Enable TCP Receive buffer moderation in gonet and benchmark.

Fixes #1666

PiperOrigin-RevId: 314148384

benchmarks/tcp/tcp_benchmark.sh

@@ -94,6 +94,9 @@ while [ $# -gt 0 ]; do
     --cubic)
       netstack_opts="${netstack_opts} -cubic"
       ;;
+    --moderate-recv-buf)
+      netstack_opts="${netstack_opts} -moderate_recv_buf"
+      ;;
     --duration)
       shift
       [ "$#" -le 0 ] && echo "no duration provided" && exit 1
@@ -147,8 +150,9 @@ while [ $# -gt 0 ]; do
       echo " --client              use netstack as the client"
       echo " --ideal               reset all network emulation"
       echo " --server              use netstack as the server"
-      echo " --mtu                 set the mtu (bytes)"
+      echo " --mtu                 set the mtu (bytes)"      
       echo " --sack                enable SACK support"
+      echo " --moderate-recv-buf   enable TCP receive buffer auto-tuning"
       echo " --cubic               enable CUBIC congestion control for Netstack"
       echo " --duration            set the test duration (s)"
       echo " --latency             set the latency (ms)"

benchmarks/tcp/tcp_proxy.go

@@ -56,6 +56,7 @@ var (
 	mask               = flag.Int("mask", 8, "mask size for address")
 	iface              = flag.String("iface", "", "network interface name to bind for netstack")
 	sack               = flag.Bool("sack", false, "enable SACK support for netstack")
+	moderateRecvBuf    = flag.Bool("moderate_recv_buf", false, "enable TCP Receive Buffer Auto-tuning")
 	cubic              = flag.Bool("cubic", false, "enable use of CUBIC congestion control for netstack")
 	gso                = flag.Int("gso", 0, "GSO maximum size")
 	swgso              = flag.Bool("swgso", false, "software-level GSO")
@@ -231,6 +232,11 @@ func newNetstackImpl(mode string) (impl, error) {
 		return nil, fmt.Errorf("SetTransportProtocolOption for SACKEnabled failed: %v", err)
 	}
 
+	// Enable Receive Buffer Auto-Tuning.
+	if err := s.SetTransportProtocolOption(tcp.ProtocolNumber, tcpip.ModerateReceiveBufferOption(*moderateRecvBuf)); err != nil {
+		return nil, fmt.Errorf("SetTransportProtocolOption failed: %v", err)
+	}
+
 	// Set Congestion Control to cubic if requested.
 	if *cubic {
 		if err := s.SetTransportProtocolOption(tcp.ProtocolNumber, tcpip.CongestionControlOption("cubic")); err != nil {

pkg/tcpip/adapters/gonet/gonet.go

@@ -335,6 +335,11 @@ func (c *TCPConn) Read(b []byte) (int, error) {
 	deadline := c.readCancel()
 
 	numRead := 0
+	defer func() {
+		if numRead != 0 {
+			c.ep.ModerateRecvBuf(numRead)
+		}
+	}()
 	for numRead != len(b) {
 		if len(c.read) == 0 {
 			var err error