svcrdma: Estimate Send Queue depth properly

The rdma_rw API adjusts max_send_wr upwards during the
rdma_create_qp() call. If the ULP actually wants to take advantage
of these extra resources, it must increase the size of its send
completion queue (created before rdma_create_qp is called) and
increase its send queue accounting limit.

Use the new rdma_rw_mr_factor API to figure out the correct value
to use for the Send Queue and Send Completion Queue depths.

And, ensure that the chosen Send Queue depth for a newly created
transport does not overrun the QP WR limit of the underlying device.

Lastly, there's no longer a need to carry the Send Queue depth in
struct svcxprt_rdma, since the value is used only in the
svc_rdma_accept() path.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 13 insertions, 4 deletions

diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index cdb04f8a0c25..5caf8e722a11 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -51,6 +51,7 @@
 #include <linux/workqueue.h>
 #include <rdma/ib_verbs.h>
 #include <rdma/rdma_cm.h>
+#include <rdma/rw.h>
 #include <linux/sunrpc/svc_rdma.h>
 #include <linux/export.h>
 #include "xprt_rdma.h"
@@ -713,7 +714,7 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
         struct ib_qp_init_attr qp_attr;
         struct ib_device *dev;
         struct sockaddr *sap;
-        unsigned int i;
+        unsigned int i, ctxts;
         int ret = 0;
 
         listen_rdma = container_of(xprt, struct svcxprt_rdma, sc_xprt);
@@ -754,7 +755,14 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
                 newxprt->sc_max_bc_requests = 2;
         }
         newxprt->sc_fc_credits = cpu_to_be32(newxprt->sc_max_requests);
-        newxprt->sc_sq_depth = newxprt->sc_rq_depth;
+        ctxts = rdma_rw_mr_factor(dev, newxprt->sc_port_num, RPCSVC_MAXPAGES);
+        ctxts *= newxprt->sc_max_requests;
+        newxprt->sc_sq_depth = newxprt->sc_rq_depth + ctxts;
+        if (newxprt->sc_sq_depth > dev->attrs.max_qp_wr) {
+                pr_warn("svcrdma: reducing send depth to %d\n",
+                        dev->attrs.max_qp_wr);
+                newxprt->sc_sq_depth = dev->attrs.max_qp_wr;
+        }
         atomic_set(&newxprt->sc_sq_avail, newxprt->sc_sq_depth);
 
         if (!svc_rdma_prealloc_ctxts(newxprt))
@@ -789,8 +797,8 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
         qp_attr.event_handler = qp_event_handler;
         qp_attr.qp_context = &newxprt->sc_xprt;
         qp_attr.port_num = newxprt->sc_port_num;
-        qp_attr.cap.max_rdma_ctxs = newxprt->sc_max_requests;
-        qp_attr.cap.max_send_wr = newxprt->sc_sq_depth;
+        qp_attr.cap.max_rdma_ctxs = ctxts;
+        qp_attr.cap.max_send_wr = newxprt->sc_sq_depth - ctxts;
         qp_attr.cap.max_recv_wr = newxprt->sc_rq_depth;
         qp_attr.cap.max_send_sge = newxprt->sc_max_sge;
         qp_attr.cap.max_recv_sge = newxprt->sc_max_sge;
@@ -858,6 +866,7 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
         dprintk("    remote address  : %pIS:%u\n", sap, rpc_get_port(sap));
         dprintk("    max_sge         : %d\n", newxprt->sc_max_sge);
         dprintk("    sq_depth        : %d\n", newxprt->sc_sq_depth);
+        dprintk("    rdma_rw_ctxs    : %d\n", ctxts);
         dprintk("    max_requests    : %d\n", newxprt->sc_max_requests);
         dprintk("    ord             : %d\n", newxprt->sc_ord);