[PATCH net-next v4 05/15] rds: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage
From: David Howells <dhowells@redhat.com>
Date: 2023-06-23 11:46:58
Also in:
linux-mm, linux-rdma, lkml
Subsystem:
networking [general], rds - reliable datagram sockets, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Allison Henderson, Linus Torvalds
When transmitting data, call down into TCP using a single sendmsg with
MSG_SPLICE_PAGES to indicate that content should be spliced.
To make this work, the data is assembled in a bio_vec array and attached to
a BVEC-type iterator.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Santosh Shilimkar <redacted>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-rdma@vger.kernel.org
cc: rds-devel@oss.oracle.com
cc: netdev@vger.kernel.org
---
Notes:
ver #4)
- Reduce change to only call sendmsg on a page at a time.
net/rds/tcp_send.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/net/rds/tcp_send.c b/net/rds/tcp_send.c
index 8c4d1d6e9249..7d284ac7e81a 100644
--- a/net/rds/tcp_send.c
+++ b/net/rds/tcp_send.c@@ -72,9 +72,10 @@ int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm, { struct rds_conn_path *cp = rm->m_inc.i_conn_path; struct rds_tcp_connection *tc = cp->cp_transport_data; + struct msghdr msg = {}; + struct bio_vec bvec; int done = 0; int ret = 0; - int more; if (hdr_off == 0) { /*
@@ -111,15 +112,17 @@ int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm, goto out; } - more = rm->data.op_nents > 1 ? (MSG_MORE | MSG_SENDPAGE_NOTLAST) : 0; while (sg < rm->data.op_nents) { - int flags = MSG_DONTWAIT | MSG_NOSIGNAL | more; - - ret = tc->t_sock->ops->sendpage(tc->t_sock, - sg_page(&rm->data.op_sg[sg]), - rm->data.op_sg[sg].offset + off, - rm->data.op_sg[sg].length - off, - flags); + msg.msg_flags = MSG_SPLICE_PAGES | MSG_DONTWAIT | MSG_NOSIGNAL; + if (sg + 1 < rm->data.op_nents) + msg.msg_flags |= MSG_MORE; + + bvec_set_page(&bvec, sg_page(&rm->data.op_sg[sg]), + rm->data.op_sg[sg].length - off, + rm->data.op_sg[sg].offset + off); + iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, + rm->data.op_sg[sg].length - off); + ret = sock_sendmsg(tc->t_sock, &msg); rdsdebug("tcp sendpage %p:%u:%u ret %d\n", (void *)sg_page(&rm->data.op_sg[sg]), rm->data.op_sg[sg].offset + off, rm->data.op_sg[sg].length - off, ret);
@@ -132,8 +135,6 @@ int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm, off = 0; sg++; } - if (sg == rm->data.op_nents - 1) - more = 0; } out: