1 // SPDX-License-Identifier: GPL-2.0 1 // SPDX-License-Identifier: GPL-2.0
2 /* 2 /*
3 * CPU <-> hardware queue mapping helpers 3 * CPU <-> hardware queue mapping helpers
4 * 4 *
5 * Copyright (C) 2013-2014 Jens Axboe 5 * Copyright (C) 2013-2014 Jens Axboe
6 */ 6 */
7 #include <linux/kernel.h> 7 #include <linux/kernel.h>
8 #include <linux/threads.h> 8 #include <linux/threads.h>
9 #include <linux/module.h> 9 #include <linux/module.h>
10 #include <linux/mm.h> 10 #include <linux/mm.h>
11 #include <linux/smp.h> 11 #include <linux/smp.h>
12 #include <linux/cpu.h> 12 #include <linux/cpu.h>
13 #include <linux/group_cpus.h> <<
14 13
>> 14 #include <linux/blk-mq.h>
15 #include "blk.h" 15 #include "blk.h"
16 #include "blk-mq.h" 16 #include "blk-mq.h"
17 17
>> 18 static int queue_index(struct blk_mq_queue_map *qmap,
>> 19 unsigned int nr_queues, const int q)
>> 20 {
>> 21 return qmap->queue_offset + (q % nr_queues);
>> 22 }
>> 23
>> 24 static 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
18 void blk_mq_map_queues(struct blk_mq_queue_map 35 void blk_mq_map_queues(struct blk_mq_queue_map *qmap)
19 { 36 {
20 const struct cpumask *masks; !! 37 unsigned int *map = qmap->mq_map;
21 unsigned int queue, cpu; !! 38 unsigned int nr_queues = qmap->nr_queues;
>> 39 unsigned int cpu, first_sibling, q = 0;
>> 40
>> 41 for_each_possible_cpu(cpu)
>> 42 map[cpu] = -1;
22 43
23 masks = group_cpus_evenly(qmap->nr_que !! 44 /*
24 if (!masks) { !! 45 * Spread queues among present CPUs first for minimizing
25 for_each_possible_cpu(cpu) !! 46 * count of dead queues which are mapped by all un-present CPUs
26 qmap->mq_map[cpu] = qm !! 47 */
27 return; !! 48 for_each_present_cpu(cpu) {
>> 49 if (q >= nr_queues)
>> 50 break;
>> 51 map[cpu] = queue_index(qmap, nr_queues, q++);
28 } 52 }
29 53
30 for (queue = 0; queue < qmap->nr_queue !! 54 for_each_possible_cpu(cpu) {
31 for_each_cpu(cpu, &masks[queue !! 55 if (map[cpu] != -1)
32 qmap->mq_map[cpu] = qm !! 56 continue;
>> 57 /*
>> 58 * First do sequential mapping between CPUs and queues.
>> 59 * In case we still have CPUs to map, and we have some number of
>> 60 * threads per cores then map sibling threads to the same queue
>> 61 * for performance optimizations.
>> 62 */
>> 63 if (q < nr_queues) {
>> 64 map[cpu] = queue_index(qmap, nr_queues, q++);
>> 65 } else {
>> 66 first_sibling = get_first_sibling(cpu);
>> 67 if (first_sibling == cpu)
>> 68 map[cpu] = queue_index(qmap, nr_queues, q++);
>> 69 else
>> 70 map[cpu] = map[first_sibling];
>> 71 }
33 } 72 }
34 kfree(masks); <<
35 } 73 }
36 EXPORT_SYMBOL_GPL(blk_mq_map_queues); 74 EXPORT_SYMBOL_GPL(blk_mq_map_queues);
37 75
38 /** 76 /**
39 * blk_mq_hw_queue_to_node - Look up the memor 77 * blk_mq_hw_queue_to_node - Look up the memory node for a hardware queue index
40 * @qmap: CPU to hardware queue map. 78 * @qmap: CPU to hardware queue map.
41 * @index: hardware queue index. 79 * @index: hardware queue index.
42 * 80 *
43 * We have no quick way of doing reverse looku 81 * We have no quick way of doing reverse lookups. This is only used at
44 * queue init time, so runtime isn't important 82 * queue init time, so runtime isn't important.
45 */ 83 */
46 int blk_mq_hw_queue_to_node(struct blk_mq_queu 84 int blk_mq_hw_queue_to_node(struct blk_mq_queue_map *qmap, unsigned int index)
47 { 85 {
48 int i; 86 int i;
49 87
50 for_each_possible_cpu(i) { 88 for_each_possible_cpu(i) {
51 if (index == qmap->mq_map[i]) 89 if (index == qmap->mq_map[i])
52 return cpu_to_node(i); 90 return cpu_to_node(i);
53 } 91 }
54 92
55 return NUMA_NO_NODE; 93 return NUMA_NO_NODE;
56 } 94 }
57 95
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