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rds: ib: Remove two ib_modify_qp() calls 

For some HCAs, ib_modify_qp() is an expensive operation running
virtualized.

For both the active and passive side, the QP returned by the CM has the
state set to RTS, so no need for this excess RTS -> RTS transition. With
IB Core's ability to set the RNR Retry timer, we use this interface to
shave off another ib_modify_qp().

Fixes: ec16227e14 ("RDS/IB: Infiniband transport")
Link: https://lore.kernel.org/r/1617216194-12890-3-git-send-email-haakon.bugge@oracle.com
Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Håkon Bugge 2021-03-31 20:43:14 +02:00 committed by Jason Gunthorpe
parent 3aeffc46af
commit 5aa54bd28c
2 changed files with 2 additions and 34 deletions
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35
net/rds/ib_cm.c
View File

@ -67,31 +67,6 @@ static void rds_ib_set_flow_control(struct rds_connection *conn, u32 credits)
}
}
/*
* Tune RNR behavior. Without flow control, we use a rather
* low timeout, but not the absolute minimum - this should
* be tunable.
*
* We already set the RNR retry count to 7 (which is the
* smallest infinite number :-) above.
* If flow control is off, we want to change this back to 0
* so that we learn quickly when our credit accounting is
* buggy.
*
* Caller passes in a qp_attr pointer - don't waste stack spacv
* by allocation this twice.
*/
static void
rds_ib_tune_rnr(struct rds_ib_connection *ic, struct ib_qp_attr *attr)
{
int ret;
attr->min_rnr_timer = IB_RNR_TIMER_000_32;
ret = ib_modify_qp(ic->i_cm_id->qp, attr, IB_QP_MIN_RNR_TIMER);
if (ret)
printk(KERN_NOTICE "ib_modify_qp(IB_QP_MIN_RNR_TIMER): err=%d\n", -ret);
}
/*
* Connection established.
* We get here for both outgoing and incoming connection.
@ -100,7 +75,6 @@ void rds_ib_cm_connect_complete(struct rds_connection *conn, struct rdma_cm_even
{
struct rds_ib_connection *ic = conn->c_transport_data;
const union rds_ib_conn_priv *dp = NULL;
struct ib_qp_attr qp_attr;
__be64 ack_seq = 0;
__be32 credit = 0;
u8 major = 0;
@ -168,14 +142,6 @@ void rds_ib_cm_connect_complete(struct rds_connection *conn, struct rdma_cm_even
* the posted credit count. */
rds_ib_recv_refill(conn, 1, GFP_KERNEL);
/* Tune RNR behavior */
rds_ib_tune_rnr(ic, &qp_attr);
qp_attr.qp_state = IB_QPS_RTS;
err = ib_modify_qp(ic->i_cm_id->qp, &qp_attr, IB_QP_STATE);
if (err)
printk(KERN_NOTICE "ib_modify_qp(IB_QP_STATE, RTS): err=%d\n", err);
/* update ib_device with this local ipaddr */
err = rds_ib_update_ipaddr(ic->rds_ibdev, &conn->c_laddr);
if (err)
@ -947,6 +913,7 @@ int rds_ib_cm_handle_connect(struct rdma_cm_id *cm_id,
event->param.conn.responder_resources,
event->param.conn.initiator_depth, isv6);
rdma_set_min_rnr_timer(cm_id, IB_RNR_TIMER_000_32);
/* rdma_accept() calls rdma_reject() internally if it fails */
if (rdma_accept(cm_id, &conn_param))
rds_ib_conn_error(conn, "rdma_accept failed\n");

1
net/rds/rdma_transport.c
View File

@ -87,6 +87,7 @@ static int rds_rdma_cm_event_handler_cmn(struct rdma_cm_id *cm_id,
case RDMA_CM_EVENT_ADDR_RESOLVED:
rdma_set_service_type(cm_id, conn->c_tos);
rdma_set_min_rnr_timer(cm_id, IB_RNR_TIMER_000_32);
/* XXX do we need to clean up if this fails? */
ret = rdma_resolve_route(cm_id,
RDS_RDMA_RESOLVE_TIMEOUT_MS);