Performance optimization: Avoid syncing the transport buffer twice
when Reply buffer pull-up is necessary.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
include/linux/sunrpc/svc_rdma.h | 3 -
net/sunrpc/xprtrdma/svc_rdma_backchannel.c | 1
net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 4 +-
net/sunrpc/xprtrdma/svc_rdma_sendto.c | 58 ++++++++++------------------
4 files changed, 22 insertions(+), 44 deletions(-)
diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index d001aac13c2f..a3fa5b4fa2e4 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -191,9 +191,6 @@ extern struct svc_rdma_send_ctxt *
extern void svc_rdma_send_ctxt_put(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *ctxt);
extern int svc_rdma_send(struct svcxprt_rdma *rdma, struct ib_send_wr *wr);
-extern void svc_rdma_sync_reply_hdr(struct svcxprt_rdma *rdma,
- struct svc_rdma_send_ctxt *ctxt,
- unsigned int len);
extern int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *sctxt,
const struct svc_rdma_recv_ctxt *rctxt,
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 447060dbd6fd..2fb1de40613c 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -737,9 +737,9 @@ 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 f557e1cc5694..9a7317bc54c9 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)) {
@@ -530,24 +536,6 @@ 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
@@ -610,9 +598,7 @@ 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;
@@ -648,11 +634,6 @@ 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;
}
@@ -663,7 +644,7 @@ 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.
*/
@@ -679,6 +660,13 @@ 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 (rctxt && rctxt->rc_reply_chunk)
+ return 0;
+
if (svc_rdma_pull_up_needed(rdma, rctxt, xdr))
return svc_rdma_pull_up_reply_msg(rdma, sctxt, rctxt, xdr);
@@ -780,12 +768,9 @@ 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);
@@ -795,8 +780,6 @@ 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);
}
@@ -830,11 +813,11 @@ 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);
}
@@ -919,7 +902,6 @@ 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;
