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SUNRPC: Make RTT measurement more precise (Send)

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Some RPC transports have more overhead in their send_request
callouts than others. For example, for RPC-over-RDMA:

- Marshaling an RPC often has to DMA map the RPC arguments

- Registration methods perform memory registration as part of
  marshaling

To capture just server and network latencies more precisely: when
sending a Call, capture the rq_xtime timestamp _after_ the transport
header has been marshaled.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever 2018-03-05 15:13:07 -05:00 committed by Anna Schumaker
parent 0b87a46b43
commit 78215759e2
3 changed files with 4 additions and 1 deletions
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1
net/sunrpc/xprt.c
View File

@ -1033,7 +1033,6 @@ void xprt_transmit(struct rpc_task *task)
return;
connect_cookie = xprt->connect_cookie;
req->rq_xtime = ktime_get();
status = xprt->ops->send_request(task);
trace_xprt_transmit(xprt, req->rq_xid, status);
if (status != 0) {

1
net/sunrpc/xprtrdma/transport.c
View File

@ -696,6 +696,7 @@ xprt_rdma_send_request(struct rpc_task *task)
/* Must suppress retransmit to maintain credits */
if (rqst->rq_connect_cookie == xprt->connect_cookie)
goto drop_connection;
rqst->rq_xtime = ktime_get();
__set_bit(RPCRDMA_REQ_F_PENDING, &req->rl_flags);
if (rpcrdma_ep_post(&r_xprt->rx_ia, &r_xprt->rx_ep, req))

3
net/sunrpc/xprtsock.c
View File

@ -527,6 +527,7 @@ static int xs_local_send_request(struct rpc_task *task)
xs_pktdump("packet data:",
req->rq_svec->iov_base, req->rq_svec->iov_len);
req->rq_xtime = ktime_get();
status = xs_sendpages(transport->sock, NULL, 0, xdr, req->rq_bytes_sent,
true, &sent);
dprintk("RPC: %s(%u) = %d\n",
@ -589,6 +590,7 @@ static int xs_udp_send_request(struct rpc_task *task)
if (!xprt_bound(xprt))
return -ENOTCONN;
req->rq_xtime = ktime_get();
status = xs_sendpages(transport->sock, xs_addr(xprt), xprt->addrlen,
xdr, req->rq_bytes_sent, true, &sent);
@ -678,6 +680,7 @@ static int xs_tcp_send_request(struct rpc_task *task)
/* Continue transmitting the packet/record. We must be careful
* to cope with writespace callbacks arriving _after_ we have
* called sendmsg(). */
req->rq_xtime = ktime_get();
while (1) {
sent = 0;
status = xs_sendpages(transport->sock, NULL, 0, xdr,