Reduce flakiness in tcp_test.

Tests now use a MinRTO of 3s instead of default 200ms. This reduced flakiness in
a lot of the congestion control/recovery tests which were flaky due to
retransmit timer firing too early in case the test executors were overloaded.

This change also bumps some of the timeouts in tests which were too sensitive to
timer variations and reduces the number of slow start iterations which can
make the tests run for too long and also trigger retansmit timeouts etc if
the executor is overloaded.

PiperOrigin-RevId: 306562645

1 files changed, 16 insertions, 1 deletions

diff --git a/pkg/tcpip/transport/tcp/testing/context/context.go b/pkg/tcpip/transport/tcp/testing/context/context.go
index 431ab4e6b..7b1d72cf4 100644
--- a/pkg/tcpip/transport/tcp/testing/context/context.go
+++ b/pkg/tcpip/transport/tcp/testing/context/context.go
@@ -152,6 +152,13 @@ func New(t *testing.T, mtu uint32) *Context {
 		t.Fatalf("SetTransportProtocolOption failed: %v", err)
 	}
 
+	// Increase minimum RTO in tests to avoid test flakes due to early
+	// retransmit in case the test executors are overloaded and cause timers
+	// to fire earlier than expected.
+	if err := s.SetTransportProtocolOption(tcp.ProtocolNumber, tcpip.TCPMinRTOOption(3*time.Second)); err != nil {
+		t.Fatalf("failed to set stack-wide minRTO: %s", err)
+	}
+
 	// Some of the congestion control tests send up to 640 packets, we so
 	// set the channel size to 1000.
 	ep := channel.New(1000, mtu, "")
@@ -236,7 +243,7 @@ func (c *Context) CheckNoPacket(errMsg string) {
 func (c *Context) GetPacket() []byte {
 	c.t.Helper()
 
-	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
 	p, ok := c.linkEP.ReadContext(ctx)
 	if !ok {
@@ -417,6 +424,8 @@ func (c *Context) SendAckWithSACK(seq seqnum.Value, bytesReceived int, sackBlock
 // verifies that the packet packet payload of packet matches the slice
 // of data indicated by offset & size.
 func (c *Context) ReceiveAndCheckPacket(data []byte, offset, size int) {
+	c.t.Helper()
+
 	c.ReceiveAndCheckPacketWithOptions(data, offset, size, 0)
 }
 
@@ -425,6 +434,8 @@ func (c *Context) ReceiveAndCheckPacket(data []byte, offset, size int) {
 // data indicated by offset & size and skips optlen bytes in addition to the IP
 // TCP headers when comparing the data.
 func (c *Context) ReceiveAndCheckPacketWithOptions(data []byte, offset, size, optlen int) {
+	c.t.Helper()
+
 	b := c.GetPacket()
 	checker.IPv4(c.t, b,
 		checker.PayloadLen(size+header.TCPMinimumSize+optlen),
@@ -447,6 +458,8 @@ func (c *Context) ReceiveAndCheckPacketWithOptions(data []byte, offset, size, op
 // data indicated by offset & size. It returns true if a packet was received and
 // processed.
 func (c *Context) ReceiveNonBlockingAndCheckPacket(data []byte, offset, size int) bool {
+	c.t.Helper()
+
 	b := c.GetPacketNonBlocking()
 	if b == nil {
 		return false
@@ -570,6 +583,8 @@ func (c *Context) CreateConnected(iss seqnum.Value, rcvWnd seqnum.Size, epRcvBuf
 //
 // PreCondition: c.EP must already be created.
 func (c *Context) Connect(iss seqnum.Value, rcvWnd seqnum.Size, options []byte) {
+	c.t.Helper()
+
 	// Start connection attempt.
 	waitEntry, notifyCh := waiter.NewChannelEntry(nil)
 	c.WQ.EventRegister(&waitEntry, waiter.EventOut)