// 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;
|
}
|
|
int 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];
|
}
|
}
|
|
return 0;
|
}
|
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;
|
}
|
