]>
git.proxmox.com Git - mirror_ubuntu-zesty-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_cpus
+ nr_queues
- 1) / nr_queues
);
23 static int get_first_sibling(unsigned int cpu
)
27 ret
= cpumask_first(topology_thread_cpumask(cpu
));
34 int blk_mq_update_queue_map(unsigned int *map
, unsigned int nr_queues
)
36 unsigned int i
, nr_cpus
, nr_uniq_cpus
, queue
, first_sibling
;
39 if (!alloc_cpumask_var(&cpus
, GFP_ATOMIC
))
43 nr_cpus
= nr_uniq_cpus
= 0;
44 for_each_online_cpu(i
) {
46 first_sibling
= get_first_sibling(i
);
47 if (!cpumask_test_cpu(first_sibling
, cpus
))
49 cpumask_set_cpu(i
, cpus
);
53 for_each_possible_cpu(i
) {
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.
64 if (nr_queues
>= nr_cpus
|| nr_cpus
== nr_uniq_cpus
) {
65 map
[i
] = cpu_to_queue_index(nr_cpus
, nr_queues
, queue
);
71 * Less then nr_cpus queues, and we have some number of
72 * threads per cores. Map sibling threads to the same
75 first_sibling
= get_first_sibling(i
);
76 if (first_sibling
== i
) {
77 map
[i
] = cpu_to_queue_index(nr_uniq_cpus
, nr_queues
,
81 map
[i
] = map
[first_sibling
];
84 free_cpumask_var(cpus
);
88 unsigned int *blk_mq_make_queue_map(struct blk_mq_tag_set
*set
)
92 /* If cpus are offline, map them to first hctx */
93 map
= kzalloc_node(sizeof(*map
) * num_possible_cpus(), GFP_KERNEL
,
98 if (!blk_mq_update_queue_map(map
, set
->nr_hw_queues
))
106 * We have no quick way of doing reverse lookups. This is only used at
107 * queue init time, so runtime isn't important.
109 int blk_mq_hw_queue_to_node(unsigned int *mq_map
, unsigned int index
)
113 for_each_possible_cpu(i
) {
114 if (index
== mq_map
[i
])
115 return cpu_to_node(i
);