1 // SPDX-License-Identifier: GPL-2.0 <<
2 /* 1 /*
3 * CPU <-> hardware queue mapping helpers 2 * CPU <-> hardware queue mapping helpers
4 * 3 *
5 * Copyright (C) 2013-2014 Jens Axboe 4 * Copyright (C) 2013-2014 Jens Axboe
6 */ 5 */
7 #include <linux/kernel.h> 6 #include <linux/kernel.h>
8 #include <linux/threads.h> 7 #include <linux/threads.h>
9 #include <linux/module.h> 8 #include <linux/module.h>
10 #include <linux/mm.h> 9 #include <linux/mm.h>
11 #include <linux/smp.h> 10 #include <linux/smp.h>
12 #include <linux/cpu.h> 11 #include <linux/cpu.h>
13 #include <linux/group_cpus.h> <<
14 12
>> 13 #include <linux/blk-mq.h>
15 #include "blk.h" 14 #include "blk.h"
16 #include "blk-mq.h" 15 #include "blk-mq.h"
17 16
18 void blk_mq_map_queues(struct blk_mq_queue_map !! 17 static int cpu_to_queue_index(unsigned int nr_cpus, unsigned int nr_queues,
>> 18 const int cpu)
19 { 19 {
20 const struct cpumask *masks; !! 20 return cpu * nr_queues / nr_cpus;
21 unsigned int queue, cpu; !! 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_update_queue_map(unsigned int *map, unsigned int nr_queues,
>> 35 const struct cpumask *online_mask)
>> 36 {
>> 37 unsigned int i, nr_cpus, nr_uniq_cpus, queue, first_sibling;
>> 38 cpumask_var_t cpus;
22 39
23 masks = group_cpus_evenly(qmap->nr_que !! 40 if (!alloc_cpumask_var(&cpus, GFP_ATOMIC))
24 if (!masks) { !! 41 return 1;
25 for_each_possible_cpu(cpu) !! 42
26 qmap->mq_map[cpu] = qm !! 43 cpumask_clear(cpus);
27 return; !! 44 nr_cpus = nr_uniq_cpus = 0;
>> 45 for_each_cpu(i, online_mask) {
>> 46 nr_cpus++;
>> 47 first_sibling = get_first_sibling(i);
>> 48 if (!cpumask_test_cpu(first_sibling, cpus))
>> 49 nr_uniq_cpus++;
>> 50 cpumask_set_cpu(i, cpus);
28 } 51 }
29 52
30 for (queue = 0; queue < qmap->nr_queue !! 53 queue = 0;
31 for_each_cpu(cpu, &masks[queue !! 54 for_each_possible_cpu(i) {
32 qmap->mq_map[cpu] = qm !! 55 if (!cpumask_test_cpu(i, online_mask)) {
>> 56 map[i] = 0;
>> 57 continue;
>> 58 }
>> 59
>> 60 /*
>> 61 * Easy case - we have equal or more hardware queues. Or
>> 62 * there are no thread siblings to take into account. Do
>> 63 * 1:1 if enough, or sequential mapping if less.
>> 64 */
>> 65 if (nr_queues >= nr_cpus || nr_cpus == nr_uniq_cpus) {
>> 66 map[i] = cpu_to_queue_index(nr_cpus, nr_queues, queue);
>> 67 queue++;
>> 68 continue;
>> 69 }
>> 70
>> 71 /*
>> 72 * Less then nr_cpus queues, and we have some number of
>> 73 * threads per cores. Map sibling threads to the same
>> 74 * queue.
>> 75 */
>> 76 first_sibling = get_first_sibling(i);
>> 77 if (first_sibling == i) {
>> 78 map[i] = cpu_to_queue_index(nr_uniq_cpus, nr_queues,
>> 79 queue);
>> 80 queue++;
>> 81 } else
>> 82 map[i] = map[first_sibling];
33 } 83 }
34 kfree(masks); !! 84
>> 85 free_cpumask_var(cpus);
>> 86 return 0;
35 } 87 }
36 EXPORT_SYMBOL_GPL(blk_mq_map_queues); <<
37 88
38 /** !! 89 unsigned int *blk_mq_make_queue_map(struct blk_mq_tag_set *set)
39 * blk_mq_hw_queue_to_node - Look up the memor !! 90 {
40 * @qmap: CPU to hardware queue map. !! 91 unsigned int *map;
41 * @index: hardware queue index. !! 92
42 * !! 93 /* If cpus are offline, map them to first hctx */
>> 94 map = kzalloc_node(sizeof(*map) * nr_cpu_ids, GFP_KERNEL,
>> 95 set->numa_node);
>> 96 if (!map)
>> 97 return NULL;
>> 98
>> 99 if (!blk_mq_update_queue_map(map, set->nr_hw_queues, cpu_online_mask))
>> 100 return map;
>> 101
>> 102 kfree(map);
>> 103 return NULL;
>> 104 }
>> 105
>> 106 /*
43 * We have no quick way of doing reverse looku 107 * We have no quick way of doing reverse lookups. This is only used at
44 * queue init time, so runtime isn't important 108 * queue init time, so runtime isn't important.
45 */ 109 */
46 int blk_mq_hw_queue_to_node(struct blk_mq_queu !! 110 int blk_mq_hw_queue_to_node(unsigned int *mq_map, unsigned int index)
47 { 111 {
48 int i; 112 int i;
49 113
50 for_each_possible_cpu(i) { 114 for_each_possible_cpu(i) {
51 if (index == qmap->mq_map[i]) !! 115 if (index == mq_map[i])
52 return cpu_to_node(i); 116 return cpu_to_node(i);
53 } 117 }
54 118
55 return NUMA_NO_NODE; 119 return NUMA_NO_NODE;
56 } 120 }
57 121
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