]>
git.proxmox.com Git - mirror_ubuntu-artful-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_queues
, const int cpu
)
20 * Non present CPU will be mapped to queue index 0.
22 if (!cpu_present(cpu
))
24 return cpu
% nr_queues
;
27 static int get_first_sibling(unsigned int cpu
)
31 ret
= cpumask_first(topology_sibling_cpumask(cpu
));
38 int blk_mq_map_queues(struct blk_mq_tag_set
*set
)
40 unsigned int *map
= set
->mq_map
;
41 unsigned int nr_queues
= set
->nr_hw_queues
;
42 unsigned int cpu
, first_sibling
;
44 for_each_possible_cpu(cpu
) {
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.
51 if (cpu
< nr_queues
) {
52 map
[cpu
] = cpu_to_queue_index(nr_queues
, cpu
);
54 first_sibling
= get_first_sibling(cpu
);
55 if (first_sibling
== cpu
)
56 map
[cpu
] = cpu_to_queue_index(nr_queues
, cpu
);
58 map
[cpu
] = map
[first_sibling
];
64 EXPORT_SYMBOL_GPL(blk_mq_map_queues
);
67 * We have no quick way of doing reverse lookups. This is only used at
68 * queue init time, so runtime isn't important.
70 int blk_mq_hw_queue_to_node(unsigned int *mq_map
, unsigned int index
)
74 for_each_possible_cpu(i
) {
75 if (index
== mq_map
[i
])
76 return local_memory_node(cpu_to_node(i
));