xprtrdma: Pre-allocate Work Requests for backchannel

Pre-allocate extra send and receive Work Requests needed to handle
backchannel receives and sends.

The transport doesn't know how many extra WRs to pre-allocate until
the xprt_setup_backchannel() call, but that's long after the WRs are
allocated during forechannel setup.

So, use a fixed value for now.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Tested-By: Devesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/net/sunrpc/xprtrdma/backchannel.c b/net/sunrpc/xprtrdma/backchannel.c
index 3d01b328f777a3befc23d07898c610c28bc337fd..3165ed639eecedb5721a62dde3a9a70a55f4779d 100644 (file)
--- a/net/sunrpc/xprtrdma/backchannel.c
+++ b/net/sunrpc/xprtrdma/backchannel.c
@@ -125,6 +125,9 @@ int xprt_rdma_bc_setup(struct rpc_xprt *xprt, unsigned int reqs)
         * Twice as many rpc_rqsts are prepared to ensure there is
         * always an rpc_rqst available as soon as a reply is sent.
         */
+       if (reqs > RPCRDMA_BACKWARD_WRS >> 1)
+               goto out_err;
+
        for (i = 0; i < (reqs << 1); i++) {
                rqst = kzalloc(sizeof(*rqst), GFP_KERNEL);
                if (!rqst) {
@@ -161,6 +164,7 @@ int xprt_rdma_bc_setup(struct rpc_xprt *xprt, unsigned int reqs)
 out_free:
        xprt_rdma_bc_destroy(xprt, reqs);
 
+out_err:
        pr_err("RPC:       %s: setup backchannel transport failed\n", __func__);
        return -ENOMEM;
 }

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 7f0ed30fdc84c529c5c6580cff17f72a18ef0ab0..93883ffb86e0d0e6244f33d1558d11ac0f1d134b 100644 (file)
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -568,6 +568,7 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
        struct ib_device_attr *devattr = &ia->ri_devattr;
        struct ib_cq *sendcq, *recvcq;
        struct ib_cq_init_attr cq_attr = {};
+       unsigned int max_qp_wr;
        int rc, err;
 
        if (devattr->max_sge < RPCRDMA_MAX_IOVS) {
@@ -576,18 +577,27 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
                return -ENOMEM;
        }
 
+       if (devattr->max_qp_wr <= RPCRDMA_BACKWARD_WRS) {
+               dprintk("RPC:       %s: insufficient wqe's available\n",
+                       __func__);
+               return -ENOMEM;
+       }
+       max_qp_wr = devattr->max_qp_wr - RPCRDMA_BACKWARD_WRS;
+
        /* check provider's send/recv wr limits */
-       if (cdata->max_requests > devattr->max_qp_wr)
-               cdata->max_requests = devattr->max_qp_wr;
+       if (cdata->max_requests > max_qp_wr)
+               cdata->max_requests = max_qp_wr;
 
        ep->rep_attr.event_handler = rpcrdma_qp_async_error_upcall;
        ep->rep_attr.qp_context = ep;
        ep->rep_attr.srq = NULL;
        ep->rep_attr.cap.max_send_wr = cdata->max_requests;
+       ep->rep_attr.cap.max_send_wr += RPCRDMA_BACKWARD_WRS;
        rc = ia->ri_ops->ro_open(ia, ep, cdata);
        if (rc)
                return rc;
        ep->rep_attr.cap.max_recv_wr = cdata->max_requests;
+       ep->rep_attr.cap.max_recv_wr += RPCRDMA_BACKWARD_WRS;
        ep->rep_attr.cap.max_send_sge = RPCRDMA_MAX_IOVS;
        ep->rep_attr.cap.max_recv_sge = 1;
        ep->rep_attr.cap.max_inline_data = 0;

diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 1eb86c79f4b9f374eec3688a4127806d7d6e33df..55d2660df56a270e835a92140b54da76c882f00c 100644 (file)
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -101,6 +101,16 @@ struct rpcrdma_ep {
  */
 #define RPCRDMA_IGNORE_COMPLETION      (0ULL)
 
+/* Pre-allocate extra Work Requests for handling backward receives
+ * and sends. This is a fixed value because the Work Queues are
+ * allocated when the forward channel is set up.
+ */
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+#define RPCRDMA_BACKWARD_WRS           (8)
+#else
+#define RPCRDMA_BACKWARD_WRS           (0)
+#endif
+
 /* Registered buffer -- registered kmalloc'd memory for RDMA SEND/RECV
  *
  * The below structure appears at the front of a large region of kmalloc'd