xprtrdma: Remove logic that constructs RDMA_MSGP type calls
RDMA_MSGP type calls insert a zero pad in the middle of the RPC message to align the RPC request's data payload to the server's alignment preferences. A server can then "page flip" the payload into place to avoid a data copy in certain circumstances. However: 1. The client has to have a priori knowledge of the server's preferred alignment 2. Requests eligible for RDMA_MSGP are requests that are small enough to have been sent inline, and convey a data payload at the _end_ of the RPC message Today 1. is done with a sysctl, and is a global setting that is copied during mount. Linux does not support CCP to query the server's preferences (RFC 5666, Section 6). A small-ish NFSv3 WRITE might use RDMA_MSGP, but no NFSv4 compound fits bullet 2. Thus the Linux client currently leaves RDMA_MSGP disabled. The Linux server handles RDMA_MSGP, but does not use any special page flipping, so it confers no benefit. Clean up the marshaling code by removing the logic that constructs RDMA_MSGP type calls. This also reduces the maximum send iovec size from four to just two elements. /proc/sys/sunrpc/rdma_inline_write_padding is a kernel API, and thus is left in place. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Tested-by: Devesh Sharma <devesh.sharma@avagotech.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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@ -297,8 +297,7 @@ out:
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* pre-registered memory buffer for this request. For small amounts
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* of data, this is efficient. The cutoff value is tunable.
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*/
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static int
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rpcrdma_inline_pullup(struct rpc_rqst *rqst, int pad)
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static void rpcrdma_inline_pullup(struct rpc_rqst *rqst)
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{
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int i, npages, curlen;
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int copy_len;
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@ -310,16 +309,9 @@ rpcrdma_inline_pullup(struct rpc_rqst *rqst, int pad)
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destp = rqst->rq_svec[0].iov_base;
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curlen = rqst->rq_svec[0].iov_len;
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destp += curlen;
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/*
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* Do optional padding where it makes sense. Alignment of write
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* payload can help the server, if our setting is accurate.
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*/
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pad -= (curlen + 36/*sizeof(struct rpcrdma_msg_padded)*/);
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if (pad < 0 || rqst->rq_slen - curlen < RPCRDMA_INLINE_PAD_THRESH)
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pad = 0; /* don't pad this request */
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dprintk("RPC: %s: pad %d destp 0x%p len %d hdrlen %d\n",
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__func__, pad, destp, rqst->rq_slen, curlen);
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dprintk("RPC: %s: destp 0x%p len %d hdrlen %d\n",
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__func__, destp, rqst->rq_slen, curlen);
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copy_len = rqst->rq_snd_buf.page_len;
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@ -355,7 +347,6 @@ rpcrdma_inline_pullup(struct rpc_rqst *rqst, int pad)
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page_base = 0;
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}
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/* header now contains entire send message */
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return pad;
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}
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/*
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@ -380,7 +371,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
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struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
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struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
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char *base;
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size_t rpclen, padlen;
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size_t rpclen;
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ssize_t hdrlen;
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enum rpcrdma_chunktype rtype, wtype;
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struct rpcrdma_msg *headerp;
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@ -458,7 +449,6 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
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}
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hdrlen = RPCRDMA_HDRLEN_MIN;
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padlen = 0;
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/*
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* Pull up any extra send data into the preregistered buffer.
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@ -467,32 +457,14 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
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*/
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if (rtype == rpcrdma_noch) {
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padlen = rpcrdma_inline_pullup(rqst,
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RPCRDMA_INLINE_PAD_VALUE(rqst));
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rpcrdma_inline_pullup(rqst);
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if (padlen) {
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headerp->rm_type = rdma_msgp;
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headerp->rm_body.rm_padded.rm_align =
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cpu_to_be32(RPCRDMA_INLINE_PAD_VALUE(rqst));
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headerp->rm_body.rm_padded.rm_thresh =
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cpu_to_be32(RPCRDMA_INLINE_PAD_THRESH);
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headerp->rm_body.rm_padded.rm_pempty[0] = xdr_zero;
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headerp->rm_body.rm_padded.rm_pempty[1] = xdr_zero;
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headerp->rm_body.rm_padded.rm_pempty[2] = xdr_zero;
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hdrlen += 2 * sizeof(u32); /* extra words in padhdr */
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if (wtype != rpcrdma_noch) {
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dprintk("RPC: %s: invalid chunk list\n",
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__func__);
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return -EIO;
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}
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} else {
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headerp->rm_body.rm_nochunks.rm_empty[0] = xdr_zero;
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headerp->rm_body.rm_nochunks.rm_empty[1] = xdr_zero;
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headerp->rm_body.rm_nochunks.rm_empty[2] = xdr_zero;
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/* new length after pullup */
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rpclen = rqst->rq_svec[0].iov_len;
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/*
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* Currently we try to not actually use read inline.
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/* Currently we try to not actually use read inline.
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* Reply chunks have the desirable property that
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* they land, packed, directly in the target buffers
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* without headers, so they require no fixup. The
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@ -504,7 +476,6 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
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if (wtype == rpcrdma_noch)
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wtype = rpcrdma_replych;
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}
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}
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if (rtype != rpcrdma_noch) {
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hdrlen = rpcrdma_create_chunks(rqst, &rqst->rq_snd_buf,
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@ -518,9 +489,9 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
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if (hdrlen < 0)
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return hdrlen;
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dprintk("RPC: %s: %s: hdrlen %zd rpclen %zd padlen %zd"
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dprintk("RPC: %s: %s: hdrlen %zd rpclen %zd"
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" headerp 0x%p base 0x%p lkey 0x%x\n",
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__func__, transfertypes[wtype], hdrlen, rpclen, padlen,
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__func__, transfertypes[wtype], hdrlen, rpclen,
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headerp, base, rdmab_lkey(req->rl_rdmabuf));
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/*
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@ -539,21 +510,6 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
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req->rl_send_iov[1].lkey = rdmab_lkey(req->rl_sendbuf);
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req->rl_niovs = 2;
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if (padlen) {
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struct rpcrdma_ep *ep = &r_xprt->rx_ep;
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req->rl_send_iov[2].addr = rdmab_addr(ep->rep_padbuf);
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req->rl_send_iov[2].length = padlen;
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req->rl_send_iov[2].lkey = rdmab_lkey(ep->rep_padbuf);
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req->rl_send_iov[3].addr = req->rl_send_iov[1].addr + rpclen;
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req->rl_send_iov[3].length = rqst->rq_slen - rpclen;
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req->rl_send_iov[3].lkey = rdmab_lkey(req->rl_sendbuf);
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req->rl_niovs = 4;
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}
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return 0;
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}
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@ -605,6 +605,12 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
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struct ib_cq_init_attr cq_attr = {};
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int rc, err;
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if (devattr->max_sge < RPCRDMA_MAX_IOVS) {
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dprintk("RPC: %s: insufficient sge's available\n",
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__func__);
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return -ENOMEM;
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}
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/* check provider's send/recv wr limits */
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if (cdata->max_requests > devattr->max_qp_wr)
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cdata->max_requests = devattr->max_qp_wr;
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@ -617,23 +623,13 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
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if (rc)
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return rc;
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ep->rep_attr.cap.max_recv_wr = cdata->max_requests;
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ep->rep_attr.cap.max_send_sge = (cdata->padding ? 4 : 2);
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ep->rep_attr.cap.max_send_sge = RPCRDMA_MAX_IOVS;
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ep->rep_attr.cap.max_recv_sge = 1;
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ep->rep_attr.cap.max_inline_data = 0;
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ep->rep_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
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ep->rep_attr.qp_type = IB_QPT_RC;
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ep->rep_attr.port_num = ~0;
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if (cdata->padding) {
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ep->rep_padbuf = rpcrdma_alloc_regbuf(ia, cdata->padding,
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GFP_KERNEL);
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if (IS_ERR(ep->rep_padbuf)) {
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rc = PTR_ERR(ep->rep_padbuf);
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goto out0;
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}
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} else
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ep->rep_padbuf = NULL;
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dprintk("RPC: %s: requested max: dtos: send %d recv %d; "
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"iovs: send %d recv %d\n",
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__func__,
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@ -716,8 +712,6 @@ out2:
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dprintk("RPC: %s: ib_destroy_cq returned %i\n",
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__func__, err);
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out1:
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rpcrdma_free_regbuf(ia, ep->rep_padbuf);
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out0:
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if (ia->ri_dma_mr)
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ib_dereg_mr(ia->ri_dma_mr);
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return rc;
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@ -746,8 +740,6 @@ rpcrdma_ep_destroy(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
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ia->ri_id->qp = NULL;
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}
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rpcrdma_free_regbuf(ia, ep->rep_padbuf);
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rpcrdma_clean_cq(ep->rep_attr.recv_cq);
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rc = ib_destroy_cq(ep->rep_attr.recv_cq);
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if (rc)
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struct rpcrdma_ep *ep,
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struct rpcrdma_req *req)
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{
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struct ib_device *device = ia->ri_device;
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struct ib_send_wr send_wr, *send_wr_fail;
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struct rpcrdma_rep *rep = req->rl_reply;
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int rc;
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struct ib_sge *iov = req->rl_send_iov;
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int i, rc;
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if (rep) {
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rc = rpcrdma_ep_post_recv(ia, ep, rep);
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send_wr.next = NULL;
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send_wr.wr_id = RPCRDMA_IGNORE_COMPLETION;
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send_wr.sg_list = req->rl_send_iov;
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send_wr.sg_list = iov;
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send_wr.num_sge = req->rl_niovs;
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send_wr.opcode = IB_WR_SEND;
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if (send_wr.num_sge == 4) /* no need to sync any pad (constant) */
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ib_dma_sync_single_for_device(ia->ri_device,
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req->rl_send_iov[3].addr,
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req->rl_send_iov[3].length,
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DMA_TO_DEVICE);
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ib_dma_sync_single_for_device(ia->ri_device,
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req->rl_send_iov[1].addr,
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req->rl_send_iov[1].length,
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DMA_TO_DEVICE);
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ib_dma_sync_single_for_device(ia->ri_device,
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req->rl_send_iov[0].addr,
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req->rl_send_iov[0].length,
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DMA_TO_DEVICE);
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for (i = 0; i < send_wr.num_sge; i++)
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ib_dma_sync_single_for_device(device, iov[i].addr,
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iov[i].length, DMA_TO_DEVICE);
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dprintk("RPC: %s: posting %d s/g entries\n",
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__func__, send_wr.num_sge);
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if (DECR_CQCOUNT(ep) > 0)
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send_wr.send_flags = 0;
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@ -88,7 +88,6 @@ struct rpcrdma_ep {
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int rep_connected;
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struct ib_qp_init_attr rep_attr;
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wait_queue_head_t rep_connect_wait;
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struct rpcrdma_regbuf *rep_padbuf;
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struct rdma_conn_param rep_remote_cma;
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struct sockaddr_storage rep_remote_addr;
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struct delayed_work rep_connect_worker;
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char *mr_offset; /* kva if no page, else offset */
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};
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#define RPCRDMA_MAX_IOVS (2)
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struct rpcrdma_req {
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unsigned int rl_niovs; /* 0, 2 or 4 */
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unsigned int rl_nchunks; /* non-zero if chunks */
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unsigned int rl_connect_cookie; /* retry detection */
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struct rpcrdma_buffer *rl_buffer; /* home base for this structure */
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unsigned int rl_niovs;
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unsigned int rl_nchunks;
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unsigned int rl_connect_cookie;
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struct rpcrdma_buffer *rl_buffer;
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struct rpcrdma_rep *rl_reply;/* holder for reply buffer */
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struct ib_sge rl_send_iov[4]; /* for active requests */
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struct ib_sge rl_send_iov[RPCRDMA_MAX_IOVS];
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struct rpcrdma_regbuf *rl_rdmabuf;
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struct rpcrdma_regbuf *rl_sendbuf;
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struct rpcrdma_mr_seg rl_segments[RPCRDMA_MAX_SEGS];
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