[linux.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)
{
	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;
	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);
		} else {
			first_sibling = get_first_sibling(cpu);
			if (first_sibling == cpu)
				map[cpu] = cpu_to_queue_index(nr_queues, cpu);
			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
03ffbcdd	17	static int cpu_to_queue_index(unsigned int nr_queues, const int cpu)
320ae51f	18	{
fe631457	19	return cpu % nr_queues;
320ae51f JA	20	}
	21
	22	static int get_first_sibling(unsigned int cpu)
	23	{
	24	unsigned int ret;
	25
06931e62	26	ret = cpumask_first(topology_sibling_cpumask(cpu));
320ae51f JA	27	if (ret < nr_cpu_ids)
	28	return ret;
	29
	30	return cpu;
	31	}
	32
da695ba2	33	int blk_mq_map_queues(struct blk_mq_tag_set *set)
320ae51f	34	{
da695ba2 CH	35	unsigned int *map = set->mq_map;
da695ba2 CH	36	unsigned int nr_queues = set->nr_hw_queues;
fe631457	37	unsigned int cpu, first_sibling;
320ae51f	38
fe631457	39	for_each_possible_cpu(cpu) {
320ae51f	40	/*
fe631457 MG	41	* First do sequential mapping between CPUs and queues.
	42	* In case we still have CPUs to map, and we have some number of
	43	* threads per cores then map sibling threads to the same queue for
	44	* performace optimizations.
320ae51f	45	*/
fe631457	46	if (cpu < nr_queues) {
03ffbcdd	47	map[cpu] = cpu_to_queue_index(nr_queues, cpu);
fe631457 MG	48	} else {
	49	first_sibling = get_first_sibling(cpu);
	50	if (first_sibling == cpu)
03ffbcdd	51	map[cpu] = cpu_to_queue_index(nr_queues, cpu);
fe631457 MG	52	else
fe631457 MG	53	map[cpu] = map[first_sibling];
320ae51f	54	}
320ae51f JA	55	}
320ae51f JA	56
320ae51f JA	57	return 0;
320ae51f JA	58	}
9e5a7e22	59	EXPORT_SYMBOL_GPL(blk_mq_map_queues);
320ae51f	60
f14bbe77 JA	61	/*
	62	* We have no quick way of doing reverse lookups. This is only used at
	63	* queue init time, so runtime isn't important.
	64	*/
	65	int blk_mq_hw_queue_to_node(unsigned int *mq_map, unsigned int index)
	66	{
	67	int i;
	68
	69	for_each_possible_cpu(i) {
	70	if (index == mq_map[i])
bffed457	71	return local_memory_node(cpu_to_node(i));
f14bbe77 JA	72	}
	73
	74	return NUMA_NO_NODE;
	75	}