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authorSagi Grimberg <sagi@grimberg.me>2017-07-13 11:09:43 +0300
committerDoug Ledford <dledford@redhat.com>2017-08-08 14:58:03 -0400
commit24c5dc6610e8a3764fcb885cc3284c12ff1513de (patch)
tree4e63a3a4d5cff3d270598feb0d617c146ae20a41 /block/blk-mq-rdma.c
parent40b24403f33ed8e9401b087e25f46d002fc8f396 (diff)
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block: Add rdma affinity based queue mapping helper
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>
Diffstat (limited to 'block/blk-mq-rdma.c')
-rw-r--r--block/blk-mq-rdma.c52
1 files changed, 52 insertions, 0 deletions
diff --git a/block/blk-mq-rdma.c b/block/blk-mq-rdma.c
new file mode 100644
index 000000000000..996167f1de18
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+++ b/block/blk-mq-rdma.c
@@ -0,0 +1,52 @@
+/*
+ * 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);