | |
119 | } |