RDMA/cxgb3: Turn off RX coalescing for iWARP connections

commit bec658ff31453a5726b1c188674d587a5d40c482 upstream.

The HW by default has RX coalescing on.  For iWARP connections, this
causes a 100ms delay in connection establishement due to the ingress
MPA Start message being stalled in HW.  So explicitly turn RX
coalescing off when setting up iWARP connections.

This was causing very bad performance for NP64 gather operations using
Open MPI, due to the way it sets up connections on larger jobs.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/infiniband/hw/cxgb3/iwch_cm.c b/drivers/infiniband/hw/cxgb3/iwch_cm.c
index 4fef032962761062c23bdb206301cea1d51dad6d..025c3f8e8f314b5b0473fa16656bcd911908e85e 100644 (file)
--- a/drivers/infiniband/hw/cxgb3/iwch_cm.c
+++ b/drivers/infiniband/hw/cxgb3/iwch_cm.c
@@ -487,7 +487,8 @@ static int send_connect(struct iwch_ep *ep)
            V_MSS_IDX(mtu_idx) |
            V_L2T_IDX(ep->l2t->idx) | V_TX_CHANNEL(ep->l2t->smt_idx);
        opt0l = V_TOS((ep->tos >> 2) & M_TOS) | V_RCV_BUFSIZ(rcv_win>>10);
-       opt2 = V_FLAVORS_VALID(1) | V_CONG_CONTROL_FLAVOR(cong_flavor);
+       opt2 = F_RX_COALESCE_VALID | V_RX_COALESCE(0) | V_FLAVORS_VALID(1) |
+              V_CONG_CONTROL_FLAVOR(cong_flavor);
        skb->priority = CPL_PRIORITY_SETUP;
        set_arp_failure_handler(skb, act_open_req_arp_failure);
 
@@ -1304,7 +1305,8 @@ static void accept_cr(struct iwch_ep *ep, __be32 peer_ip, struct sk_buff *skb)
            V_MSS_IDX(mtu_idx) |
            V_L2T_IDX(ep->l2t->idx) | V_TX_CHANNEL(ep->l2t->smt_idx);
        opt0l = V_TOS((ep->tos >> 2) & M_TOS) | V_RCV_BUFSIZ(rcv_win>>10);
-       opt2 = V_FLAVORS_VALID(1) | V_CONG_CONTROL_FLAVOR(cong_flavor);
+       opt2 = F_RX_COALESCE_VALID | V_RX_COALESCE(0) | V_FLAVORS_VALID(1) |
+              V_CONG_CONTROL_FLAVOR(cong_flavor);
 
        rpl = cplhdr(skb);
        rpl->wr.wr_hi = htonl(V_WR_OP(FW_WROPCODE_FORWARD));