From aee4b74a3f273b54d136132fedf575ec464f4134 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Tue, 3 Mar 2020 11:08:05 -0500 Subject: svcrdma: Fix double sync of transport header buffer Performance optimization: Avoid syncing the transport buffer twice when Reply buffer pull-up is necessary. Signed-off-by: Chuck Lever --- net/sunrpc/xprtrdma/svc_rdma_backchannel.c | 1 - net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 4 +- net/sunrpc/xprtrdma/svc_rdma_sendto.c | 64 ++++++++++++------------------ 3 files changed, 28 insertions(+), 41 deletions(-) (limited to 'net/sunrpc') diff --git a/net/sunrpc/xprtrdma/svc_rdma_backchannel.c b/net/sunrpc/xprtrdma/svc_rdma_backchannel.c index 9830748c58d2..46b59e91d34a 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_backchannel.c +++ b/net/sunrpc/xprtrdma/svc_rdma_backchannel.c @@ -191,7 +191,6 @@ rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst) *p++ = xdr_zero; *p++ = xdr_zero; *p = xdr_zero; - svc_rdma_sync_reply_hdr(rdma, ctxt, ctxt->sc_hdrbuf.len); #ifdef SVCRDMA_BACKCHANNEL_DEBUG pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer); diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c index e2c747b5f517..54469b72b25f 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -735,9 +735,9 @@ static void svc_rdma_send_error(struct svcxprt_rdma *xprt, trace_svcrdma_err_chunk(*rdma_argp); } - svc_rdma_sync_reply_hdr(xprt, ctxt, ctxt->sc_hdrbuf.len); - + ctxt->sc_send_wr.num_sge = 1; ctxt->sc_send_wr.opcode = IB_WR_SEND; + ctxt->sc_sges[0].length = ctxt->sc_hdrbuf.len; ret = svc_rdma_send(xprt, &ctxt->sc_send_wr); if (ret) goto put_ctxt; diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c index 9d3b9a7e954f..7b9853214769 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c +++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c @@ -301,6 +301,12 @@ int svc_rdma_send(struct svcxprt_rdma *rdma, struct ib_send_wr *wr) might_sleep(); + /* Sync the transport header buffer */ + ib_dma_sync_single_for_device(rdma->sc_pd->device, + wr->sg_list[0].addr, + wr->sg_list[0].length, + DMA_TO_DEVICE); + /* If the SQ is full, wait until an SQ entry is available */ while (1) { if ((atomic_dec_return(&rdma->sc_sq_avail) < 0)) { @@ -532,24 +538,6 @@ static int svc_rdma_dma_map_buf(struct svcxprt_rdma *rdma, offset_in_page(base), len); } -/** - * svc_rdma_sync_reply_hdr - DMA sync the transport header buffer - * @rdma: controlling transport - * @ctxt: send_ctxt for the Send WR - * @len: length of transport header - * - */ -void svc_rdma_sync_reply_hdr(struct svcxprt_rdma *rdma, - struct svc_rdma_send_ctxt *ctxt, - unsigned int len) -{ - ctxt->sc_sges[0].length = len; - ctxt->sc_send_wr.num_sge++; - ib_dma_sync_single_for_device(rdma->sc_pd->device, - ctxt->sc_sges[0].addr, len, - DMA_TO_DEVICE); -} - /** * svc_rdma_pull_up_needed - Determine whether to use pull-up * @rdma: controlling transport @@ -612,9 +600,7 @@ static int svc_rdma_pull_up_reply_msg(struct svcxprt_rdma *rdma, unsigned char *dst, *tailbase; unsigned int taillen; - dst = sctxt->sc_xprt_buf; - dst += sctxt->sc_sges[0].length; - + dst = sctxt->sc_xprt_buf + sctxt->sc_hdrbuf.len; memcpy(dst, xdr->head[0].iov_base, xdr->head[0].iov_len); dst += xdr->head[0].iov_len; @@ -650,11 +636,6 @@ static int svc_rdma_pull_up_reply_msg(struct svcxprt_rdma *rdma, memcpy(dst, tailbase, taillen); sctxt->sc_sges[0].length += xdr->len; - ib_dma_sync_single_for_device(rdma->sc_pd->device, - sctxt->sc_sges[0].addr, - sctxt->sc_sges[0].length, - DMA_TO_DEVICE); - return 0; } @@ -665,7 +646,7 @@ static int svc_rdma_pull_up_reply_msg(struct svcxprt_rdma *rdma, * @xdr: prepared xdr_buf containing RPC message * * Load the xdr_buf into the ctxt's sge array, and DMA map each - * element as it is added. + * element as it is added. The Send WR's num_sge field is set. * * Returns zero on success, or a negative errno on failure. */ @@ -681,6 +662,19 @@ int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma, u32 xdr_pad; int ret; + /* Set up the (persistently-mapped) transport header SGE. */ + sctxt->sc_send_wr.num_sge = 1; + sctxt->sc_sges[0].length = sctxt->sc_hdrbuf.len; + + /* If there is a Reply chunk, nothing follows the transport + * header, and we're done here. + */ + if (rctxt && rctxt->rc_reply_chunk) + return 0; + + /* For pull-up, svc_rdma_send() will sync the transport header. + * No additional DMA mapping is necessary. + */ if (svc_rdma_pull_up_needed(rdma, rctxt, xdr)) return svc_rdma_pull_up_reply_msg(rdma, sctxt, rctxt, xdr); @@ -782,12 +776,9 @@ static int svc_rdma_send_reply_msg(struct svcxprt_rdma *rdma, { int ret; - if (!rctxt->rc_reply_chunk) { - ret = svc_rdma_map_reply_msg(rdma, sctxt, rctxt, - &rqstp->rq_res); - if (ret < 0) - return ret; - } + ret = svc_rdma_map_reply_msg(rdma, sctxt, rctxt, &rqstp->rq_res); + if (ret < 0) + return ret; svc_rdma_save_io_pages(rqstp, sctxt); @@ -797,8 +788,6 @@ static int svc_rdma_send_reply_msg(struct svcxprt_rdma *rdma, } else { sctxt->sc_send_wr.opcode = IB_WR_SEND; } - dprintk("svcrdma: posting Send WR with %u sge(s)\n", - sctxt->sc_send_wr.num_sge); return svc_rdma_send(rdma, &sctxt->sc_send_wr); } @@ -832,11 +821,11 @@ static int svc_rdma_send_error_msg(struct svcxprt_rdma *rdma, *p = err_chunk; trace_svcrdma_err_chunk(*rdma_argp); - svc_rdma_sync_reply_hdr(rdma, ctxt, ctxt->sc_hdrbuf.len); - svc_rdma_save_io_pages(rqstp, ctxt); + ctxt->sc_send_wr.num_sge = 1; ctxt->sc_send_wr.opcode = IB_WR_SEND; + ctxt->sc_sges[0].length = ctxt->sc_hdrbuf.len; return svc_rdma_send(rdma, &ctxt->sc_send_wr); } @@ -921,7 +910,6 @@ int svc_rdma_sendto(struct svc_rqst *rqstp) goto err0; } - svc_rdma_sync_reply_hdr(rdma, sctxt, sctxt->sc_hdrbuf.len); ret = svc_rdma_send_reply_msg(rdma, sctxt, rctxt, rqstp); if (ret < 0) goto err1; -- cgit v1.2.3