tcp: basic cubic implementation

Because the code is not optimized, newreno is still the default
congestion control algorithm.

Change-Id: I7061cc80c5a75fa8e8265901fae4ea2888e35173
Signed-off-by: Florin Coras <fcoras@cisco.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index 843b90d987e..46262978a83 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -30,6 +30,7 @@
 #define TCP_PAWS_IDLE 24 * 24 * 60 * 60 * THZ /**< 24 days */
 #define TCP_FIB_RECHECK_PERIOD	1 * THZ	/**< Recheck every 1s */
 #define TCP_MAX_OPTION_SPACE 40
+#define TCP_CC_DATA_SZ 20
 
 #define TCP_DUPACK_THRESHOLD 	3
 #define TCP_MAX_RX_FIFO_SIZE 	32 << 20
@@ -249,6 +250,7 @@ u8 *format_tcp_scoreboard (u8 * s, va_list * args);
 typedef enum _tcp_cc_algorithm_type
 {
   TCP_CC_NEWRENO,
+  TCP_CC_CUBIC,
 } tcp_cc_algorithm_type_e;
 
 typedef struct _tcp_cc_algorithm tcp_cc_algorithm_t;
@@ -262,6 +264,7 @@ typedef enum _tcp_cc_ack_t
 
 typedef struct _tcp_connection
 {
+  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
   transport_connection_t connection;  /**< Common transport data. First! */
 
   u8 state;			/**< TCP state as per tcp_state_t */
@@ -315,6 +318,7 @@ typedef struct _tcp_connection
   u32 tsecr_last_ack;	/**< Timestamp echoed to us in last healthy ACK */
   u32 snd_congestion;	/**< snd_una_max when congestion is detected */
   tcp_cc_algorithm_t *cc_algo;	/**< Congestion control algorithm */
+  u8 cc_data[TCP_CC_DATA_SZ];	/**< Congestion control algo private data */
 
   /* RTT and RTO */
   u32 rto;		/**< Retransmission timeout */
@@ -329,6 +333,7 @@ typedef struct _tcp_connection
   u32 limited_transmit;	/**< snd_nxt when limited transmit starts */
   u32 last_fib_check;	/**< Last time we checked fib route for peer */
   u32 sw_if_index;	/**< Interface for the connection */
+  u32 tx_fifo_size;	/**< Tx fifo size. Used to constrain cwnd */
 } tcp_connection_t;
 
 struct _tcp_cc_algorithm
@@ -460,6 +465,8 @@ typedef struct _tcp_main
 
   /** fault-injection */
   f64 buffer_fail_fraction;
+
+  u8 cc_algo;
 } tcp_main_t;
 
 extern tcp_main_t tcp_main;
@@ -648,6 +655,25 @@ tcp_initial_cwnd (const tcp_connection_t * tc)
     return 4 * tc->snd_mss;
 }
 
+/*
+ * Accumulate acked bytes for cwnd increase
+ *
+ * Once threshold bytes are accumulated, snd_mss bytes are added
+ * to the cwnd.
+ */
+always_inline void
+tcp_cwnd_accumulate (tcp_connection_t * tc, u32 thresh, u32 bytes)
+{
+  tc->cwnd_acc_bytes += bytes;
+  if (tc->cwnd_acc_bytes >= thresh)
+    {
+      u32 inc = tc->cwnd_acc_bytes / thresh;
+      tc->cwnd_acc_bytes -= inc * thresh;
+      tc->cwnd += inc * tc->snd_mss;
+      tc->cwnd = clib_min (tc->cwnd, tc->tx_fifo_size);
+    }
+}
+
 always_inline u32
 tcp_loss_wnd (const tcp_connection_t * tc)
 {
@@ -870,6 +896,14 @@ void tcp_cc_algo_register (tcp_cc_algorithm_type_e type,
 
 tcp_cc_algorithm_t *tcp_cc_algo_get (tcp_cc_algorithm_type_e type);
 
+static inline void *
+tcp_cc_data (tcp_connection_t * tc)
+{
+  return (void *) tc->cc_data;
+}
+
+void newreno_rcv_cong_ack (tcp_connection_t * tc, tcp_cc_ack_t ack_type);
+
 /**
  * Push TCP header to buffer
  *