block/blk-mq-cpumap.c

   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
  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  */
  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 }