[for-next V2 10/10] RDMA/core: Provide RDMA DIM support for ULPs

[Saeed Mahameed <saeedm@mellanox.com>]

From: Yamin Friedman <yaminf@mellanox.com>

Added the interface in the infiniband driver that applies the rdma_dim
adaptive moderation. There is now a special function for allocating an
ib_cq that uses rdma_dim.

Performance improvement (ConnectX-5 100GbE, x86) running FIO benchmark over
NVMf between two equal end-hosts with 56 cores across a Mellanox switch
using null_blk device:

READS without DIM:
blk size | BW       | IOPS | 99th percentile latency  | 99.99th latency
512B     | 3.8GiB/s | 7.7M | 1401  usec               | 2442  usec
4k       | 7.0GiB/s | 1.8M | 4817  usec               | 6587  usec
64k      | 10.7GiB/s| 175k | 9896  usec               | 10028 usec

IO WRITES without DIM:
blk size | BW       | IOPS | 99th percentile latency  | 99.99th latency
512B     | 3.6GiB/s | 7.5M | 1434  usec               | 2474  usec
4k       | 6.3GiB/s | 1.6M | 938   usec               | 1221  usec
64k      | 10.7GiB/s| 175k | 8979  usec               | 12780 usec

IO READS with DIM:
blk size | BW       | IOPS | 99th percentile latency  | 99.99th latency
512B     | 4GiB/s   | 8.2M | 816    usec              | 889   usec
4k       | 10.1GiB/s| 2.65M| 3359   usec              | 5080  usec
64k      | 10.7GiB/s| 175k | 9896   usec              | 10028 usec

IO WRITES with DIM:
blk size | BW       | IOPS  | 99th percentile latency | 99.99th latency
512B     | 3.9GiB/s | 8.1M  | 799   usec              | 922   usec
4k       | 9.6GiB/s | 2.5M  | 717   usec              | 1004  usec
64k      | 10.7GiB/s| 176k  | 8586  usec              | 12256 usec

The rdma_dim algorithm was designed to measure the effectiveness of
moderation on the flow in a general way and thus should be appropriate
for all RDMA storage protocols.

rdma_dim is configured to be the default option based on performance
improvement seen after extensive tests.

Signed-off-by: Yamin Friedman <yaminf@mellanox.com>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
---
 drivers/infiniband/core/cq.c      | 71 ++++++++++++++++++++++++++++++-
 drivers/infiniband/hw/mlx5/main.c |  2 +
 2 files changed, 71 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/cq.c b/drivers/infiniband/core/cq.c
index a4c81992267c..d8a8c466d897 100644
--- a/drivers/infiniband/core/cq.c
+++ b/drivers/infiniband/core/cq.c
@@ -26,6 +26,40 @@
 #define IB_POLL_FLAGS \
 	(IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS)
 
+static void ib_cq_rdma_dim_work(struct work_struct *w)
+{
+	struct dim *dim = container_of(w, struct dim, work);
+	struct ib_cq *cq = (struct ib_cq *)dim->dim_owner;
+
+	u16 usec = rdma_dim_prof[dim->profile_ix].usec;
+	u16 comps = rdma_dim_prof[dim->profile_ix].comps;
+
+	dim->state = DIM_START_MEASURE;
+
+	cq->device->ops.modify_cq(cq, comps, usec);
+}
+
+static void rdma_dim_init(struct ib_cq *cq)
+{
+	struct dim *dim;
+
+	if (!cq->device->ops.modify_cq || !cq->device->use_cq_dim ||
+	    cq->poll_ctx == IB_POLL_DIRECT)
+		return;
+
+	dim = kzalloc(sizeof(struct dim), GFP_KERNEL);
+	if (!dim)
+		return;
+
+	dim->state = DIM_START_MEASURE;
+	dim->tune_state = DIM_GOING_RIGHT;
+	dim->profile_ix = RDMA_DIM_START_PROFILE;
+	dim->dim_owner = cq;
+	cq->dim = dim;
+
+	INIT_WORK(&dim->work, ib_cq_rdma_dim_work);
+}
+
 static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc *wcs,
 			   int batch)
 {
@@ -98,6 +132,24 @@ static int ib_poll_handler(struct irq_poll *iop, int budget)
 	return completed;
 }
 
+static int ib_poll_dim_handler(struct irq_poll *iop, int budget)
+{
+	struct ib_cq *cq = container_of(iop, struct ib_cq, iop);
+	struct dim *dim = cq->dim;
+	int completed;
+
+	completed = __ib_process_cq(cq, budget, cq->wc, IB_POLL_BATCH);
+	if (completed < budget) {
+		irq_poll_complete(&cq->iop);
+		if (ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
+			irq_poll_sched(&cq->iop);
+	}
+
+	rdma_dim(dim, completed);
+
+	return completed;
+}
+
 static void ib_cq_completion_softirq(struct ib_cq *cq, void *private)
 {
 	irq_poll_sched(&cq->iop);
@@ -105,14 +157,18 @@ static void ib_cq_completion_softirq(struct ib_cq *cq, void *private)
 
 static void ib_cq_poll_work(struct work_struct *work)
 {
-	struct ib_cq *cq = container_of(work, struct ib_cq, work);
+	struct ib_cq *cq = container_of(work, struct ib_cq,
+					work);
 	int completed;
 
 	completed = __ib_process_cq(cq, IB_POLL_BUDGET_WORKQUEUE, cq->wc,
 				    IB_POLL_BATCH);
+
 	if (completed >= IB_POLL_BUDGET_WORKQUEUE ||
 	    ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
 		queue_work(cq->comp_wq, &cq->work);
+	else if (cq->dim)
+		rdma_dim(cq->dim, completed);
 }
 
 static void ib_cq_completion_workqueue(struct ib_cq *cq, void *private)
@@ -166,6 +222,8 @@ struct ib_cq *__ib_alloc_cq_user(struct ib_device *dev, void *private,
 	rdma_restrack_set_task(&cq->res, caller);
 	rdma_restrack_kadd(&cq->res);
 
+	rdma_dim_init(cq);
+
 	switch (cq->poll_ctx) {
 	case IB_POLL_DIRECT:
 		cq->comp_handler = ib_cq_completion_direct;
@@ -173,7 +231,13 @@ struct ib_cq *__ib_alloc_cq_user(struct ib_device *dev, void *private,
 	case IB_POLL_SOFTIRQ:
 		cq->comp_handler = ib_cq_completion_softirq;
 
-		irq_poll_init(&cq->iop, IB_POLL_BUDGET_IRQ, ib_poll_handler);
+		if (cq->dim) {
+			irq_poll_init(&cq->iop, IB_POLL_BUDGET_IRQ,
+				      ib_poll_dim_handler);
+		} else
+			irq_poll_init(&cq->iop, IB_POLL_BUDGET_IRQ,
+				      ib_poll_handler);
+
 		ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
 		break;
 	case IB_POLL_WORKQUEUE:
@@ -226,6 +290,9 @@ void ib_free_cq_user(struct ib_cq *cq, struct ib_udata *udata)
 		WARN_ON_ONCE(1);
 	}
 
+	if (cq->dim)
+		cancel_work_sync(&cq->dim->work);
+	kfree(cq->dim);
 	kfree(cq->wc);
 	rdma_restrack_del(&cq->res);
 	ret = cq->device->ops.destroy_cq(cq, udata);
diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index abac70ad5c7c..b1b45dbe24a5 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -6305,6 +6305,8 @@ static int mlx5_ib_stage_caps_init(struct mlx5_ib_dev *dev)
 	     MLX5_CAP_GEN(dev->mdev, disable_local_lb_mc)))
 		mutex_init(&dev->lb.mutex);
 
+	dev->ib_dev.use_cq_dim = true;
+
 	return 0;
 }
 
-- 
2.21.0