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