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 18 static 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 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 35 int 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 for 46 * performace 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 } 61 EXPORT_SYMBOL_GPL(blk_mq_map_queues); 62 63 /* 64 * We have no quick way of doing reverse lookups. This is only used at 65 * queue init time, so runtime isn't important. 66 */ 67 int blk_mq_hw_queue_to_node(struct blk_mq_queue_map *qmap, unsigned int index) 68 { 69 int i; 70 71 for_each_possible_cpu(i) { 72 if (index == qmap->mq_map[i]) 73 return local_memory_node(cpu_to_node(i)); 74 } 75 76 return NUMA_NO_NODE; 77 } 78