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https://github.com/torvalds/linux
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24c5dc6610
Like pci and virtio, we add a rdma helper for affinity spreading. This achieves optimal mq affinity assignments according to the underlying rdma device affinity maps. Reviewed-by: Jens Axboe <axboe@fb.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Max Gurtovoy <maxg@mellanox.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Doug Ledford <dledford@redhat.com>
52 lines
1.7 KiB
C
52 lines
1.7 KiB
C
/*
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* Copyright (c) 2017 Sagi Grimberg.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*/
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#include <linux/blk-mq.h>
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#include <linux/blk-mq-rdma.h>
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#include <rdma/ib_verbs.h>
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/**
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* blk_mq_rdma_map_queues - provide a default queue mapping for rdma device
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* @set: tagset to provide the mapping for
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* @dev: rdma device associated with @set.
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* @first_vec: first interrupt vectors to use for queues (usually 0)
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*
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* This function assumes the rdma device @dev has at least as many available
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* interrupt vetors as @set has queues. It will then query it's affinity mask
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* and built queue mapping that maps a queue to the CPUs that have irq affinity
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* for the corresponding vector.
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*
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* In case either the driver passed a @dev with less vectors than
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* @set->nr_hw_queues, or @dev does not provide an affinity mask for a
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* vector, we fallback to the naive mapping.
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*/
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int blk_mq_rdma_map_queues(struct blk_mq_tag_set *set,
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struct ib_device *dev, int first_vec)
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{
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const struct cpumask *mask;
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unsigned int queue, cpu;
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for (queue = 0; queue < set->nr_hw_queues; queue++) {
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mask = ib_get_vector_affinity(dev, first_vec + queue);
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if (!mask)
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goto fallback;
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for_each_cpu(cpu, mask)
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set->mq_map[cpu] = queue;
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}
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return 0;
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fallback:
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return blk_mq_map_queues(set);
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}
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EXPORT_SYMBOL_GPL(blk_mq_rdma_map_queues);
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