Merge branch 'rds-perf'

Sowmini Varadhan says:

====================
RDS: RDS-TCP perf enhancements

A 3-part patchset that (a) improves current RDS-TCP perf
by 2X-3X and (b) refactors earlier robustness code for
better observability/scaling.

Patch 1 is an enhancment of earlier robustness fixes
that had used separate sockets for client and server endpoints to
resolve race conditions. It is possible to have an equivalent
solution that does not use 2 sockets. The benefit of a
single socket solution is that it results in more predictable
and observable behavior for the underlying TCP pipe of an
RDS connection

Patches 2 and 3 are simple, straightforward perf bug fixes
that align the RDS TCP socket with other parts of the kernel stack.

v2: fix kbuild-test-robot warnings, comments from  Sergei Shtylov
    and Santosh Shilimkar.
====================
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rds/connection.c

@@ -128,10 +128,7 @@ static struct rds_connection *__rds_conn_create(struct net *net,
 	struct rds_transport *loop_trans;
 	unsigned long flags;
 	int ret;
-	struct rds_transport *otrans = trans;
 
-	if (!is_outgoing && otrans->t_type == RDS_TRANS_TCP)
-		goto new_conn;
 	rcu_read_lock();
 	conn = rds_conn_lookup(net, head, laddr, faddr, trans);
 	if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
@@ -147,7 +144,6 @@ static struct rds_connection *__rds_conn_create(struct net *net,
 	if (conn)
 		goto out;
 
-new_conn:
 	conn = kmem_cache_zalloc(rds_conn_slab, gfp);
 	if (!conn) {
 		conn = ERR_PTR(-ENOMEM);
@@ -207,6 +203,7 @@ static struct rds_connection *__rds_conn_create(struct net *net,
 
 	atomic_set(&conn->c_state, RDS_CONN_DOWN);
 	conn->c_send_gen = 0;
+	conn->c_outgoing = (is_outgoing ? 1 : 0);
 	conn->c_reconnect_jiffies = 0;
 	INIT_DELAYED_WORK(&conn->c_send_w, rds_send_worker);
 	INIT_DELAYED_WORK(&conn->c_recv_w, rds_recv_worker);
@@ -243,22 +240,13 @@ static struct rds_connection *__rds_conn_create(struct net *net,
 		/* Creating normal conn */
 		struct rds_connection *found;
 
-		if (!is_outgoing && otrans->t_type == RDS_TRANS_TCP)
-			found = NULL;
-		else
-			found = rds_conn_lookup(net, head, laddr, faddr, trans);
+		found = rds_conn_lookup(net, head, laddr, faddr, trans);
 		if (found) {
 			trans->conn_free(conn->c_transport_data);
 			kmem_cache_free(rds_conn_slab, conn);
 			conn = found;
 		} else {
-			if ((is_outgoing && otrans->t_type == RDS_TRANS_TCP) ||
-			    (otrans->t_type != RDS_TRANS_TCP)) {
-				/* Only the active side should be added to
-				 * reconnect list for TCP.
-				 */
-				hlist_add_head_rcu(&conn->c_hash_node, head);
-			}
+			hlist_add_head_rcu(&conn->c_hash_node, head);
 			rds_cong_add_conn(conn);
 			rds_conn_count++;
 		}
@@ -337,7 +325,9 @@ void rds_conn_shutdown(struct rds_connection *conn)
 	rcu_read_lock();
 	if (!hlist_unhashed(&conn->c_hash_node)) {
 		rcu_read_unlock();
-		rds_queue_reconnect(conn);
+		if (conn->c_trans->t_type != RDS_TRANS_TCP ||
+		    conn->c_outgoing == 1)
+			rds_queue_reconnect(conn);
 	} else {
 		rcu_read_unlock();
 	}

net/rds/rds.h

@@ -86,7 +86,9 @@ struct rds_connection {
 	struct hlist_node	c_hash_node;
 	__be32			c_laddr;
 	__be32			c_faddr;
-	unsigned int		c_loopback:1;
+	unsigned int		c_loopback:1,
+				c_outgoing:1,
+				c_pad_to_32:30;
 	struct rds_connection	*c_passive;
 
 	struct rds_cong_map	*c_lcong;

net/rds/tcp.c

@@ -67,21 +67,13 @@ void rds_tcp_nonagle(struct socket *sock)
 	set_fs(oldfs);
 }
 
+/* All module specific customizations to the RDS-TCP socket should be done in
+ * rds_tcp_tune() and applied after socket creation. In general these
+ * customizations should be tunable via module_param()
+ */
 void rds_tcp_tune(struct socket *sock)
 {
-	struct sock *sk = sock->sk;
-
 	rds_tcp_nonagle(sock);
-
-	/*
-	 * We're trying to saturate gigabit with the default,
-	 * see svc_sock_setbufsize().
-	 */
-	lock_sock(sk);
-	sk->sk_sndbuf = RDS_TCP_DEFAULT_BUFSIZE;
-	sk->sk_rcvbuf = RDS_TCP_DEFAULT_BUFSIZE;
-	sk->sk_userlocks |= SOCK_SNDBUF_LOCK|SOCK_RCVBUF_LOCK;
-	release_sock(sk);
 }
 
 u32 rds_tcp_snd_nxt(struct rds_tcp_connection *tc)

net/rds/tcp_listen.c

@@ -110,28 +110,24 @@ int rds_tcp_accept_one(struct socket *sock)
 		goto out;
 	}
 	/* An incoming SYN request came in, and TCP just accepted it.
-	 * We always create a new conn for listen side of TCP, and do not
-	 * add it to the c_hash_list.
 	 *
 	 * If the client reboots, this conn will need to be cleaned up.
 	 * rds_tcp_state_change() will do that cleanup
 	 */
 	rs_tcp = (struct rds_tcp_connection *)conn->c_transport_data;
-	WARN_ON(!rs_tcp || rs_tcp->t_sock);
-
-	/*
-	 * see the comment above rds_queue_delayed_reconnect()
-	 */
-	if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_CONNECTING)) {
-		if (rds_conn_state(conn) == RDS_CONN_UP)
-			rds_tcp_stats_inc(s_tcp_listen_closed_stale);
-		else
-			rds_tcp_stats_inc(s_tcp_connect_raced);
-		rds_conn_drop(conn);
+	if (rs_tcp->t_sock &&
+	    ntohl(inet->inet_saddr) < ntohl(inet->inet_daddr)) {
+		struct sock *nsk = new_sock->sk;
+
+		nsk->sk_user_data = NULL;
+		nsk->sk_prot->disconnect(nsk, 0);
+		tcp_done(nsk);
+		new_sock = NULL;
 		ret = 0;
 		goto out;
 	}
 
+	rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_CONNECTING);
 	rds_tcp_set_callbacks(new_sock, conn);
 	rds_connect_complete(conn);
 	new_sock = NULL;

net/rds/tcp_send.c

@@ -83,6 +83,7 @@ int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,
 	struct rds_tcp_connection *tc = conn->c_transport_data;
 	int done = 0;
 	int ret = 0;
+	int more;
 
 	if (hdr_off == 0) {
 		/*
@@ -116,12 +117,15 @@ 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,
-						MSG_DONTWAIT|MSG_NOSIGNAL);
+						flags);
 		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);
@@ -134,6 +138,8 @@ 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: