[deliverable/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_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_sibling_cpumask(cpu));
	if (ret < nr_cpu_ids)
		return ret;

	return cpu;
}

int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues,
			    const struct cpumask *online_mask)
{
	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_cpu(i, online_mask) {
		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 (!cpumask_test_cpu(i, online_mask)) {
			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, cpu_online_mask))
		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 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
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
06931e62	27	ret = cpumask_first(topology_sibling_cpumask(cpu));
320ae51f JA	28	if (ret < nr_cpu_ids)
	29	return ret;
	30
	31	return cpu;
	32	}
	33
5778322e AM	34	int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues,
5778322e AM	35	const struct cpumask *online_mask)
320ae51f JA	36	{
	37	unsigned int i, nr_cpus, nr_uniq_cpus, queue, first_sibling;
	38	cpumask_var_t cpus;
	39
	40	if (!alloc_cpumask_var(&cpus, GFP_ATOMIC))
	41	return 1;
	42
	43	cpumask_clear(cpus);
	44	nr_cpus = nr_uniq_cpus = 0;
5778322e	45	for_each_cpu(i, online_mask) {
320ae51f JA	46	nr_cpus++;
	47	first_sibling = get_first_sibling(i);
	48	if (!cpumask_test_cpu(first_sibling, cpus))
	49	nr_uniq_cpus++;
	50	cpumask_set_cpu(i, cpus);
	51	}
	52
	53	queue = 0;
	54	for_each_possible_cpu(i) {
5778322e	55	if (!cpumask_test_cpu(i, online_mask)) {
320ae51f JA	56	map[i] = 0;
	57	continue;
	58	}
	59
	60	/*
	61	* Easy case - we have equal or more hardware queues. Or
	62	* there are no thread siblings to take into account. Do
	63	* 1:1 if enough, or sequential mapping if less.
	64	*/
	65	if (nr_queues >= nr_cpus \|\| nr_cpus == nr_uniq_cpus) {
	66	map[i] = cpu_to_queue_index(nr_cpus, nr_queues, queue);
	67	queue++;
	68	continue;
	69	}
	70
	71	/*
	72	* Less then nr_cpus queues, and we have some number of
	73	* threads per cores. Map sibling threads to the same
	74	* queue.
	75	*/
	76	first_sibling = get_first_sibling(i);
	77	if (first_sibling == i) {
	78	map[i] = cpu_to_queue_index(nr_uniq_cpus, nr_queues,
	79	queue);
	80	queue++;
	81	} else
	82	map[i] = map[first_sibling];
	83	}
	84
320ae51f JA	85	free_cpumask_var(cpus);
	86	return 0;
	87	}
	88
24d2f903	89	unsigned int blk_mq_make_queue_map(struct blk_mq_tag_set set)
320ae51f JA	90	{
	91	unsigned int *map;
	92
	93	/* If cpus are offline, map them to first hctx */
a33c1ba2	94	map = kzalloc_node(sizeof(map) nr_cpu_ids, GFP_KERNEL,
24d2f903	95	set->numa_node);
320ae51f JA	96	if (!map)
	97	return NULL;
	98
5778322e	99	if (!blk_mq_update_queue_map(map, set->nr_hw_queues, cpu_online_mask))
320ae51f JA	100	return map;
	101
	102	kfree(map);
	103	return NULL;
	104	}
f14bbe77 JA	105
	106	/*
	107	* We have no quick way of doing reverse lookups. This is only used at
	108	* queue init time, so runtime isn't important.
	109	*/
	110	int blk_mq_hw_queue_to_node(unsigned int *mq_map, unsigned int index)
	111	{
	112	int i;
	113
	114	for_each_possible_cpu(i) {
	115	if (index == mq_map[i])
bffed457	116	return local_memory_node(cpu_to_node(i));
f14bbe77 JA	117	}
	118
	119	return NUMA_NO_NODE;
	120	}