spufs: switch to ->free_inode()
[muen/linux.git] / block / blk-mq-cpumap.c
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(struct blk_mq_queue_map *qmap,
18                               unsigned int nr_queues, const int cpu)
19 {
20         return qmap->queue_offset + (cpu % nr_queues);
21 }
22
23 static int get_first_sibling(unsigned int cpu)
24 {
25         unsigned int ret;
26
27         ret = cpumask_first(topology_sibling_cpumask(cpu));
28         if (ret < nr_cpu_ids)
29                 return ret;
30
31         return cpu;
32 }
33
34 int blk_mq_map_queues(struct blk_mq_queue_map *qmap)
35 {
36         unsigned int *map = qmap->mq_map;
37         unsigned int nr_queues = qmap->nr_queues;
38         unsigned int cpu, first_sibling;
39
40         for_each_possible_cpu(cpu) {
41                 /*
42                  * First do sequential mapping between CPUs and queues.
43                  * In case we still have CPUs to map, and we have some number of
44                  * threads per cores then map sibling threads to the same queue for
45                  * performace optimizations.
46                  */
47                 if (cpu < nr_queues) {
48                         map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
49                 } else {
50                         first_sibling = get_first_sibling(cpu);
51                         if (first_sibling == cpu)
52                                 map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
53                         else
54                                 map[cpu] = map[first_sibling];
55                 }
56         }
57
58         return 0;
59 }
60 EXPORT_SYMBOL_GPL(blk_mq_map_queues);
61
62 /*
63  * We have no quick way of doing reverse lookups. This is only used at
64  * queue init time, so runtime isn't important.
65  */
66 int blk_mq_hw_queue_to_node(struct blk_mq_queue_map *qmap, unsigned int index)
67 {
68         int i;
69
70         for_each_possible_cpu(i) {
71                 if (index == qmap->mq_map[i])
72                         return local_memory_node(cpu_to_node(i));
73         }
74
75         return NUMA_NO_NODE;
76 }