1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * CPU <-> hardware queue mapping helpers
4 *
5 * Copyright (C) 2013-2014 Jens Axboe
6 */
7 #include <linux/kernel.h>
8 #include <linux/threads.h>
9 #include <linux/module.h>
10 #include <linux/mm.h>
11 #include <linux/smp.h>
12 #include <linux/cpu.h>
13 #include <linux/group_cpus.h>
14
15 #include "blk.h"
16 #include "blk-mq.h"
17
18 void blk_mq_map_queues(struct blk_mq_queue_map *qmap)
19 {
20 const struct cpumask *masks;
21 unsigned int queue, cpu;
22
23 masks = group_cpus_evenly(qmap->nr_queues);
24 if (!masks) {
25 for_each_possible_cpu(cpu)
26 qmap->mq_map[cpu] = qmap->queue_offset;
27 return;
28 }
29
30 for (queue = 0; queue < qmap->nr_queues; queue++) {
31 for_each_cpu(cpu, &masks[queue])
32 qmap->mq_map[cpu] = qmap->queue_offset + queue;
33 }
34 kfree(masks);
35 }
36 EXPORT_SYMBOL_GPL(blk_mq_map_queues);
37
38 /**
39 * blk_mq_hw_queue_to_node - Look up the memory node for a hardware queue index
40 * @qmap: CPU to hardware queue map.
41 * @index: hardware queue index.
42 *
43 * We have no quick way of doing reverse lookups. This is only used at
44 * queue init time, so runtime isn't important.
45 */
46 int blk_mq_hw_queue_to_node(struct blk_mq_queue_map *qmap, unsigned int index)
47 {
48 int i;
49
50 for_each_possible_cpu(i) {
51 if (index == qmap->mq_map[i])
52 return cpu_to_node(i);
53 }
54
55 return NUMA_NO_NODE;
56 }
57
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