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320ae51f JA |
1 | #include <linux/kernel.h> |
2 | #include <linux/threads.h> | |
3 | #include <linux/module.h> | |
4 | #include <linux/mm.h> | |
5 | #include <linux/smp.h> | |
6 | #include <linux/cpu.h> | |
7 | ||
8 | #include <linux/blk-mq.h> | |
9 | #include "blk.h" | |
10 | #include "blk-mq.h" | |
11 | ||
12 | static void show_map(unsigned int *map, unsigned int nr) | |
13 | { | |
14 | int i; | |
15 | ||
16 | pr_info("blk-mq: CPU -> queue map\n"); | |
17 | for_each_online_cpu(i) | |
18 | pr_info(" CPU%2u -> Queue %u\n", i, map[i]); | |
19 | } | |
20 | ||
21 | static int cpu_to_queue_index(unsigned int nr_cpus, unsigned int nr_queues, | |
22 | const int cpu) | |
23 | { | |
24 | return cpu / ((nr_cpus + nr_queues - 1) / nr_queues); | |
25 | } | |
26 | ||
27 | static int get_first_sibling(unsigned int cpu) | |
28 | { | |
29 | unsigned int ret; | |
30 | ||
31 | ret = cpumask_first(topology_thread_cpumask(cpu)); | |
32 | if (ret < nr_cpu_ids) | |
33 | return ret; | |
34 | ||
35 | return cpu; | |
36 | } | |
37 | ||
38 | int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues) | |
39 | { | |
40 | unsigned int i, nr_cpus, nr_uniq_cpus, queue, first_sibling; | |
41 | cpumask_var_t cpus; | |
42 | ||
43 | if (!alloc_cpumask_var(&cpus, GFP_ATOMIC)) | |
44 | return 1; | |
45 | ||
46 | cpumask_clear(cpus); | |
47 | nr_cpus = nr_uniq_cpus = 0; | |
48 | for_each_online_cpu(i) { | |
49 | nr_cpus++; | |
50 | first_sibling = get_first_sibling(i); | |
51 | if (!cpumask_test_cpu(first_sibling, cpus)) | |
52 | nr_uniq_cpus++; | |
53 | cpumask_set_cpu(i, cpus); | |
54 | } | |
55 | ||
56 | queue = 0; | |
57 | for_each_possible_cpu(i) { | |
58 | if (!cpu_online(i)) { | |
59 | map[i] = 0; | |
60 | continue; | |
61 | } | |
62 | ||
63 | /* | |
64 | * Easy case - we have equal or more hardware queues. Or | |
65 | * there are no thread siblings to take into account. Do | |
66 | * 1:1 if enough, or sequential mapping if less. | |
67 | */ | |
68 | if (nr_queues >= nr_cpus || nr_cpus == nr_uniq_cpus) { | |
69 | map[i] = cpu_to_queue_index(nr_cpus, nr_queues, queue); | |
70 | queue++; | |
71 | continue; | |
72 | } | |
73 | ||
74 | /* | |
75 | * Less then nr_cpus queues, and we have some number of | |
76 | * threads per cores. Map sibling threads to the same | |
77 | * queue. | |
78 | */ | |
79 | first_sibling = get_first_sibling(i); | |
80 | if (first_sibling == i) { | |
81 | map[i] = cpu_to_queue_index(nr_uniq_cpus, nr_queues, | |
82 | queue); | |
83 | queue++; | |
84 | } else | |
85 | map[i] = map[first_sibling]; | |
86 | } | |
87 | ||
88 | show_map(map, nr_cpus); | |
89 | free_cpumask_var(cpus); | |
90 | return 0; | |
91 | } | |
92 | ||
93 | unsigned int *blk_mq_make_queue_map(struct blk_mq_reg *reg) | |
94 | { | |
95 | unsigned int *map; | |
96 | ||
97 | /* If cpus are offline, map them to first hctx */ | |
98 | map = kzalloc_node(sizeof(*map) * num_possible_cpus(), GFP_KERNEL, | |
99 | reg->numa_node); | |
100 | if (!map) | |
101 | return NULL; | |
102 | ||
103 | if (!blk_mq_update_queue_map(map, reg->nr_hw_queues)) | |
104 | return map; | |
105 | ||
106 | kfree(map); | |
107 | return NULL; | |
108 | } |