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 <linux/blk-mq.h>
  16 #include "blk.h"
  17 #include "blk-mq.h"
  18
  19 void blk_mq_map_queues(struct blk_mq_queue_map *qmap)
  20 {
  21         const struct cpumask *masks;
  22         unsigned int queue, cpu;
  23
  24         masks = group_cpus_evenly(qmap->nr_queues);
  25         if (!masks) {
  26                 for_each_possible_cpu(cpu)
  27                         qmap->mq_map[cpu] = qmap->queue_offset;
  28                 return;
  29         }
  30
  31         for (queue = 0; queue < qmap->nr_queues; queue++) {
  32                 for_each_cpu(cpu, &masks[queue])
  33                         qmap->mq_map[cpu] = qmap->queue_offset + queue;
  34         }
  35         kfree(masks);
  36 }
  37 EXPORT_SYMBOL_GPL(blk_mq_map_queues);
  38
  39 /**
  40  * blk_mq_hw_queue_to_node - Look up the memory node for a hardware queue index
  41  * @qmap: CPU to hardware queue map.
  42  * @index: hardware queue index.
  43  *
  44  * We have no quick way of doing reverse lookups. This is only used at
  45  * queue init time, so runtime isn't important.
  46  */
  47 int blk_mq_hw_queue_to_node(struct blk_mq_queue_map *qmap, unsigned int index)
  48 {
  49         int i;
  50
  51         for_each_possible_cpu(i) {
  52                 if (index == qmap->mq_map[i])
  53                         return cpu_to_node(i);
  54         }
  55
  56         return NUMA_NO_NODE;
  57 }