On 02/28/2018 03:30 PM, Chuck Lever wrote:
> With FRWR, the client transport can perform memory registration and
> post a Send with just a single ib_post_send.
>
> This reduces contention between the send_request path and the Send
> Completion handlers, and reduces the overhead of registering a chunk
> that has multiple segments.
>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
> net/sunrpc/xprtrdma/fmr_ops.c | 11 ++++++++
> net/sunrpc/xprtrdma/frwr_ops.c | 51 +++++++++++++++++++++++++++------------
> net/sunrpc/xprtrdma/verbs.c | 3 +-
> net/sunrpc/xprtrdma/xprt_rdma.h | 2 ++
> 4 files changed, 49 insertions(+), 18 deletions(-)
>
> diff --git a/net/sunrpc/xprtrdma/fmr_ops.c b/net/sunrpc/xprtrdma/fmr_ops.c
> index 629e539..5cc68a8 100644
> --- a/net/sunrpc/xprtrdma/fmr_ops.c
> +++ b/net/sunrpc/xprtrdma/fmr_ops.c
> @@ -251,6 +251,16 @@ enum {
> return ERR_PTR(-EIO);
> }
>
> +/* Post Send WR containing the RPC Call message.
> + */
> +static int
> +fmr_op_send(struct rpcrdma_ia *ia, struct rpcrdma_req *req)
> +{
> + struct ib_send_wr *bad_wr;
> +
> + return ib_post_send(ia->ri_id->qp, &req->rl_sendctx->sc_wr, &bad_wr);
I wish there was a bad_wr null-check in ib_post_send() (or in the infiniband drivers) so you don't have to declare a variable that's never used again. Coordinating that might be more work than it's worth, though.
Anna
> +}
> +
> /* Invalidate all memory regions that were registered for "req".
> *
> * Sleeps until it is safe for the host CPU to access the
> @@ -305,6 +315,7 @@ enum {
>
> const struct rpcrdma_memreg_ops rpcrdma_fmr_memreg_ops = {
> .ro_map = fmr_op_map,
> + .ro_send = fmr_op_send,
> .ro_unmap_sync = fmr_op_unmap_sync,
> .ro_recover_mr = fmr_op_recover_mr,
> .ro_open = fmr_op_open,
> diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
> index e21781c..c5743a0 100644
> --- a/net/sunrpc/xprtrdma/frwr_ops.c
> +++ b/net/sunrpc/xprtrdma/frwr_ops.c
> @@ -357,8 +357,7 @@
> struct rpcrdma_mr *mr;
> struct ib_mr *ibmr;
> struct ib_reg_wr *reg_wr;
> - struct ib_send_wr *bad_wr;
> - int rc, i, n;
> + int i, n;
> u8 key;
>
> mr = NULL;
> @@ -407,22 +406,12 @@
> ib_update_fast_reg_key(ibmr, ++key);
>
> reg_wr = &frwr->fr_regwr;
> - reg_wr->wr.next = NULL;
> - reg_wr->wr.opcode = IB_WR_REG_MR;
> - frwr->fr_cqe.done = frwr_wc_fastreg;
> - reg_wr->wr.wr_cqe = &frwr->fr_cqe;
> - reg_wr->wr.num_sge = 0;
> - reg_wr->wr.send_flags = 0;
> reg_wr->mr = ibmr;
> reg_wr->key = ibmr->rkey;
> reg_wr->access = writing ?
> IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
> IB_ACCESS_REMOTE_READ;
>
> - rc = ib_post_send(ia->ri_id->qp, ®_wr->wr, &bad_wr);
> - if (rc)
> - goto out_senderr;
> -
> mr->mr_handle = ibmr->rkey;
> mr->mr_length = ibmr->length;
> mr->mr_offset = ibmr->iova;
> @@ -442,11 +431,40 @@
> frwr->fr_mr, n, mr->mr_nents);
> rpcrdma_mr_defer_recovery(mr);
> return ERR_PTR(-EIO);
> +}
>
> -out_senderr:
> - pr_err("rpcrdma: FRWR registration ib_post_send returned %i\n", rc);
> - rpcrdma_mr_defer_recovery(mr);
> - return ERR_PTR(-ENOTCONN);
> +/* Post Send WR containing the RPC Call message.
> + *
> + * For FRMR, chain any FastReg WRs to the Send WR. Only a
> + * single ib_post_send call is needed to register memory
> + * and then post the Send WR.
> + */
> +static int
> +frwr_op_send(struct rpcrdma_ia *ia, struct rpcrdma_req *req)
> +{
> + struct ib_send_wr *post_wr, *bad_wr;
> + struct rpcrdma_mr *mr;
> +
> + post_wr = &req->rl_sendctx->sc_wr;
> + list_for_each_entry(mr, &req->rl_registered, mr_list) {
> + struct rpcrdma_frwr *frwr;
> +
> + frwr = &mr->frwr;
> +
> + frwr->fr_cqe.done = frwr_wc_fastreg;
> + frwr->fr_regwr.wr.next = post_wr;
> + frwr->fr_regwr.wr.wr_cqe = &frwr->fr_cqe;
> + frwr->fr_regwr.wr.num_sge = 0;
> + frwr->fr_regwr.wr.opcode = IB_WR_REG_MR;
> + frwr->fr_regwr.wr.send_flags = 0;
> +
> + post_wr = &frwr->fr_regwr.wr;
> + }
> +
> + /* If ib_post_send fails, the next ->send_request for
> + * @req will queue these MWs for recovery.
> + */
> + return ib_post_send(ia->ri_id->qp, post_wr, &bad_wr);
> }
>
> /* Handle a remotely invalidated mr on the @mrs list
> @@ -561,6 +579,7 @@
>
> const struct rpcrdma_memreg_ops rpcrdma_frwr_memreg_ops = {
> .ro_map = frwr_op_map,
> + .ro_send = frwr_op_send,
> .ro_reminv = frwr_op_reminv,
> .ro_unmap_sync = frwr_op_unmap_sync,
> .ro_recover_mr = frwr_op_recover_mr,
> diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
> index ab86724..626fd30 100644
> --- a/net/sunrpc/xprtrdma/verbs.c
> +++ b/net/sunrpc/xprtrdma/verbs.c
> @@ -1535,7 +1535,6 @@ struct rpcrdma_regbuf *
> struct rpcrdma_req *req)
> {
> struct ib_send_wr *send_wr = &req->rl_sendctx->sc_wr;
> - struct ib_send_wr *send_wr_fail;
> int rc;
>
> if (req->rl_reply) {
> @@ -1554,7 +1553,7 @@ struct rpcrdma_regbuf *
> --ep->rep_send_count;
> }
>
> - rc = ib_post_send(ia->ri_id->qp, send_wr, &send_wr_fail);
> + rc = ia->ri_ops->ro_send(ia, req);
> trace_xprtrdma_post_send(req, rc);
> if (rc)
> return -ENOTCONN;
> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
> index 29ea0b4..3d3b423 100644
> --- a/net/sunrpc/xprtrdma/xprt_rdma.h
> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h
> @@ -472,6 +472,8 @@ struct rpcrdma_memreg_ops {
> (*ro_map)(struct rpcrdma_xprt *,
> struct rpcrdma_mr_seg *, int, bool,
> struct rpcrdma_mr **);
> + int (*ro_send)(struct rpcrdma_ia *ia,
> + struct rpcrdma_req *req);
> void (*ro_reminv)(struct rpcrdma_rep *rep,
> struct list_head *mrs);
> void (*ro_unmap_sync)(struct rpcrdma_xprt *,
>
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