[mirror_ubuntu-bionic-kernel.git] / block / blk-mq-cpumap.c

/*
 * 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 cpu_to_queue_index(unsigned int nr_queues, const int cpu,
			      const struct cpumask *online_mask)
{
	/*
	 * Non online CPU will be mapped to queue index 0.
	 */
	if (!cpumask_test_cpu(cpu, online_mask))
		return 0;
	return cpu % 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;
}

int blk_mq_map_queues(struct blk_mq_tag_set *set)
{
	unsigned int *map = set->mq_map;
	unsigned int nr_queues = set->nr_hw_queues;
	const struct cpumask *online_mask = cpu_online_mask;
	unsigned int cpu, first_sibling;

	for_each_possible_cpu(cpu) {
		/*
		 * 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
		 * performace optimizations.
		 */
		if (cpu < nr_queues) {
			map[cpu] = cpu_to_queue_index(nr_queues, cpu, online_mask);
		} else {
			first_sibling = get_first_sibling(cpu);
			if (first_sibling == cpu)
				map[cpu] = cpu_to_queue_index(nr_queues, cpu, online_mask);
			else
				map[cpu] = map[first_sibling];
		}
	}

	return 0;
}
EXPORT_SYMBOL_GPL(blk_mq_map_queues);

/*
 * 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(unsigned int *mq_map, unsigned int index)
{
	int i;

	for_each_possible_cpu(i) {
		if (index == mq_map[i])
			return local_memory_node(cpu_to_node(i));
	}

	return NUMA_NO_NODE;
}
Commit	Line	Data
75bb4625 JA	1	/*
	2	* CPU <-> hardware queue mapping helpers
	3	*
	4	* Copyright (C) 2013-2014 Jens Axboe
	5	*/
320ae51f JA	6	#include <linux/kernel.h>
	7	#include <linux/threads.h>
	8	#include <linux/module.h>
	9	#include <linux/mm.h>
	10	#include <linux/smp.h>
	11	#include <linux/cpu.h>
	12
	13	#include <linux/blk-mq.h>
	14	#include "blk.h"
	15	#include "blk-mq.h"
	16
fe631457 MG	17	static int cpu_to_queue_index(unsigned int nr_queues, const int cpu,
fe631457 MG	18	const struct cpumask *online_mask)
320ae51f	19	{
fe631457 MG	20	/*
	21	* Non online CPU will be mapped to queue index 0.
	22	*/
	23	if (!cpumask_test_cpu(cpu, online_mask))
	24	return 0;
	25	return cpu % nr_queues;
320ae51f JA	26	}
	27
	28	static int get_first_sibling(unsigned int cpu)
	29	{
	30	unsigned int ret;
	31
06931e62	32	ret = cpumask_first(topology_sibling_cpumask(cpu));
320ae51f JA	33	if (ret < nr_cpu_ids)
	34	return ret;
	35
	36	return cpu;
	37	}
	38
da695ba2	39	int blk_mq_map_queues(struct blk_mq_tag_set *set)
320ae51f	40	{
da695ba2 CH	41	unsigned int *map = set->mq_map;
	42	unsigned int nr_queues = set->nr_hw_queues;
	43	const struct cpumask *online_mask = cpu_online_mask;
fe631457	44	unsigned int cpu, first_sibling;
320ae51f	45
fe631457	46	for_each_possible_cpu(cpu) {
320ae51f	47	/*
fe631457 MG	48	* First do sequential mapping between CPUs and queues.
	49	* In case we still have CPUs to map, and we have some number of
	50	* threads per cores then map sibling threads to the same queue for
	51	* performace optimizations.
320ae51f	52	*/
fe631457 MG	53	if (cpu < nr_queues) {
	54	map[cpu] = cpu_to_queue_index(nr_queues, cpu, online_mask);
	55	} else {
	56	first_sibling = get_first_sibling(cpu);
	57	if (first_sibling == cpu)
	58	map[cpu] = cpu_to_queue_index(nr_queues, cpu, online_mask);
	59	else
	60	map[cpu] = map[first_sibling];
320ae51f	61	}
320ae51f JA	62	}
320ae51f JA	63
320ae51f JA	64	return 0;
320ae51f JA	65	}
9e5a7e22	66	EXPORT_SYMBOL_GPL(blk_mq_map_queues);
320ae51f	67
f14bbe77 JA	68	/*
	69	* We have no quick way of doing reverse lookups. This is only used at
	70	* queue init time, so runtime isn't important.
	71	*/
	72	int blk_mq_hw_queue_to_node(unsigned int *mq_map, unsigned int index)
	73	{
	74	int i;
	75
	76	for_each_possible_cpu(i) {
	77	if (index == mq_map[i])
bffed457	78	return local_memory_node(cpu_to_node(i));
f14bbe77 JA	79	}
	80
	81	return NUMA_NO_NODE;
	82	}