Commit da662979 authored by Yamin Friedman's avatar Yamin Friedman Committed by Jason Gunthorpe
Browse files

RDMA/core: Provide RDMA DIM support for ULPs 



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: default avatarYamin Friedman <yaminf@mellanox.com>
Reviewed-by: default avatarMax Gurtovoy <maxg@mellanox.com>
Reviewed-by: default avatarSagi Grimberg <sagi@grimberg.me>
Signed-off-by: default avatarSaeed Mahameed <saeedm@mellanox.com>
Signed-off-by: default avatarLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
parent f4915455

drivers/infiniband/core/cq.c

+45 −0
Original line number Diff line number Diff line
@@ -18,6 +18,40 @@ 
#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 = dim->priv;



	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->priv = 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)

{
@@ -78,6 +112,7 @@ static void ib_cq_completion_direct(struct ib_cq *cq, void *private) 
static int ib_poll_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);
@@ -87,6 +122,9 @@ static int ib_poll_handler(struct irq_poll *iop, int budget) 
			irq_poll_sched(&cq->iop);

	}



	if (dim)

		rdma_dim(dim, completed);



	return completed;

}
@@ -105,6 +143,8 @@ static void ib_cq_poll_work(struct work_struct *work) 
	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)
@@ -161,6 +201,8 @@ struct ib_cq *__ib_alloc_cq_user(struct ib_device *dev, void *private, 


	rdma_restrack_kadd(&cq->res);



	rdma_dim_init(cq);



	switch (cq->poll_ctx) {

	case IB_POLL_DIRECT:

		cq->comp_handler = ib_cq_completion_direct;
@@ -223,6 +265,9 @@ void ib_free_cq_user(struct ib_cq *cq, struct ib_udata *udata) 


	rdma_restrack_del(&cq->res);

	cq->device->ops.destroy_cq(cq, udata);

	if (cq->dim)

		cancel_work_sync(&cq->dim->work);

	kfree(cq->dim);

	kfree(cq->wc);

	kfree(cq);

}

include/rdma/ib_verbs.h

+4 −0
Original line number Diff line number Diff line
@@ -61,6 +61,7 @@ 
#include <linux/cgroup_rdma.h>

#include <linux/irqflags.h>

#include <linux/preempt.h>

#include <linux/dim.h>

#include <uapi/rdma/ib_user_verbs.h>

#include <rdma/rdma_counter.h>

#include <rdma/restrack.h>
@@ -1509,6 +1510,7 @@ struct ib_cq { 
		struct work_struct	work;

	};

	struct workqueue_struct *comp_wq;

	struct dim *dim;

	/*

	 * Implementation details of the RDMA core, don't use in drivers:

	 */
@@ -2576,6 +2578,8 @@ struct ib_device { 
	u16                          is_switch:1;

	/* Indicates kernel verbs support, should not be used in drivers */

	u16                          kverbs_provider:1;

	/* CQ adaptive moderation (RDMA DIM) */

	u16                          use_cq_dim:1;

	u8                           node_type;

	u8                           phys_port_cnt;

	struct ib_device_attr        attrs;

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