xprtrmda: Reduce lock contention in completion handlers

Skip the ib_poll_cq() after re-arming, if the provider knows there
are no additional items waiting. (Have a look at commit ed23a727 for
more details).

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index af2d097c221f..c7d5281063fd 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -192,8 +192,11 @@ rpcrdma_sendcq_upcall(struct ib_cq *cq, void *cq_context)
                 return;
         }
 
-        rc = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
-        if (rc) {
+        rc = ib_req_notify_cq(cq,
+                        IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
+        if (rc == 0)
+                return;
+        if (rc < 0) {
                 dprintk("RPC:       %s: ib_req_notify_cq failed: %i\n",
                         __func__, rc);
                 return;
@@ -272,8 +275,11 @@ rpcrdma_recvcq_upcall(struct ib_cq *cq, void *cq_context)
                 return;
         }
 
-        rc = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
-        if (rc) {
+        rc = ib_req_notify_cq(cq,
+                        IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
+        if (rc == 0)
+                return;
+        if (rc < 0) {
                 dprintk("RPC:       %s: ib_req_notify_cq failed: %i\n",
                         __func__, rc);
                 return;