[linux-2.6-block.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_cpus, unsigned int nr_queues,
			      const int cpu)
{
	return cpu * nr_queues / nr_cpus;
}

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

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

	return cpu;
}

int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues)
{
	unsigned int i, nr_cpus, nr_uniq_cpus, queue, first_sibling;
	cpumask_var_t cpus;

	if (!alloc_cpumask_var(&cpus, GFP_ATOMIC))
		return 1;

	cpumask_clear(cpus);
	nr_cpus = nr_uniq_cpus = 0;
	for_each_online_cpu(i) {
		nr_cpus++;
		first_sibling = get_first_sibling(i);
		if (!cpumask_test_cpu(first_sibling, cpus))
			nr_uniq_cpus++;
		cpumask_set_cpu(i, cpus);
	}

	queue = 0;
	for_each_possible_cpu(i) {
		if (!cpu_online(i)) {
			map[i] = 0;
			continue;
		}

		/*
		 * Easy case - we have equal or more hardware queues. Or
		 * there are no thread siblings to take into account. Do
		 * 1:1 if enough, or sequential mapping if less.
		 */
		if (nr_queues >= nr_cpus || nr_cpus == nr_uniq_cpus) {
			map[i] = cpu_to_queue_index(nr_cpus, nr_queues, queue);
			queue++;
			continue;
		}

		/*
		 * Less then nr_cpus queues, and we have some number of
		 * threads per cores. Map sibling threads to the same
		 * queue.
		 */
		first_sibling = get_first_sibling(i);
		if (first_sibling == i) {
			map[i] = cpu_to_queue_index(nr_uniq_cpus, nr_queues,
							queue);
			queue++;
		} else
			map[i] = map[first_sibling];
	}

	free_cpumask_var(cpus);
	return 0;
}

unsigned int *blk_mq_make_queue_map(struct blk_mq_tag_set *set)
{
	unsigned int *map;

	/* If cpus are offline, map them to first hctx */
	map = kzalloc_node(sizeof(*map) * nr_cpu_ids, GFP_KERNEL,
				set->numa_node);
	if (!map)
		return NULL;

	if (!blk_mq_update_queue_map(map, set->nr_hw_queues))
		return map;

	kfree(map);
	return NULL;
}

/*
 * 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 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
320ae51f JA	17	static int cpu_to_queue_index(unsigned int nr_cpus, unsigned int nr_queues,
	18	const int cpu)
	19	{
959f5f5b	20	return cpu * nr_queues / nr_cpus;
320ae51f JA	21	}
	22
	23	static int get_first_sibling(unsigned int cpu)
	24	{
	25	unsigned int ret;
	26
	27	ret = cpumask_first(topology_thread_cpumask(cpu));
	28	if (ret < nr_cpu_ids)
	29	return ret;
	30
	31	return cpu;
	32	}
	33
	34	int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues)
	35	{
	36	unsigned int i, nr_cpus, nr_uniq_cpus, queue, first_sibling;
	37	cpumask_var_t cpus;
	38
	39	if (!alloc_cpumask_var(&cpus, GFP_ATOMIC))
	40	return 1;
	41
	42	cpumask_clear(cpus);
	43	nr_cpus = nr_uniq_cpus = 0;
	44	for_each_online_cpu(i) {
	45	nr_cpus++;
	46	first_sibling = get_first_sibling(i);
	47	if (!cpumask_test_cpu(first_sibling, cpus))
	48	nr_uniq_cpus++;
	49	cpumask_set_cpu(i, cpus);
	50	}
	51
	52	queue = 0;
	53	for_each_possible_cpu(i) {
	54	if (!cpu_online(i)) {
	55	map[i] = 0;
	56	continue;
	57	}
	58
	59	/*
	60	* Easy case - we have equal or more hardware queues. Or
	61	* there are no thread siblings to take into account. Do
	62	* 1:1 if enough, or sequential mapping if less.
	63	*/
	64	if (nr_queues >= nr_cpus \|\| nr_cpus == nr_uniq_cpus) {
	65	map[i] = cpu_to_queue_index(nr_cpus, nr_queues, queue);
	66	queue++;
	67	continue;
	68	}
	69
	70	/*
	71	* Less then nr_cpus queues, and we have some number of
	72	* threads per cores. Map sibling threads to the same
	73	* queue.
	74	*/
	75	first_sibling = get_first_sibling(i);
	76	if (first_sibling == i) {
	77	map[i] = cpu_to_queue_index(nr_uniq_cpus, nr_queues,
	78	queue);
	79	queue++;
	80	} else
	81	map[i] = map[first_sibling];
	82	}
	83
320ae51f JA	84	free_cpumask_var(cpus);
	85	return 0;
	86	}
	87
24d2f903	88	unsigned int blk_mq_make_queue_map(struct blk_mq_tag_set set)
320ae51f JA	89	{
	90	unsigned int *map;
	91
	92	/* If cpus are offline, map them to first hctx */
a33c1ba2	93	map = kzalloc_node(sizeof(map) nr_cpu_ids, GFP_KERNEL,
24d2f903	94	set->numa_node);
320ae51f JA	95	if (!map)
	96	return NULL;
	97
24d2f903	98	if (!blk_mq_update_queue_map(map, set->nr_hw_queues))
320ae51f JA	99	return map;
	100
	101	kfree(map);
	102	return NULL;
	103	}
f14bbe77 JA	104
	105	/*
	106	* We have no quick way of doing reverse lookups. This is only used at
	107	* queue init time, so runtime isn't important.
	108	*/
	109	int blk_mq_hw_queue_to_node(unsigned int *mq_map, unsigned int index)
	110	{
	111	int i;
	112
	113	for_each_possible_cpu(i) {
	114	if (index == mq_map[i])
	115	return cpu_to_node(i);
	116	}
	117
	118	return NUMA_NO_NODE;
	119	}