blk-mq-rdma.c
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/*
* Copyright (c) 2017 Sagi Grimberg.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*/
#include <linux/blk-mq.h>
#include <linux/blk-mq-rdma.h>
#include <rdma/ib_verbs.h>
/**
* blk_mq_rdma_map_queues - provide a default queue mapping for rdma device
* @set: tagset to provide the mapping for
* @dev: rdma device associated with @set.
* @first_vec: first interrupt vectors to use for queues (usually 0)
*
* This function assumes the rdma device @dev has at least as many available
* interrupt vetors as @set has queues. It will then query it's affinity mask
* and built queue mapping that maps a queue to the CPUs that have irq affinity
* for the corresponding vector.
*
* In case either the driver passed a @dev with less vectors than
* @set->nr_hw_queues, or @dev does not provide an affinity mask for a
* vector, we fallback to the naive mapping.
*/
int blk_mq_rdma_map_queues(struct blk_mq_tag_set *set,
struct ib_device *dev, int first_vec)
{
const struct cpumask *mask;
unsigned int queue, cpu;
for (queue = 0; queue < set->nr_hw_queues; queue++) {
mask = ib_get_vector_affinity(dev, first_vec + queue);
if (!mask)
goto fallback;
for_each_cpu(cpu, mask)
set->mq_map[cpu] = queue;
}
return 0;
fallback:
return blk_mq_map_queues(set);
}
EXPORT_SYMBOL_GPL(blk_mq_rdma_map_queues);