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 
blk_mq_map_queues(struct blk_mq_queue_map * qmap)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  */
blk_mq_hw_queue_to_node(struct blk_mq_queue_map * qmap,unsigned int index)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