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Linux kernel mirror (for testing)
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linux
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
14#include <linux/blk-mq.h>
15#include "blk.h"
16#include "blk-mq.h"
17
18static int cpu_to_queue_index(struct blk_mq_queue_map *qmap,
19 unsigned int nr_queues, const int cpu)
20{
21 return qmap->queue_offset + (cpu % nr_queues);
22}
23
24static int get_first_sibling(unsigned int cpu)
25{
26 unsigned int ret;
27
28 ret = cpumask_first(topology_sibling_cpumask(cpu));
29 if (ret < nr_cpu_ids)
30 return ret;
31
32 return cpu;
33}
34
35int blk_mq_map_queues(struct blk_mq_queue_map *qmap)
36{
37 unsigned int *map = qmap->mq_map;
38 unsigned int nr_queues = qmap->nr_queues;
39 unsigned int cpu, first_sibling;
40
41 for_each_possible_cpu(cpu) {
42 /*
43 * First do sequential mapping between CPUs and queues.
44 * In case we still have CPUs to map, and we have some number of
45 * threads per cores then map sibling threads to the same queue
46 * for performance optimizations.
47 */
48 if (cpu < nr_queues) {
49 map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
50 } else {
51 first_sibling = get_first_sibling(cpu);
52 if (first_sibling == cpu)
53 map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
54 else
55 map[cpu] = map[first_sibling];
56 }
57 }
58
59 return 0;
60}
61EXPORT_SYMBOL_GPL(blk_mq_map_queues);
62
63/**
64 * blk_mq_hw_queue_to_node - Look up the memory node for a hardware queue index
65 * @qmap: CPU to hardware queue map.
66 * @index: hardware queue index.
67 *
68 * We have no quick way of doing reverse lookups. This is only used at
69 * queue init time, so runtime isn't important.
70 */
71int blk_mq_hw_queue_to_node(struct blk_mq_queue_map *qmap, unsigned int index)
72{
73 int i;
74
75 for_each_possible_cpu(i) {
76 if (index == qmap->mq_map[i])
77 return local_memory_node(cpu_to_node(i));
78 }
79
80 return NUMA_NO_NODE;
81}