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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 | /* | |
20 | * Non present CPU will be mapped to queue index 0. | |
21 | */ | |
22 | if (!cpu_present(cpu)) | |
23 | return 0; | |
24 | return cpu % nr_queues; | |
25 | } | |
26 | ||
27 | static int get_first_sibling(unsigned int cpu) | |
28 | { | |
29 | unsigned int ret; | |
30 | ||
31 | ret = cpumask_first(topology_sibling_cpumask(cpu)); | |
32 | if (ret < nr_cpu_ids) | |
33 | return ret; | |
34 | ||
35 | return cpu; | |
36 | } | |
37 | ||
38 | int blk_mq_map_queues(struct blk_mq_tag_set *set) | |
39 | { | |
40 | unsigned int *map = set->mq_map; | |
41 | unsigned int nr_queues = set->nr_hw_queues; | |
42 | unsigned int cpu, first_sibling; | |
43 | ||
44 | for_each_possible_cpu(cpu) { | |
45 | /* | |
46 | * First do sequential mapping between CPUs and queues. | |
47 | * In case we still have CPUs to map, and we have some number of | |
48 | * threads per cores then map sibling threads to the same queue for | |
49 | * performace optimizations. | |
50 | */ | |
51 | if (cpu < nr_queues) { | |
52 | map[cpu] = cpu_to_queue_index(nr_queues, cpu); | |
53 | } else { | |
54 | first_sibling = get_first_sibling(cpu); | |
55 | if (first_sibling == cpu) | |
56 | map[cpu] = cpu_to_queue_index(nr_queues, cpu); | |
57 | else | |
58 | map[cpu] = map[first_sibling]; | |
59 | } | |
60 | } | |
61 | ||
62 | return 0; | |
63 | } | |
64 | EXPORT_SYMBOL_GPL(blk_mq_map_queues); | |
65 | ||
66 | /* | |
67 | * We have no quick way of doing reverse lookups. This is only used at | |
68 | * queue init time, so runtime isn't important. | |
69 | */ | |
70 | int blk_mq_hw_queue_to_node(unsigned int *mq_map, unsigned int index) | |
71 | { | |
72 | int i; | |
73 | ||
74 | for_each_possible_cpu(i) { | |
75 | if (index == mq_map[i]) | |
76 | return local_memory_node(cpu_to_node(i)); | |
77 | } | |
78 | ||
79 | return NUMA_NO_NODE; | |
80 | } |