[linux.git] / block / blk-mq-cpumap.c

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

static int queue_index(struct blk_mq_queue_map *qmap,
		       unsigned int nr_queues, const int q)
{
	return qmap->queue_offset + (q % nr_queues);
}

static int get_first_sibling(unsigned int cpu)
{
	unsigned int ret;

	ret = cpumask_first(topology_sibling_cpumask(cpu));
	if (ret < nr_cpu_ids)
		return ret;

	return cpu;
}

void blk_mq_map_queues(struct blk_mq_queue_map *qmap)
{
	unsigned int *map = qmap->mq_map;
	unsigned int nr_queues = qmap->nr_queues;
	unsigned int cpu, first_sibling, q = 0;

	for_each_possible_cpu(cpu)
		map[cpu] = -1;

	/*
	 * Spread queues among present CPUs first for minimizing
	 * count of dead queues which are mapped by all un-present CPUs
	 */
	for_each_present_cpu(cpu) {
		if (q >= nr_queues)
			break;
		map[cpu] = queue_index(qmap, nr_queues, q++);
	}

	for_each_possible_cpu(cpu) {
		if (map[cpu] != -1)
			continue;
		/*
		 * First do sequential mapping between CPUs and queues.
		 * In case we still have CPUs to map, and we have some number of
		 * threads per cores then map sibling threads to the same queue
		 * for performance optimizations.
		 */
		if (q < nr_queues) {
			map[cpu] = queue_index(qmap, nr_queues, q++);
		} else {
			first_sibling = get_first_sibling(cpu);
			if (first_sibling == cpu)
				map[cpu] = queue_index(qmap, nr_queues, q++);
			else
				map[cpu] = map[first_sibling];
		}
	}
}
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;
}
Commit	Line	Data
3dcf60bc	1	// SPDX-License-Identifier: GPL-2.0
75bb4625 JA	2	/*
	3	* CPU <-> hardware queue mapping helpers
	4	*
	5	* Copyright (C) 2013-2014 Jens Axboe
	6	*/
320ae51f JA	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
556f36e9 ML	18	static int queue_index(struct blk_mq_queue_map *qmap,
556f36e9 ML	19	unsigned int nr_queues, const int q)
320ae51f	20	{
556f36e9	21	return qmap->queue_offset + (q % nr_queues);
320ae51f JA	22	}
	23
	24	static int get_first_sibling(unsigned int cpu)
	25	{
	26	unsigned int ret;
	27
06931e62	28	ret = cpumask_first(topology_sibling_cpumask(cpu));
320ae51f JA	29	if (ret < nr_cpu_ids)
	30	return ret;
	31
	32	return cpu;
	33	}
	34
a4e1d0b7	35	void blk_mq_map_queues(struct blk_mq_queue_map *qmap)
320ae51f	36	{
ed76e329 JA	37	unsigned int *map = qmap->mq_map;
ed76e329 JA	38	unsigned int nr_queues = qmap->nr_queues;
556f36e9 ML	39	unsigned int cpu, first_sibling, q = 0;
	40
	41	for_each_possible_cpu(cpu)
	42	map[cpu] = -1;
	43
	44	/*
	45	* Spread queues among present CPUs first for minimizing
	46	* count of dead queues which are mapped by all un-present CPUs
	47	*/
	48	for_each_present_cpu(cpu) {
	49	if (q >= nr_queues)
	50	break;
	51	map[cpu] = queue_index(qmap, nr_queues, q++);
	52	}
320ae51f	53
fe631457	54	for_each_possible_cpu(cpu) {
556f36e9 ML	55	if (map[cpu] != -1)
556f36e9 ML	56	continue;
320ae51f	57	/*
fe631457 MG	58	* First do sequential mapping between CPUs and queues.
fe631457 MG	59	* In case we still have CPUs to map, and we have some number of
ef025d7e BVA	60	* threads per cores then map sibling threads to the same queue
ef025d7e BVA	61	* for performance optimizations.
320ae51f	62	*/
556f36e9 ML	63	if (q < nr_queues) {
556f36e9 ML	64	map[cpu] = queue_index(qmap, nr_queues, q++);
fe631457 MG	65	} else {
	66	first_sibling = get_first_sibling(cpu);
	67	if (first_sibling == cpu)
556f36e9	68	map[cpu] = queue_index(qmap, nr_queues, q++);
fe631457 MG	69	else
fe631457 MG	70	map[cpu] = map[first_sibling];
320ae51f	71	}
320ae51f	72	}
320ae51f	73	}
9e5a7e22	74	EXPORT_SYMBOL_GPL(blk_mq_map_queues);
320ae51f	75
cd669f88 BVA	76	/**
	77	* blk_mq_hw_queue_to_node - Look up the memory node for a hardware queue index
	78	* @qmap: CPU to hardware queue map.
	79	* @index: hardware queue index.
	80	*
f14bbe77 JA	81	* We have no quick way of doing reverse lookups. This is only used at
	82	* queue init time, so runtime isn't important.
	83	*/
ed76e329	84	int blk_mq_hw_queue_to_node(struct blk_mq_queue_map *qmap, unsigned int index)
f14bbe77 JA	85	{
	86	int i;
	87
	88	for_each_possible_cpu(i) {
ed76e329	89	if (index == qmap->mq_map[i])
576e85c5	90	return cpu_to_node(i);
f14bbe77 JA	91	}
	92
	93	return NUMA_NO_NODE;
	94	}