109 lines
2.3 KiB
C
109 lines
2.3 KiB
C
#include <linux/kernel.h>
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#include <linux/threads.h>
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#include <linux/module.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/cpu.h>
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#include <linux/blk-mq.h>
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#include "blk.h"
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#include "blk-mq.h"
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static void show_map(unsigned int *map, unsigned int nr)
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{
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int i;
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pr_info("blk-mq: CPU -> queue map\n");
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for_each_online_cpu(i)
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pr_info(" CPU%2u -> Queue %u\n", i, map[i]);
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}
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static int cpu_to_queue_index(unsigned int nr_cpus, unsigned int nr_queues,
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const int cpu)
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{
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return cpu / ((nr_cpus + nr_queues - 1) / nr_queues);
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}
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static int get_first_sibling(unsigned int cpu)
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{
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unsigned int ret;
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ret = cpumask_first(topology_thread_cpumask(cpu));
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if (ret < nr_cpu_ids)
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return ret;
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return cpu;
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}
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int blk_mq_update_queue_map(unsigned int *map, unsigned int nr_queues)
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{
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unsigned int i, nr_cpus, nr_uniq_cpus, queue, first_sibling;
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cpumask_var_t cpus;
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if (!alloc_cpumask_var(&cpus, GFP_ATOMIC))
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return 1;
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cpumask_clear(cpus);
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nr_cpus = nr_uniq_cpus = 0;
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for_each_online_cpu(i) {
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nr_cpus++;
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first_sibling = get_first_sibling(i);
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if (!cpumask_test_cpu(first_sibling, cpus))
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nr_uniq_cpus++;
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cpumask_set_cpu(i, cpus);
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}
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queue = 0;
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for_each_possible_cpu(i) {
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if (!cpu_online(i)) {
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map[i] = 0;
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continue;
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}
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/*
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* Easy case - we have equal or more hardware queues. Or
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* there are no thread siblings to take into account. Do
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* 1:1 if enough, or sequential mapping if less.
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*/
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if (nr_queues >= nr_cpus || nr_cpus == nr_uniq_cpus) {
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map[i] = cpu_to_queue_index(nr_cpus, nr_queues, queue);
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queue++;
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continue;
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}
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/*
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* Less then nr_cpus queues, and we have some number of
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* threads per cores. Map sibling threads to the same
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* queue.
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*/
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first_sibling = get_first_sibling(i);
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if (first_sibling == i) {
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map[i] = cpu_to_queue_index(nr_uniq_cpus, nr_queues,
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queue);
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queue++;
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} else
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map[i] = map[first_sibling];
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}
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show_map(map, nr_cpus);
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free_cpumask_var(cpus);
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return 0;
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}
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unsigned int *blk_mq_make_queue_map(struct blk_mq_reg *reg)
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{
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unsigned int *map;
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/* If cpus are offline, map them to first hctx */
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map = kzalloc_node(sizeof(*map) * num_possible_cpus(), GFP_KERNEL,
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reg->numa_node);
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if (!map)
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return NULL;
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if (!blk_mq_update_queue_map(map, reg->nr_hw_queues))
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return map;
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kfree(map);
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return NULL;
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}
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