rdma: Enable ib_alloc_cq to spread work over a device's comp_vectors

Send and Receive completion is handled on a single CPU selected at
the time each Completion Queue is allocated. Typically this is when
an initiator instantiates an RDMA transport, or when a target
accepts an RDMA connection.

Some ULPs cannot open a connection per CPU to spread completion
workload across available CPUs and MSI vectors. For such ULPs,
provide an API that allows the RDMA core to select a completion
vector based on the device's complement of available comp_vecs.

ULPs that invoke ib_alloc_cq() with only comp_vector 0 are converted
to use the new API so that their completion workloads interfere less
with each other.

Suggested-by: Håkon Bugge <[email protected]>
Signed-off-by: Chuck Lever <[email protected]>
Reviewed-by: Leon Romanovsky <[email protected]>
Cc: <[email protected]>
Cc: <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Doug Ledford <[email protected]>

1 files changed, 19 insertions, 0 deletions

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index c5f8a9f17063..2a1523ccd7ab 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -3711,6 +3711,25 @@ static inline struct ib_cq *ib_alloc_cq(struct ib_device *dev, void *private,
 				NULL);
 }
 
+struct ib_cq *__ib_alloc_cq_any(struct ib_device *dev, void *private,
+				int nr_cqe, enum ib_poll_context poll_ctx,
+				const char *caller);
+
+/**
+ * ib_alloc_cq_any: Allocate kernel CQ
+ * @dev: The IB device
+ * @private: Private data attached to the CQE
+ * @nr_cqe: Number of CQEs in the CQ
+ * @poll_ctx: Context used for polling the CQ
+ */
+static inline struct ib_cq *ib_alloc_cq_any(struct ib_device *dev,
+					    void *private, int nr_cqe,
+					    enum ib_poll_context poll_ctx)
+{
+	return __ib_alloc_cq_any(dev, private, nr_cqe, poll_ctx,
+				 KBUILD_MODNAME);
+}
+
 /**
  * ib_free_cq_user - Free kernel/user CQ
  * @cq: The CQ to free