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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - block/blk-mq-cpumap.c
2 * CPU <-> hardware queue mapping helpers
4 * Copyright (C) 2013-2014 Jens Axboe
6 #include <linux/kernel.h>
7 #include <linux/threads.h>
8 #include <linux/module.h>
10 #include <linux/smp.h>
11 #include <linux/cpu.h>
13 #include <linux/blk-mq.h>
17 static int cpu_to_queue_index(unsigned int nr_cpus
, unsigned int nr_queues
,
20 return cpu
* nr_queues
/ nr_cpus
;
23 static int get_first_sibling(unsigned int cpu
)
27 ret
= cpumask_first(topology_sibling_cpumask(cpu
));
34 int blk_mq_map_queues(struct blk_mq_tag_set
*set
)
36 unsigned int *map
= set
->mq_map
;
37 unsigned int nr_queues
= set
->nr_hw_queues
;
38 const struct cpumask
*online_mask
= cpu_online_mask
;
39 unsigned int i
, nr_cpus
, nr_uniq_cpus
, queue
, first_sibling
;
42 if (!alloc_cpumask_var(&cpus
, GFP_ATOMIC
))
46 nr_cpus
= nr_uniq_cpus
= 0;
47 for_each_cpu(i
, online_mask
) {
49 first_sibling
= get_first_sibling(i
);
50 if (!cpumask_test_cpu(first_sibling
, cpus
))
52 cpumask_set_cpu(i
, cpus
);
56 for_each_possible_cpu(i
) {
57 if (!cpumask_test_cpu(i
, online_mask
)) {
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.
67 if (nr_queues
>= nr_cpus
|| nr_cpus
== nr_uniq_cpus
) {
68 map
[i
] = cpu_to_queue_index(nr_cpus
, nr_queues
, queue
);
74 * Less then nr_cpus queues, and we have some number of
75 * threads per cores. Map sibling threads to the same
78 first_sibling
= get_first_sibling(i
);
79 if (first_sibling
== i
) {
80 map
[i
] = cpu_to_queue_index(nr_uniq_cpus
, nr_queues
,
84 map
[i
] = map
[first_sibling
];
87 free_cpumask_var(cpus
);
90 EXPORT_SYMBOL_GPL(blk_mq_map_queues
);
93 * We have no quick way of doing reverse lookups. This is only used at
94 * queue init time, so runtime isn't important.
96 int blk_mq_hw_queue_to_node(unsigned int *mq_map
, unsigned int index
)
100 for_each_possible_cpu(i
) {
101 if (index
== mq_map
[i
])
102 return local_memory_node(cpu_to_node(i
));