xref: /linux/block/blk-mq-cpumap.c (revision 90110e04)

// SPDX-License-Identifier: GPL-2.0
/*
 * CPU <-> hardware queue mapping helpers
 *
 * Copyright (C) 2013-2014 Jens Axboe
 */
#include <linux/kernel.h>
#include <linux/threads.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/group_cpus.h>

#include "blk.h"
#include "blk-mq.h"

void blk_mq_map_queues(struct blk_mq_queue_map *qmap)
{
	const struct cpumask *masks;
	unsigned int queue, cpu;

	masks = group_cpus_evenly(qmap->nr_queues);
	if (!masks) {
		for_each_possible_cpu(cpu)
			qmap->mq_map[cpu] = qmap->queue_offset;
		return;
	}

	for (queue = 0; queue < qmap->nr_queues; queue++) {
		for_each_cpu(cpu, &masks[queue])
			qmap->mq_map[cpu] = qmap->queue_offset + queue;
	}
	kfree(masks);
}
EXPORT_SYMBOL_GPL(blk_mq_map_queues);

/**
 * blk_mq_hw_queue_to_node - Look up the memory node for a hardware queue index
 * @qmap: CPU to hardware queue map.
 * @index: hardware queue index.
 *
 * We have no quick way of doing reverse lookups. This is only used at
 * queue init time, so runtime isn't important.
 */
int blk_mq_hw_queue_to_node(struct blk_mq_queue_map *qmap, unsigned int index)
{
	int i;

	for_each_possible_cpu(i) {
		if (index == qmap->mq_map[i])
			return cpu_to_node(i);
	}

	return NUMA_NO_NODE;
}