]>
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1 // SPDX-License-Identifier: GPL-2.0
3 * CPU <-> hardware queue mapping helpers
5 * Copyright (C) 2013-2014 Jens Axboe
7 #include <linux/kernel.h>
8 #include <linux/threads.h>
9 #include <linux/module.h>
11 #include <linux/smp.h>
12 #include <linux/cpu.h>
14 #include <linux/blk-mq.h>
18 static int cpu_to_queue_index(struct blk_mq_queue_map
*qmap
,
19 unsigned int nr_queues
, const int cpu
)
21 return qmap
->queue_offset
+ (cpu
% nr_queues
);
24 static int get_first_sibling(unsigned int cpu
)
28 ret
= cpumask_first(topology_sibling_cpumask(cpu
));
35 int blk_mq_map_queues(struct blk_mq_queue_map
*qmap
)
37 unsigned int *map
= qmap
->mq_map
;
38 unsigned int nr_queues
= qmap
->nr_queues
;
39 unsigned int cpu
, first_sibling
;
41 for_each_possible_cpu(cpu
) {
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 for
46 * performace optimizations.
48 if (cpu
< nr_queues
) {
49 map
[cpu
] = cpu_to_queue_index(qmap
, nr_queues
, cpu
);
51 first_sibling
= get_first_sibling(cpu
);
52 if (first_sibling
== cpu
)
53 map
[cpu
] = cpu_to_queue_index(qmap
, nr_queues
, cpu
);
55 map
[cpu
] = map
[first_sibling
];
61 EXPORT_SYMBOL_GPL(blk_mq_map_queues
);
64 * We have no quick way of doing reverse lookups. This is only used at
65 * queue init time, so runtime isn't important.
67 int blk_mq_hw_queue_to_node(struct blk_mq_queue_map
*qmap
, unsigned int index
)
71 for_each_possible_cpu(i
) {
72 if (index
== qmap
->mq_map
[i
])
73 return local_memory_node(cpu_to_node(i
));