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rds: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage

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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 <santosh.shilimkar@oracle.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: rds-devel@oss.oracle.com
Link: https://lore.kernel.org/r/20230623225513.2732256-6-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
David Howells 2023-06-23 23:55:02 +01:00 committed by Jakub Kicinski
parent fa094ccae1
commit 572efade27
1 changed files with 11 additions and 10 deletions
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21
net/rds/tcp_send.c
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@ -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;
msg.msg_flags = MSG_SPLICE_PAGES | MSG_DONTWAIT | MSG_NOSIGNAL;
if (sg + 1 < rm->data.op_nents)
msg.msg_flags |= MSG_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);
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: