From 433b0a12953bc1dfcb52febb186136395a65aad0 Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Tue, 20 Nov 2018 15:44:00 +0100 Subject: libceph: use MSG_SENDPAGE_NOTLAST with ceph_tcp_sendpage() Prevent do_tcp_sendpages() from calling tcp_push() (at least) once per page. Instead, arrange for tcp_push() to be called (at least) once per data payload. This results in more MSS-sized packets and fewer packets overall (5-10% reduction in my tests with typical OSD request sizes). See commits 2f5338442425 ("tcp: allow splice() to build full TSO packets"), 35f9c09fe9c7 ("tcp: tcp_sendpages() should call tcp_push() once") and ae62ca7b0321 ("tcp: fix MSG_SENDPAGE_NOTLAST logic") for details. Here is an example of a packet size histogram for 128K OSD requests (MSS = 1448, top 5): Before: SIZE COUNT 1448 777700 952 127915 1200 39238 1219 9806 21 5675 After: SIZE COUNT 1448 897280 21 6201 1019 2797 643 2739 376 2479 We could do slightly better by explicitly corking the socket but it's not clear it's worth it. Signed-off-by: Ilya Dryomov --- net/ceph/messenger.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) (limited to 'net/ceph') diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index 21a743a3bd29..649faa626b35 100644 --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -560,12 +560,15 @@ static int ceph_tcp_sendmsg(struct socket *sock, struct kvec *iov, return r; } +/* + * @more: either or both of MSG_MORE and MSG_SENDPAGE_NOTLAST + */ static int ceph_tcp_sendpage(struct socket *sock, struct page *page, - int offset, size_t size, bool more) + int offset, size_t size, int more) { ssize_t (*sendpage)(struct socket *sock, struct page *page, int offset, size_t size, int flags); - int flags = MSG_DONTWAIT | MSG_NOSIGNAL | (more ? MSG_MORE : 0); + int flags = MSG_DONTWAIT | MSG_NOSIGNAL | more; int ret; /* @@ -1552,6 +1555,7 @@ static int write_partial_message_data(struct ceph_connection *con) struct ceph_msg *msg = con->out_msg; struct ceph_msg_data_cursor *cursor = &msg->cursor; bool do_datacrc = !ceph_test_opt(from_msgr(con->msgr), NOCRC); + int more = MSG_MORE | MSG_SENDPAGE_NOTLAST; u32 crc; dout("%s %p msg %p\n", __func__, con, msg); @@ -1580,8 +1584,10 @@ static int write_partial_message_data(struct ceph_connection *con) } page = ceph_msg_data_next(cursor, &page_offset, &length, NULL); + if (length == cursor->total_resid) + more = MSG_MORE; ret = ceph_tcp_sendpage(con->sock, page, page_offset, length, - true); + more); if (ret <= 0) { if (do_datacrc) msg->footer.data_crc = cpu_to_le32(crc); @@ -1611,13 +1617,16 @@ static int write_partial_message_data(struct ceph_connection *con) */ static int write_partial_skip(struct ceph_connection *con) { + int more = MSG_MORE | MSG_SENDPAGE_NOTLAST; int ret; dout("%s %p %d left\n", __func__, con, con->out_skip); while (con->out_skip > 0) { size_t size = min(con->out_skip, (int) PAGE_SIZE); - ret = ceph_tcp_sendpage(con->sock, zero_page, 0, size, true); + if (size == con->out_skip) + more = MSG_MORE; + ret = ceph_tcp_sendpage(con->sock, zero_page, 0, size, more); if (ret <= 0) goto out; con->out_skip -= ret; -- cgit v1.2.3-59-g8ed1b