From: David Teigland <teigland@redhat.com>
Date: Fri, 12 Nov 2010 16:51:28 -0500
Subject: [fs] dlm: use TCP_NODELAY
Message-id: <20101112165128.GB11037@redhat.com>
Patchwork-id: 29218
O-Subject: [RHEL5.6 PATCH] dlm: use TCP_NODELAY
Bugzilla: 604139
RH-Acked-by: Steven Whitehouse <swhiteho@redhat.com>
RH-Acked-by: Robert S Peterson <rpeterso@redhat.com>
RH-Acked-by: David S. Miller <davem@redhat.com>
RH-Acked-by: Neil Horman <nhorman@redhat.com>

bz 604139 (patch 1 of 2)

upstream: scheduled for 2.6.38

Nagling doesn't help and can sometimes hurt dlm comms.


diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index b802a0f..164ab41 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -885,6 +885,7 @@ static void tcp_connect_to_sock(struct connection *con)
 	struct sockaddr_storage saddr, src_addr;
 	int addr_len;
 	struct socket *sock = NULL;
+	int one = 1;
 
 	if (con->nodeid == 0) {
 		log_print("attempt to connect sock 0 foiled");
@@ -930,6 +931,11 @@ static void tcp_connect_to_sock(struct connection *con)
 	make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);
 
 	log_print("connecting to %d", con->nodeid);
+
+	/* Turn off Nagle's algorithm */
+	kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
+			  sizeof(one));
+
 	result =
 		sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
 				   O_NONBLOCK);
@@ -981,6 +987,10 @@ static struct socket *tcp_create_listen_sock(struct connection *con,
 		goto create_out;
 	}
 
+	/* Turn off Nagle's algorithm */
+	kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
+			  sizeof(one));
+
 	result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
 				   (char *)&one, sizeof(one));