Commit 1edd6a14 authored Sep 30, 2015 by Sowmini Varadhan Committed by David S. Miller Oct 05, 2015

RDS-TCP: Do not bloat sndbuf/rcvbuf in rds_tcp_tune



Using the value of RDS_TCP_DEFAULT_BUFSIZE (128K)
clobbers efficient use of TSO because it inflates the size_goal
that is computed in tcp_sendmsg/tcp_sendpage and skews packet
latency, and the default values for these parameters actually
results in significantly better performance.

In request-response tests using rds-stress with a packet size of
100K with 16 threads (test parameters -q 100000 -a 256 -t16 -d16)
between a single pair of IP addresses achieves a throughput of
6-8 Gbps. Without this patch, throughput maxes at 2-3 Gbps under
equivalent conditions on these platforms.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 3b20fc38

net/rds/tcp.c

+4 −12

Original line number	Diff line number	Diff line
		@@ -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)

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