Merge rsync://rsync.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6

Documentation/networking/ip-sysctl.txt

@@ -304,57 +304,6 @@ tcp_low_latency - BOOLEAN
 	changed would be a Beowulf compute cluster.
 	Default: 0
 
-tcp_westwood - BOOLEAN
-        Enable TCP Westwood+ congestion control algorithm.
-	TCP Westwood+ is a sender-side only modification of the TCP Reno 
-	protocol stack that optimizes the performance of TCP congestion 
-	control. It is based on end-to-end bandwidth estimation to set 
-	congestion window and slow start threshold after a congestion 
-	episode. Using this estimation, TCP Westwood+ adaptively sets a 
-	slow start threshold and a congestion window which takes into 
-	account the bandwidth used  at the time congestion is experienced. 
-	TCP Westwood+ significantly increases fairness wrt TCP Reno in 
-	wired networks and throughput over wireless links.   
-        Default: 0
-
-tcp_vegas_cong_avoid - BOOLEAN
-	Enable TCP Vegas congestion avoidance algorithm.
-	TCP Vegas is a sender-side only change to TCP that anticipates
-	the onset of congestion by estimating the bandwidth. TCP Vegas
-	adjusts the sending rate by modifying the congestion
-	window. TCP Vegas should provide less packet loss, but it is
-	not as aggressive as TCP Reno.
-	Default:0
-
-tcp_bic - BOOLEAN
-	Enable BIC TCP congestion control algorithm.
-	BIC-TCP is a sender-side only change that ensures a linear RTT
-	fairness under large windows while offering both scalability and
-	bounded TCP-friendliness. The protocol combines two schemes
-	called additive increase and binary search increase. When the
-	congestion window is large, additive increase with a large
-	increment ensures linear RTT fairness as well as good
-	scalability. Under small congestion windows, binary search
-	increase provides TCP friendliness.
-	Default: 0
-
-tcp_bic_low_window - INTEGER
-	Sets the threshold window (in packets) where BIC TCP starts to
-	adjust the congestion window. Below this threshold BIC TCP behaves
-	the same as the default TCP Reno. 
-	Default: 14
-
-tcp_bic_fast_convergence - BOOLEAN
-	Forces BIC TCP to more quickly respond to changes in congestion
-	window. Allows two flows sharing the same connection to converge
-	more rapidly.
-	Default: 1
-
-tcp_default_win_scale - INTEGER
-	Sets the minimum window scale TCP will negotiate for on all
-	conections.
-	Default: 7
-
 tcp_tso_win_divisor - INTEGER
        This allows control over what percentage of the congestion window
        can be consumed by a single TSO frame.
@@ -368,6 +317,11 @@ tcp_frto - BOOLEAN
 	where packet loss is typically due to random radio interference
 	rather than intermediate router congestion.
 
+tcp_congestion_control - STRING
+	Set the congestion control algorithm to be used for new
+	connections. The algorithm "reno" is always available, but
+	additional choices may be available based on kernel configuration.
+
 somaxconn - INTEGER
 	Limit of socket listen() backlog, known in userspace as SOMAXCONN.
 	Defaults to 128.  See also tcp_max_syn_backlog for additional tuning

Documentation/networking/tcp.txt

-How the new TCP output machine [nyi] works.
+TCP protocol
+============
+
+Last updated: 21 June 2005
+
+Contents
+========
+
+- Congestion control
+- How the new TCP output machine [nyi] works
+
+Congestion control
+==================
+
+The following variables are used in the tcp_sock for congestion control:
+snd_cwnd		The size of the congestion window
+snd_ssthresh		Slow start threshold. We are in slow start if
+			snd_cwnd is less than this.
+snd_cwnd_cnt		A counter used to slow down the rate of increase
+			once we exceed slow start threshold.
+snd_cwnd_clamp		This is the maximum size that snd_cwnd can grow to.
+snd_cwnd_stamp		Timestamp for when congestion window last validated.
+snd_cwnd_used		Used as a highwater mark for how much of the
+			congestion window is in use. It is used to adjust
+			snd_cwnd down when the link is limited by the
+			application rather than the network.
+
+As of 2.6.13, Linux supports pluggable congestion control algorithms.
+A congestion control mechanism can be registered through functions in
+tcp_cong.c. The functions used by the congestion control mechanism are
+registered via passing a tcp_congestion_ops struct to
+tcp_register_congestion_control. As a minimum name, ssthresh,
+cong_avoid, min_cwnd must be valid.
 
+Private data for a congestion control mechanism is stored in tp->ca_priv.
+tcp_ca(tp) returns a pointer to this space.  This is preallocated space - it
+is important to check the size of your private data will fit this space, or
+alternatively space could be allocated elsewhere and a pointer to it could
+be stored here.
+
+There are three kinds of congestion control algorithms currently: The
+simplest ones are derived from TCP reno (highspeed, scalable) and just
+provide an alternative the congestion window calculation. More complex
+ones like BIC try to look at other events to provide better
+heuristics.  There are also round trip time based algorithms like
+Vegas and Westwood+.
+
+Good TCP congestion control is a complex problem because the algorithm
+needs to maintain fairness and performance. Please review current
+research and RFC's before developing new modules.
+
+The method that is used to determine which congestion control mechanism is
+determined by the setting of the sysctl net.ipv4.tcp_congestion_control.
+The default congestion control will be the last one registered (LIFO);
+so if you built everything as modules. the default will be reno. If you
+build with the default's from Kconfig, then BIC will be builtin (not a module)
+and it will end up the default.
+
+If you really want a particular default value then you will need
+to set it with the sysctl.  If you use a sysctl, the module will be autoloaded
+if needed and you will get the expected protocol. If you ask for an
+unknown congestion method, then the sysctl attempt will fail.
+
+If you remove a tcp congestion control module, then you will get the next
+available one. Since reno can not be built as a module, and can not be
+deleted, it will always be available.
+
+How the new TCP output machine [nyi] works.
+===========================================
 
 Data is kept on a single queue. The skb->users flag tells us if the frame is
 one that has been queued already. To add a frame we throw it on the end. Ack

include/linux/sysctl.h

@@ -333,21 +333,14 @@ enum
 	NET_TCP_FRTO=92,
 	NET_TCP_LOW_LATENCY=93,
 	NET_IPV4_IPFRAG_SECRET_INTERVAL=94,
-	NET_TCP_WESTWOOD=95,
 	NET_IPV4_IGMP_MAX_MSF=96,
 	NET_TCP_NO_METRICS_SAVE=97,
-	NET_TCP_VEGAS=98,
-	NET_TCP_VEGAS_ALPHA=99,
-	NET_TCP_VEGAS_BETA=100,
-	NET_TCP_VEGAS_GAMMA=101,
- 	NET_TCP_BIC=102,
- 	NET_TCP_BIC_FAST_CONVERGENCE=103,
-	NET_TCP_BIC_LOW_WINDOW=104,
 	NET_TCP_DEFAULT_WIN_SCALE=105,
 	NET_TCP_MODERATE_RCVBUF=106,
 	NET_TCP_TSO_WIN_DIVISOR=107,
 	NET_TCP_BIC_BETA=108,
 	NET_IPV4_ICMP_ERRORS_USE_INBOUND_IFADDR=109,
+	NET_TCP_CONG_CONTROL=110,
 };
 
 enum {

include/linux/tcp.h

@@ -203,13 +203,6 @@ struct tcp_sack_block {
 	__u32	end_seq;
 };
 
-enum tcp_congestion_algo {
-	TCP_RENO=0,
-	TCP_VEGAS,
-	TCP_WESTWOOD,
-	TCP_BIC,
-};
-
 struct tcp_options_received {
 /*	PAWS/RTTM data	*/
 	long	ts_recent_stamp;/* Time we stored ts_recent (for aging) */
@@ -305,7 +298,7 @@ struct tcp_sock {
 	__u8	reordering;	/* Packet reordering metric.		*/
 	__u8	frto_counter;	/* Number of new acks after RTO */
 
-	__u8	adv_cong;	/* Using Vegas, Westwood, or BIC */
+	__u8	unused;
 	__u8	defer_accept;	/* User waits for some data after accept() */
 
 /* RTT measurement */
@@ -401,37 +394,10 @@ struct tcp_sock {
 		__u32	time;
 	} rcvq_space;
 
-/* TCP Westwood structure */
-        struct {
-                __u32    bw_ns_est;        /* first bandwidth estimation..not too smoothed 8) */
-                __u32    bw_est;           /* bandwidth estimate */
-                __u32    rtt_win_sx;       /* here starts a new evaluation... */
-                __u32    bk;
-                __u32    snd_una;          /* used for evaluating the number of acked bytes */
-                __u32    cumul_ack;
-                __u32    accounted;
-                __u32    rtt;
-                __u32    rtt_min;          /* minimum observed RTT */
-        } westwood;
-
-/* Vegas variables */
-	struct {
-		__u32	beg_snd_nxt;	/* right edge during last RTT */
-		__u32	beg_snd_una;	/* left edge  during last RTT */
-		__u32	beg_snd_cwnd;	/* saves the size of the cwnd */
-		__u8	doing_vegas_now;/* if true, do vegas for this RTT */
-		__u16	cntRTT;		/* # of RTTs measured within last RTT */
-		__u32	minRTT;		/* min of RTTs measured within last RTT (in usec) */
-		__u32	baseRTT;	/* the min of all Vegas RTT measurements seen (in usec) */
-	} vegas;
-
-	/* BI TCP Parameters */
-	struct {
-		__u32	cnt;		/* increase cwnd by 1 after this number of ACKs */
-		__u32 	last_max_cwnd;	/* last maximium snd_cwnd */
-		__u32	last_cwnd;	/* the last snd_cwnd */
-		__u32   last_stamp;     /* time when updated last_cwnd */
-	} bictcp;
+	/* Pluggable TCP congestion control hook */
+	struct tcp_congestion_ops *ca_ops;
+	u32	ca_priv[16];
+#define TCP_CA_PRIV_SIZE	(16*sizeof(u32))
 };
 
 static inline struct tcp_sock *tcp_sk(const struct sock *sk)
@@ -439,6 +405,11 @@ static inline struct tcp_sock *tcp_sk(const struct sock *sk)
 	return (struct tcp_sock *)sk;
 }
 
+static inline void *tcp_ca(const struct tcp_sock *tp)
+{
+	return (void *) tp->ca_priv;
+}
+
 #endif
 
 #endif	/* _LINUX_TCP_H */

include/linux/tcp_diag.h

@@ -99,9 +99,10 @@ enum
 	TCPDIAG_MEMINFO,
 	TCPDIAG_INFO,
 	TCPDIAG_VEGASINFO,
+	TCPDIAG_CONG,
 };
 
-#define TCPDIAG_MAX TCPDIAG_VEGASINFO
+#define TCPDIAG_MAX TCPDIAG_CONG
 
 
 /* TCPDIAG_MEM */
@@ -123,5 +124,4 @@ struct tcpvegas_info {
 	__u32	tcpv_minrtt;
 };
 
-
 #endif /* _TCP_DIAG_H_ */

include/net/tcp.h

@@ -505,25 +505,6 @@ static __inline__ int tcp_sk_listen_hashfn(struct sock *sk)
 #else
 # define TCP_TW_RECYCLE_TICK (12+2-TCP_TW_RECYCLE_SLOTS_LOG)
 #endif
-
-#define BICTCP_BETA_SCALE    1024	/* Scale factor beta calculation
-					 * max_cwnd = snd_cwnd * beta
-					 */
-#define BICTCP_MAX_INCREMENT 32		/*
-					 * Limit on the amount of
-					 * increment allowed during
-					 * binary search.
-					 */
-#define BICTCP_FUNC_OF_MIN_INCR 11	/*
-					 * log(B/Smin)/log(B/(B-1))+1,
-					 * Smin:min increment
-					 * B:log factor
-					 */
-#define BICTCP_B		4	 /*
-					  * In binary search,
-					  * go to point (max+min)/N
-					  */
-
 /*
  *	TCP option
  */
@@ -596,16 +577,7 @@ extern int sysctl_tcp_adv_win_scale;
 extern int sysctl_tcp_tw_reuse;
 extern int sysctl_tcp_frto;
 extern int sysctl_tcp_low_latency;
-extern int sysctl_tcp_westwood;
-extern int sysctl_tcp_vegas_cong_avoid;
-extern int sysctl_tcp_vegas_alpha;
-extern int sysctl_tcp_vegas_beta;
-extern int sysctl_tcp_vegas_gamma;
 extern int sysctl_tcp_nometrics_save;
-extern int sysctl_tcp_bic;
-extern int sysctl_tcp_bic_fast_convergence;
-extern int sysctl_tcp_bic_low_window;
-extern int sysctl_tcp_bic_beta;
 extern int sysctl_tcp_moderate_rcvbuf;
 extern int sysctl_tcp_tso_win_divisor;
 
@@ -1136,6 +1108,80 @@ static inline void tcp_packets_out_dec(struct tcp_sock *tp,
 	tp->packets_out -= tcp_skb_pcount(skb);
 }
 
+/* Events passed to congestion control interface */
+enum tcp_ca_event {
+	CA_EVENT_TX_START,	/* first transmit when no packets in flight */
+	CA_EVENT_CWND_RESTART,	/* congestion window restart */
+	CA_EVENT_COMPLETE_CWR,	/* end of congestion recovery */
+	CA_EVENT_FRTO,		/* fast recovery timeout */
+	CA_EVENT_LOSS,		/* loss timeout */
+	CA_EVENT_FAST_ACK,	/* in sequence ack */
+	CA_EVENT_SLOW_ACK,	/* other ack */
+};
+
+/*
+ * Interface for adding new TCP congestion control handlers
+ */
+#define TCP_CA_NAME_MAX	16
+struct tcp_congestion_ops {
+	struct list_head	list;
+
+	/* initialize private data (optional) */
+	void (*init)(struct tcp_sock *tp);
+	/* cleanup private data  (optional) */
+	void (*release)(struct tcp_sock *tp);
+
+	/* return slow start threshold (required) */
+	u32 (*ssthresh)(struct tcp_sock *tp);
+	/* lower bound for congestion window (optional) */
+	u32 (*min_cwnd)(struct tcp_sock *tp);
+	/* do new cwnd calculation (required) */
+	void (*cong_avoid)(struct tcp_sock *tp, u32 ack,
+			   u32 rtt, u32 in_flight, int good_ack);
+	/* round trip time sample per acked packet (optional) */
+	void (*rtt_sample)(struct tcp_sock *tp, u32 usrtt);
+	/* call before changing ca_state (optional) */
+	void (*set_state)(struct tcp_sock *tp, u8 new_state);
+	/* call when cwnd event occurs (optional) */
+	void (*cwnd_event)(struct tcp_sock *tp, enum tcp_ca_event ev);
+	/* new value of cwnd after loss (optional) */
+	u32  (*undo_cwnd)(struct tcp_sock *tp);
+	/* hook for packet ack accounting (optional) */
+	void (*pkts_acked)(struct tcp_sock *tp, u32 num_acked);
+	/* get info for tcp_diag (optional) */
+	void (*get_info)(struct tcp_sock *tp, u32 ext, struct sk_buff *skb);
+
+	char 		name[TCP_CA_NAME_MAX];
+	struct module 	*owner;
+};
+
+extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
+extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
+
+extern void tcp_init_congestion_control(struct tcp_sock *tp);
+extern void tcp_cleanup_congestion_control(struct tcp_sock *tp);
+extern int tcp_set_default_congestion_control(const char *name);
+extern void tcp_get_default_congestion_control(char *name);
+
+extern struct tcp_congestion_ops tcp_reno;
+extern u32 tcp_reno_ssthresh(struct tcp_sock *tp);
+extern void tcp_reno_cong_avoid(struct tcp_sock *tp, u32 ack,
+				u32 rtt, u32 in_flight, int flag);
+extern u32 tcp_reno_min_cwnd(struct tcp_sock *tp);
+
+static inline void tcp_set_ca_state(struct tcp_sock *tp, u8 ca_state)
+{
+	if (tp->ca_ops->set_state)
+		tp->ca_ops->set_state(tp, ca_state);
+	tp->ca_state = ca_state;
+}
+
+static inline void tcp_ca_event(struct tcp_sock *tp, enum tcp_ca_event event)
+{
+	if (tp->ca_ops->cwnd_event)
+		tp->ca_ops->cwnd_event(tp, event);
+}
+
 /* This determines how many packets are "in the network" to the best
  * of our knowledge.  In many cases it is conservative, but where
  * detailed information is available from the receiver (via SACK
@@ -1155,91 +1201,6 @@ static __inline__ unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
 	return (tp->packets_out - tp->left_out + tp->retrans_out);
 }
 
-/*
- * Which congestion algorithim is in use on the connection.
- */
-#define tcp_is_vegas(__tp)	((__tp)->adv_cong == TCP_VEGAS)
-#define tcp_is_westwood(__tp)	((__tp)->adv_cong == TCP_WESTWOOD)
-#define tcp_is_bic(__tp)	((__tp)->adv_cong == TCP_BIC)
-
-/* Recalculate snd_ssthresh, we want to set it to:
- *
- * Reno:
- * 	one half the current congestion window, but no
- *	less than two segments
- *
- * BIC:
- *	behave like Reno until low_window is reached,
- *	then increase congestion window slowly
- */
-static inline __u32 tcp_recalc_ssthresh(struct tcp_sock *tp)
-{
-	if (tcp_is_bic(tp)) {
-		if (sysctl_tcp_bic_fast_convergence &&
-		    tp->snd_cwnd < tp->bictcp.last_max_cwnd)
-			tp->bictcp.last_max_cwnd = (tp->snd_cwnd * 
-						    (BICTCP_BETA_SCALE
-						     + sysctl_tcp_bic_beta))
-				/ (2 * BICTCP_BETA_SCALE);
-		else
-			tp->bictcp.last_max_cwnd = tp->snd_cwnd;
-
-		if (tp->snd_cwnd > sysctl_tcp_bic_low_window)
-			return max((tp->snd_cwnd * sysctl_tcp_bic_beta)
-				   / BICTCP_BETA_SCALE, 2U);
-	}
-
-	return max(tp->snd_cwnd >> 1U, 2U);
-}
-
-/* Stop taking Vegas samples for now. */
-#define tcp_vegas_disable(__tp)	((__tp)->vegas.doing_vegas_now = 0)
-    
-static inline void tcp_vegas_enable(struct tcp_sock *tp)
-{
-	/* There are several situations when we must "re-start" Vegas:
-	 *
-	 *  o when a connection is established
-	 *  o after an RTO
-	 *  o after fast recovery
-	 *  o when we send a packet and there is no outstanding
-	 *    unacknowledged data (restarting an idle connection)
-	 *
-	 * In these circumstances we cannot do a Vegas calculation at the
-	 * end of the first RTT, because any calculation we do is using
-	 * stale info -- both the saved cwnd and congestion feedback are
-	 * stale.
-	 *
-	 * Instead we must wait until the completion of an RTT during
-	 * which we actually receive ACKs.
-	 */
-    
-	/* Begin taking Vegas samples next time we send something. */
-	tp->vegas.doing_vegas_now = 1;
-     
-	/* Set the beginning of the next send window. */
-	tp->vegas.beg_snd_nxt = tp->snd_nxt;
-
-	tp->vegas.cntRTT = 0;
-	tp->vegas.minRTT = 0x7fffffff;
-}
-
-/* Should we be taking Vegas samples right now? */
-#define tcp_vegas_enabled(__tp)	((__tp)->vegas.doing_vegas_now)
-
-extern void tcp_ca_init(struct tcp_sock *tp);
-
-static inline void tcp_set_ca_state(struct tcp_sock *tp, u8 ca_state)
-{
-	if (tcp_is_vegas(tp)) {
-		if (ca_state == TCP_CA_Open) 
-			tcp_vegas_enable(tp);
-		else
-			tcp_vegas_disable(tp);
-	}
-	tp->ca_state = ca_state;
-}
-
 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
  * The exception is rate halving phase, when cwnd is decreasing towards
  * ssthresh.
@@ -1288,7 +1249,7 @@ static inline void tcp_cwnd_validate(struct sock *sk, struct tcp_sock *tp)
 static inline void __tcp_enter_cwr(struct tcp_sock *tp)
 {
 	tp->undo_marker = 0;
-	tp->snd_ssthresh = tcp_recalc_ssthresh(tp);
+	tp->snd_ssthresh = tp->ca_ops->ssthresh(tp);
 	tp->snd_cwnd = min(tp->snd_cwnd,
 			   tcp_packets_in_flight(tp) + 1U);
 	tp->snd_cwnd_cnt = 0;
@@ -1876,52 +1837,4 @@ struct tcp_iter_state {
 extern int tcp_proc_register(struct tcp_seq_afinfo *afinfo);
 extern void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo);
 
-/* TCP Westwood functions and constants */
-
-#define TCP_WESTWOOD_INIT_RTT  (20*HZ)           /* maybe too conservative?! */
-#define TCP_WESTWOOD_RTT_MIN   (HZ/20)           /* 50ms */
-
-static inline void tcp_westwood_update_rtt(struct tcp_sock *tp, __u32 rtt_seq)
-{
-        if (tcp_is_westwood(tp))
-                tp->westwood.rtt = rtt_seq;
-}
-
-static inline __u32 __tcp_westwood_bw_rttmin(const struct tcp_sock *tp)
-{
-        return max((tp->westwood.bw_est) * (tp->westwood.rtt_min) /
-		   (__u32) (tp->mss_cache_std),
-		   2U);
-}
-
-static inline __u32 tcp_westwood_bw_rttmin(const struct tcp_sock *tp)
-{
-	return tcp_is_westwood(tp) ? __tcp_westwood_bw_rttmin(tp) : 0;
-}
-
-static inline int tcp_westwood_ssthresh(struct tcp_sock *tp)
-{
-	__u32 ssthresh = 0;
-
-	if (tcp_is_westwood(tp)) {
-		ssthresh = __tcp_westwood_bw_rttmin(tp);
-		if (ssthresh)
-			tp->snd_ssthresh = ssthresh;  
-	}
-
-	return (ssthresh != 0);
-}
-
-static inline int tcp_westwood_cwnd(struct tcp_sock *tp)
-{
-	__u32 cwnd = 0;
-
-	if (tcp_is_westwood(tp)) {
-		cwnd = __tcp_westwood_bw_rttmin(tp);
-		if (cwnd)
-			tp->snd_cwnd = cwnd;
-	}
-
-	return (cwnd != 0);
-}
 #endif	/* _TCP_H */

net/ipv4/Kconfig

@@ -433,5 +433,95 @@ config IP_TCPDIAG
 config IP_TCPDIAG_IPV6
 	def_bool (IP_TCPDIAG=y && IPV6=y) || (IP_TCPDIAG=m && IPV6)
 
+# TCP Reno is builtin (required as fallback)
+menu "TCP congestion control"
+	depends on INET
+
+config TCP_CONG_BIC
+	tristate "Binary Increase Congestion (BIC) control"
+	depends on INET
+	default y
+	---help---
+	BIC-TCP is a sender-side only change that ensures a linear RTT
+	fairness under large windows while offering both scalability and
+	bounded TCP-friendliness. The protocol combines two schemes
+	called additive increase and binary search increase. When the
+	congestion window is large, additive increase with a large
+	increment ensures linear RTT fairness as well as good
+	scalability. Under small congestion windows, binary search
+	increase provides TCP friendliness.
+	See http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/
+
+config TCP_CONG_WESTWOOD
+	tristate "TCP Westwood+"
+	depends on INET
+	default m
+	---help---
+	TCP Westwood+ is a sender-side only modification of the TCP Reno
+	protocol stack that optimizes the performance of TCP congestion
+	control. It is based on end-to-end bandwidth estimation to set
+	congestion window and slow start threshold after a congestion
+	episode. Using this estimation, TCP Westwood+ adaptively sets a
+	slow start threshold and a congestion window which takes into
+	account the bandwidth used  at the time congestion is experienced.
+	TCP Westwood+ significantly increases fairness wrt TCP Reno in
+	wired networks and throughput over wireless links.
+
+config TCP_CONG_HTCP
+        tristate "H-TCP"
+	depends on INET
+        default m
+	---help---
+	H-TCP is a send-side only modifications of the TCP Reno
+	protocol stack that optimizes the performance of TCP
+	congestion control for high speed network links. It uses a
+	modeswitch to change the alpha and beta parameters of TCP Reno
+	based on network conditions and in a way so as to be fair with
+	other Reno and H-TCP flows.
+
+config TCP_CONG_HSTCP
+	tristate "High Speed TCP"
+	depends on INET && EXPERIMENTAL
+	default n
+	---help---
+	Sally Floyd's High Speed TCP (RFC 3649) congestion control.
+	A modification to TCP's congestion control mechanism for use
+	with large congestion windows. A table indicates how much to
+	increase the congestion window by when an ACK is received.
+ 	For more detail	see http://www.icir.org/floyd/hstcp.html
+
+config TCP_CONG_HYBLA
+	tristate "TCP-Hybla congestion control algorithm"
+	depends on INET && EXPERIMENTAL
+	default n
+	---help---
+	TCP-Hybla is a sender-side only change that eliminates penalization of
+	long-RTT, large-bandwidth connections, like when satellite legs are
+	involved, expecially when sharing a common bottleneck with normal
+	terrestrial connections.
+
+config TCP_CONG_VEGAS
+	tristate "TCP Vegas"
+	depends on INET && EXPERIMENTAL
+	default n
+	---help---
+	TCP Vegas is a sender-side only change to TCP that anticipates
+	the onset of congestion by estimating the bandwidth. TCP Vegas
+	adjusts the sending rate by modifying the congestion
+	window. TCP Vegas should provide less packet loss, but it is
+	not as aggressive as TCP Reno.
+
+config TCP_CONG_SCALABLE
+	tristate "Scalable TCP"
+	depends on INET && EXPERIMENTAL
+	default n
+	---help---
+	Scalable TCP is a sender-side only change to TCP which uses a
+	MIMD congestion control algorithm which has some nice scaling
+	properties, though is known to have fairness issues.
+	See http://www-lce.eng.cam.ac.uk/~ctk21/scalable/
+
+endmenu
+
 source "net/ipv4/ipvs/Kconfig"
 

net/ipv4/Makefile

@@ -5,7 +5,8 @@
 obj-y     := utils.o route.o inetpeer.o protocol.o \
 	     ip_input.o ip_fragment.o ip_forward.o ip_options.o \
 	     ip_output.o ip_sockglue.o \
-	     tcp.o tcp_input.o tcp_output.o tcp_timer.o tcp_ipv4.o tcp_minisocks.o \
+	     tcp.o tcp_input.o tcp_output.o tcp_timer.o tcp_ipv4.o \
+	     tcp_minisocks.o tcp_cong.o \
 	     datagram.o raw.o udp.o arp.o icmp.o devinet.o af_inet.o igmp.o \
 	     sysctl_net_ipv4.o fib_frontend.o fib_semantics.o
 
@@ -30,6 +31,13 @@ obj-$(CONFIG_NETFILTER)	+= netfilter/
 obj-$(CONFIG_IP_VS) += ipvs/
 obj-$(CONFIG_IP_TCPDIAG) += tcp_diag.o 
 obj-$(CONFIG_IP_ROUTE_MULTIPATH_CACHED) += multipath.o
+obj-$(CONFIG_TCP_CONG_BIC) += tcp_bic.o
+obj-$(CONFIG_TCP_CONG_WESTWOOD) += tcp_westwood.o
+obj-$(CONFIG_TCP_CONG_HSTCP) += tcp_highspeed.o
+obj-$(CONFIG_TCP_CONG_HYBLA) += tcp_hybla.o
+obj-$(CONFIG_TCP_CONG_HTCP) += tcp_htcp.o
+obj-$(CONFIG_TCP_CONG_VEGAS) += tcp_vegas.o
+obj-$(CONFIG_TCP_CONG_SCALABLE) += tcp_scalable.o
 
 obj-$(CONFIG_XFRM) += xfrm4_policy.o xfrm4_state.o xfrm4_input.o \
 		      xfrm4_output.o

net/ipv4/sysctl_net_ipv4.c

@@ -118,6 +118,45 @@ static int ipv4_sysctl_forward_strategy(ctl_table *table,
 	return 1;
 }
 
+static int proc_tcp_congestion_control(ctl_table *ctl, int write, struct file * filp,
+				       void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	char val[TCP_CA_NAME_MAX];
+	ctl_table tbl = {
+		.data = val,
+		.maxlen = TCP_CA_NAME_MAX,
+	};
+	int ret;
+
+	tcp_get_default_congestion_control(val);
+
+	ret = proc_dostring(&tbl, write, filp, buffer, lenp, ppos);
+	if (write && ret == 0)
+		ret = tcp_set_default_congestion_control(val);
+	return ret;
+}
+
+int sysctl_tcp_congestion_control(ctl_table *table, int __user *name, int nlen,
+				  void __user *oldval, size_t __user *oldlenp,
+				  void __user *newval, size_t newlen,
+				  void **context)
+{
+	char val[TCP_CA_NAME_MAX];
+	ctl_table tbl = {
+		.data = val,
+		.maxlen = TCP_CA_NAME_MAX,
+	};
+	int ret;
+
+	tcp_get_default_congestion_control(val);
+	ret = sysctl_string(&tbl, name, nlen, oldval, oldlenp, newval, newlen,
+			    context);
+	if (ret == 0 && newval && newlen)
+		ret = tcp_set_default_congestion_control(val);
+	return ret;
+}
+
+
 ctl_table ipv4_table[] = {
         {
 		.ctl_name	= NET_IPV4_TCP_TIMESTAMPS,
@@ -611,70 +650,6 @@ ctl_table ipv4_table[] = {
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec,
 	},
-	{
-		.ctl_name	= NET_TCP_WESTWOOD, 
-		.procname	= "tcp_westwood",
-		.data		= &sysctl_tcp_westwood,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= &proc_dointvec,
-	},
-	{
-		.ctl_name	= NET_TCP_VEGAS,
-		.procname	= "tcp_vegas_cong_avoid",
-		.data		= &sysctl_tcp_vegas_cong_avoid,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= &proc_dointvec,
-	},
-	{
-		.ctl_name	= NET_TCP_VEGAS_ALPHA,
-		.procname	= "tcp_vegas_alpha",
-		.data		= &sysctl_tcp_vegas_alpha,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= &proc_dointvec,
-	},
-	{
-		.ctl_name	= NET_TCP_VEGAS_BETA,
-		.procname	= "tcp_vegas_beta",
-		.data		= &sysctl_tcp_vegas_beta,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= &proc_dointvec,
-	},
-	{
-		.ctl_name	= NET_TCP_VEGAS_GAMMA,
-		.procname	= "tcp_vegas_gamma",
-		.data		= &sysctl_tcp_vegas_gamma,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= &proc_dointvec,
-	},
-	{
-		.ctl_name	= NET_TCP_BIC,
-		.procname	= "tcp_bic",
-		.data		= &sysctl_tcp_bic,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= &proc_dointvec,
-	},
-	{
-		.ctl_name	= NET_TCP_BIC_FAST_CONVERGENCE,
-		.procname	= "tcp_bic_fast_convergence",
-		.data		= &sysctl_tcp_bic_fast_convergence,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= &proc_dointvec,
-	},
-	{
-		.ctl_name	= NET_TCP_BIC_LOW_WINDOW,
-		.procname	= "tcp_bic_low_window",
-		.data		= &sysctl_tcp_bic_low_window,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= &proc_dointvec,
-	},
 	{
 		.ctl_name	= NET_TCP_MODERATE_RCVBUF,
 		.procname	= "tcp_moderate_rcvbuf",
@@ -692,13 +667,14 @@ ctl_table ipv4_table[] = {
 		.proc_handler	= &proc_dointvec,
 	},
 	{
-		.ctl_name	= NET_TCP_BIC_BETA,
-		.procname	= "tcp_bic_beta",
-		.data		= &sysctl_tcp_bic_beta,
-		.maxlen		= sizeof(int),
+		.ctl_name	= NET_TCP_CONG_CONTROL,
+		.procname	= "tcp_congestion_control",
 		.mode		= 0644,
-		.proc_handler	= &proc_dointvec,
+		.maxlen		= TCP_CA_NAME_MAX,
+		.proc_handler	= &proc_tcp_congestion_control,
+		.strategy	= &sysctl_tcp_congestion_control,
 	},
+
 	{ .ctl_name = 0 }
 };
 

net/ipv4/tcp.c

@@ -2333,6 +2333,8 @@ void __init tcp_init(void)
 	printk(KERN_INFO "TCP: Hash tables configured "
 	       "(established %d bind %d)\n",
 	       tcp_ehash_size << 1, tcp_bhash_size);
+
+	tcp_register_congestion_control(&tcp_reno);
 }
 
 EXPORT_SYMBOL(tcp_accept);

net/ipv4/tcp_bic.c

+/*
+ * Binary Increase Congestion control for TCP
+ *
+ * This is from the implementation of BICTCP in
+ * Lison-Xu, Kahaled Harfoush, and Injong Rhee.
+ *  "Binary Increase Congestion Control for Fast, Long Distance
+ *  Networks" in InfoComm 2004
+ * Available from:
+ *  http://www.csc.ncsu.edu/faculty/rhee/export/bitcp.pdf
+ *
+ * Unless BIC is enabled and congestion window is large
+ * this behaves the same as the original Reno.
+ */
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <net/tcp.h>
+
+
+#define BICTCP_BETA_SCALE    1024	/* Scale factor beta calculation
+					 * max_cwnd = snd_cwnd * beta
+					 */
+#define BICTCP_B		4	 /*
+					  * In binary search,
+					  * go to point (max+min)/N
+					  */
+
+static int fast_convergence = 1;
+static int max_increment = 32;
+static int low_window = 14;
+static int beta = 819;		/* = 819/1024 (BICTCP_BETA_SCALE) */
+static int low_utilization_threshold = 153;
+static int low_utilization_period = 2;
+static int initial_ssthresh = 100;
+static int smooth_part = 20;
+
+module_param(fast_convergence, int, 0644);
+MODULE_PARM_DESC(fast_convergence, "turn on/off fast convergence");
+module_param(max_increment, int, 0644);
+MODULE_PARM_DESC(max_increment, "Limit on increment allowed during binary search");
+module_param(low_window, int, 0644);
+MODULE_PARM_DESC(low_window, "lower bound on congestion window (for TCP friendliness)");
+module_param(beta, int, 0644);
+MODULE_PARM_DESC(beta, "beta for multiplicative increase");
+module_param(low_utilization_threshold, int, 0644);
+MODULE_PARM_DESC(low_utilization_threshold, "percent (scaled by 1024) for low utilization mode");
+module_param(low_utilization_period, int, 0644);
+MODULE_PARM_DESC(low_utilization_period, "if average delay exceeds then goto to low utilization mode (seconds)");
+module_param(initial_ssthresh, int, 0644);
+MODULE_PARM_DESC(initial_ssthresh, "initial value of slow start threshold");
+module_param(smooth_part, int, 0644);
+MODULE_PARM_DESC(smooth_part, "log(B/(B*Smin))/log(B/(B-1))+B, # of RTT from Wmax-B to Wmax");
+
+
+/* BIC TCP Parameters */
+struct bictcp {
+	u32	cnt;		/* increase cwnd by 1 after ACKs */
+	u32 	last_max_cwnd;	/* last maximum snd_cwnd */
+	u32	loss_cwnd;	/* congestion window at last loss */
+	u32	last_cwnd;	/* the last snd_cwnd */
+	u32	last_time;	/* time when updated last_cwnd */
+	u32	delay_min;	/* min delay */
+	u32	delay_max;	/* max delay */
+	u32	last_delay;
+	u8	low_utilization;/* 0: high; 1: low */
+	u32	low_utilization_start;	/* starting time of low utilization detection*/
+	u32	epoch_start;	/* beginning of an epoch */
+#define ACK_RATIO_SHIFT	4
+	u32	delayed_ack;	/* estimate the ratio of Packets/ACKs << 4 */
+};
+
+static inline void bictcp_reset(struct bictcp *ca)
+{
+	ca->cnt = 0;
+	ca->last_max_cwnd = 0;
+	ca->loss_cwnd = 0;
+	ca->last_cwnd = 0;
+	ca->last_time = 0;
+	ca->delay_min = 0;
+	ca->delay_max = 0;
+	ca->last_delay = 0;
+	ca->low_utilization = 0;
+	ca->low_utilization_start = 0;
+	ca->epoch_start = 0;
+	ca->delayed_ack = 2 << ACK_RATIO_SHIFT;
+}
+
+static void bictcp_init(struct tcp_sock *tp)
+{
+	bictcp_reset(tcp_ca(tp));
+	if (initial_ssthresh)
+		tp->snd_ssthresh = initial_ssthresh;
+}
+
+/*
+ * Compute congestion window to use.
+ */
+static inline void bictcp_update(struct bictcp *ca, u32 cwnd)
+{
+	if (ca->last_cwnd == cwnd &&
+	    (s32)(tcp_time_stamp - ca->last_time) <= HZ / 32)
+		return;
+
+	ca->last_cwnd = cwnd;
+	ca->last_time = tcp_time_stamp;
+
+	if (ca->epoch_start == 0) /* record the beginning of an epoch */
+		ca->epoch_start = tcp_time_stamp;
+
+	/* start off normal */
+	if (cwnd <= low_window) {
+		ca->cnt = cwnd;
+		return;
+	}
+
+	/* binary increase */
+	if (cwnd < ca->last_max_cwnd) {
+		__u32 	dist = (ca->last_max_cwnd - cwnd)
+			/ BICTCP_B;
+
+		if (dist > max_increment)
+			/* linear increase */
+			ca->cnt = cwnd / max_increment;
+		else if (dist <= 1U)
+			/* binary search increase */
+			ca->cnt = (cwnd * smooth_part) / BICTCP_B;
+		else
+			/* binary search increase */
+			ca->cnt = cwnd / dist;
+	} else {
+		/* slow start AMD linear increase */
+		if (cwnd < ca->last_max_cwnd + BICTCP_B)
+			/* slow start */
+			ca->cnt = (cwnd * smooth_part) / BICTCP_B;
+		else if (cwnd < ca->last_max_cwnd + max_increment*(BICTCP_B-1))
+			/* slow start */
+			ca->cnt = (cwnd * (BICTCP_B-1))
+				/ cwnd-ca->last_max_cwnd;
+		else
+			/* linear increase */
+			ca->cnt = cwnd / max_increment;
+	}
+
+	/* if in slow start or link utilization is very low */
+	if ( ca->loss_cwnd == 0 ||
+	     (cwnd > ca->loss_cwnd && ca->low_utilization)) {
+		if (ca->cnt > 20) /* increase cwnd 5% per RTT */
+			ca->cnt = 20;
+	}
+
+	ca->cnt = (ca->cnt << ACK_RATIO_SHIFT) / ca->delayed_ack;
+	if (ca->cnt == 0)			/* cannot be zero */
+		ca->cnt = 1;
+}
+
+
+/* Detect low utilization in congestion avoidance */
+static inline void bictcp_low_utilization(struct tcp_sock *tp, int flag)
+{
+	struct bictcp *ca = tcp_ca(tp);
+	u32 dist, delay;
+
+	/* No time stamp */
+	if (!(tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr) ||
+	     /* Discard delay samples right after fast recovery */
+	     tcp_time_stamp < ca->epoch_start + HZ ||
+	     /* this delay samples may not be accurate */
+	     flag == 0) {
+		ca->last_delay = 0;
+		goto notlow;
+	}
+
+	delay = ca->last_delay<<3;	/* use the same scale as tp->srtt*/
+	ca->last_delay = tcp_time_stamp - tp->rx_opt.rcv_tsecr;
+	if (delay == 0) 		/* no previous delay sample */
+		goto notlow;
+
+	/* first time call or link delay decreases */
+	if (ca->delay_min == 0 || ca->delay_min > delay) {
+		ca->delay_min = ca->delay_max = delay;
+		goto notlow;
+	}
+
+	if (ca->delay_max < delay)
+		ca->delay_max = delay;
+
+	/* utilization is low, if avg delay < dist*threshold
+	   for checking_period time */
+	dist = ca->delay_max - ca->delay_min;
+	if (dist <= ca->delay_min>>6 ||
+	    tp->srtt - ca->delay_min >=  (dist*low_utilization_threshold)>>10)
+		goto notlow;
+
+	if (ca->low_utilization_start == 0) {
+		ca->low_utilization = 0;
+		ca->low_utilization_start = tcp_time_stamp;
+	} else if ((s32)(tcp_time_stamp - ca->low_utilization_start)
+			> low_utilization_period*HZ) {
+		ca->low_utilization = 1;
+	}
+
+	return;
+
+ notlow:
+	ca->low_utilization = 0;
+	ca->low_utilization_start = 0;
+
+}
+
+static void bictcp_cong_avoid(struct tcp_sock *tp, u32 ack,
+			      u32 seq_rtt, u32 in_flight, int data_acked)
+{
+	struct bictcp *ca = tcp_ca(tp);
+
+	bictcp_low_utilization(tp, data_acked);
+
+	if (in_flight < tp->snd_cwnd)
+		return;
+
+	if (tp->snd_cwnd <= tp->snd_ssthresh) {
+		/* In "safe" area, increase. */
+		if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+			tp->snd_cwnd++;
+	} else {
+		bictcp_update(ca, tp->snd_cwnd);
+
+                /* In dangerous area, increase slowly.
+		 * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd
+		 */
+		if (tp->snd_cwnd_cnt >= ca->cnt) {
+			if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+				tp->snd_cwnd++;
+			tp->snd_cwnd_cnt = 0;
+		} else
+			tp->snd_cwnd_cnt++;
+	}
+
+}
+
+/*
+ *	behave like Reno until low_window is reached,
+ *	then increase congestion window slowly
+ */
+static u32 bictcp_recalc_ssthresh(struct tcp_sock *tp)
+{
+	struct bictcp *ca = tcp_ca(tp);
+
+	ca->epoch_start = 0;	/* end of epoch */
+
+	/* in case of wrong delay_max*/
+	if (ca->delay_min > 0 && ca->delay_max > ca->delay_min)
+		ca->delay_max = ca->delay_min
+			+ ((ca->delay_max - ca->delay_min)* 90) / 100;
+
+	/* Wmax and fast convergence */
+	if (tp->snd_cwnd < ca->last_max_cwnd && fast_convergence)
+		ca->last_max_cwnd = (tp->snd_cwnd * (BICTCP_BETA_SCALE + beta))
+			/ (2 * BICTCP_BETA_SCALE);
+	else
+		ca->last_max_cwnd = tp->snd_cwnd;
+
+	ca->loss_cwnd = tp->snd_cwnd;
+
+
+	if (tp->snd_cwnd <= low_window)
+		return max(tp->snd_cwnd >> 1U, 2U);
+	else
+		return max((tp->snd_cwnd * beta) / BICTCP_BETA_SCALE, 2U);
+}
+
+static u32 bictcp_undo_cwnd(struct tcp_sock *tp)
+{
+	struct bictcp *ca = tcp_ca(tp);
+
+	return max(tp->snd_cwnd, ca->last_max_cwnd);
+}
+
+static u32 bictcp_min_cwnd(struct tcp_sock *tp)
+{
+	return tp->snd_ssthresh;
+}
+
+static void bictcp_state(struct tcp_sock *tp, u8 new_state)
+{
+	if (new_state == TCP_CA_Loss)
+		bictcp_reset(tcp_ca(tp));
+}
+
+/* Track delayed acknowledgement ratio using sliding window
+ * ratio = (15*ratio + sample) / 16
+ */
+static void bictcp_acked(struct tcp_sock *tp, u32 cnt)
+{
+	if (cnt > 0 && 	tp->ca_state == TCP_CA_Open) {
+		struct bictcp *ca = tcp_ca(tp);
+		cnt -= ca->delayed_ack >> ACK_RATIO_SHIFT;
+		ca->delayed_ack += cnt;
+	}
+}
+
+
+static struct tcp_congestion_ops bictcp = {
+	.init		= bictcp_init,
+	.ssthresh	= bictcp_recalc_ssthresh,
+	.cong_avoid	= bictcp_cong_avoid,
+	.set_state	= bictcp_state,
+	.undo_cwnd	= bictcp_undo_cwnd,
+	.min_cwnd	= bictcp_min_cwnd,
+	.pkts_acked     = bictcp_acked,
+	.owner		= THIS_MODULE,
+	.name		= "bic",
+};
+
+static int __init bictcp_register(void)
+{
+	BUG_ON(sizeof(struct bictcp) > TCP_CA_PRIV_SIZE);
+	return tcp_register_congestion_control(&bictcp);
+}
+
+static void __exit bictcp_unregister(void)
+{
+	tcp_unregister_congestion_control(&bictcp);
+}
+
+module_init(bictcp_register);
+module_exit(bictcp_unregister);
+
+MODULE_AUTHOR("Stephen Hemminger");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("BIC TCP");

net/ipv4/tcp_cong.c

+/*
+ * Plugable TCP congestion control support and newReno
+ * congestion control.
+ * Based on ideas from I/O scheduler suport and Web100.
+ *
+ * Copyright (C) 2005 Stephen Hemminger <shemminger@osdl.org>
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/types.h>
+#include <linux/list.h>
+#include <net/tcp.h>
+
+static DEFINE_SPINLOCK(tcp_cong_list_lock);
+static LIST_HEAD(tcp_cong_list);
+
+/* Simple linear search, don't expect many entries! */
+static struct tcp_congestion_ops *tcp_ca_find(const char *name)
+{
+	struct tcp_congestion_ops *e;
+
+	list_for_each_entry(e, &tcp_cong_list, list) {
+		if (strcmp(e->name, name) == 0)
+			return e;
+	}
+
+	return NULL;
+}
+
+/*
+ * Attach new congestion control algorthim to the list
+ * of available options.
+ */
+int tcp_register_congestion_control(struct tcp_congestion_ops *ca)
+{
+	int ret = 0;
+
+	/* all algorithms must implement ssthresh and cong_avoid ops */
+	if (!ca->ssthresh || !ca->cong_avoid || !ca->min_cwnd) {
+		printk(KERN_ERR "TCP %s does not implement required ops\n",
+		       ca->name);
+		return -EINVAL;
+	}
+
+	spin_lock(&tcp_cong_list_lock);
+	if (tcp_ca_find(ca->name)) {
+		printk(KERN_NOTICE "TCP %s already registered\n", ca->name);
+		ret = -EEXIST;
+	} else {
+		list_add_rcu(&ca->list, &tcp_cong_list);
+		printk(KERN_INFO "TCP %s registered\n", ca->name);
+	}
+	spin_unlock(&tcp_cong_list_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tcp_register_congestion_control);
+
+/*
+ * Remove congestion control algorithm, called from
+ * the module's remove function.  Module ref counts are used
+ * to ensure that this can't be done till all sockets using
+ * that method are closed.
+ */
+void tcp_unregister_congestion_control(struct tcp_congestion_ops *ca)
+{
+	spin_lock(&tcp_cong_list_lock);
+	list_del_rcu(&ca->list);
+	spin_unlock(&tcp_cong_list_lock);
+}
+EXPORT_SYMBOL_GPL(tcp_unregister_congestion_control);
+
+/* Assign choice of congestion control. */
+void tcp_init_congestion_control(struct tcp_sock *tp)
+{
+	struct tcp_congestion_ops *ca;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
+		if (try_module_get(ca->owner)) {
+			tp->ca_ops = ca;
+			break;
+		}
+
+	}
+	rcu_read_unlock();
+
+	if (tp->ca_ops->init)
+		tp->ca_ops->init(tp);
+}
+
+/* Manage refcounts on socket close. */
+void tcp_cleanup_congestion_control(struct tcp_sock *tp)
+{
+	if (tp->ca_ops->release)
+		tp->ca_ops->release(tp);
+	module_put(tp->ca_ops->owner);
+}
+
+/* Used by sysctl to change default congestion control */
+int tcp_set_default_congestion_control(const char *name)
+{
+	struct tcp_congestion_ops *ca;
+	int ret = -ENOENT;
+
+	spin_lock(&tcp_cong_list_lock);
+	ca = tcp_ca_find(name);
+#ifdef CONFIG_KMOD
+	if (!ca) {
+		spin_unlock(&tcp_cong_list_lock);
+
+		request_module("tcp_%s", name);
+		spin_lock(&tcp_cong_list_lock);
+		ca = tcp_ca_find(name);
+	}
+#endif
+
+	if (ca) {
+		list_move(&ca->list, &tcp_cong_list);
+		ret = 0;
+	}
+	spin_unlock(&tcp_cong_list_lock);
+
+	return ret;
+}
+
+/* Get current default congestion control */
+void tcp_get_default_congestion_control(char *name)
+{
+	struct tcp_congestion_ops *ca;
+	/* We will always have reno... */
+	BUG_ON(list_empty(&tcp_cong_list));
+
+	rcu_read_lock();
+	ca = list_entry(tcp_cong_list.next, struct tcp_congestion_ops, list);
+	strncpy(name, ca->name, TCP_CA_NAME_MAX);
+	rcu_read_unlock();
+}
+
+/*
+ * TCP Reno congestion control
+ * This is special case used for fallback as well.
+ */
+/* This is Jacobson's slow start and congestion avoidance.
+ * SIGCOMM '88, p. 328.
+ */
+void tcp_reno_cong_avoid(struct tcp_sock *tp, u32 ack, u32 rtt, u32 in_flight,
+			 int flag)
+{
+	if (in_flight < tp->snd_cwnd)
+		return;
+
+        if (tp->snd_cwnd <= tp->snd_ssthresh) {
+                /* In "safe" area, increase. */
+		if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+			tp->snd_cwnd++;
+	} else {
+                /* In dangerous area, increase slowly.
+		 * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd
+		 */
+		if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
+			if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+				tp->snd_cwnd++;
+			tp->snd_cwnd_cnt = 0;
+		} else
+			tp->snd_cwnd_cnt++;
+	}
+}
+EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid);
+
+/* Slow start threshold is half the congestion window (min 2) */
+u32 tcp_reno_ssthresh(struct tcp_sock *tp)
+{
+	return max(tp->snd_cwnd >> 1U, 2U);
+}
+EXPORT_SYMBOL_GPL(tcp_reno_ssthresh);
+
+/* Lower bound on congestion window. */
+u32 tcp_reno_min_cwnd(struct tcp_sock *tp)
+{
+	return tp->snd_ssthresh/2;
+}
+EXPORT_SYMBOL_GPL(tcp_reno_min_cwnd);
+
+struct tcp_congestion_ops tcp_reno = {
+	.name		= "reno",
+	.owner		= THIS_MODULE,
+	.ssthresh	= tcp_reno_ssthresh,
+	.cong_avoid	= tcp_reno_cong_avoid,
+	.min_cwnd	= tcp_reno_min_cwnd,
+};
+
+EXPORT_SYMBOL_GPL(tcp_reno);

net/ipv4/tcp_diag.c

@@ -42,15 +42,8 @@ struct tcpdiag_entry
 
 static struct sock *tcpnl;
 
-
 #define TCPDIAG_PUT(skb, attrtype, attrlen) \
-({ int rtalen = RTA_LENGTH(attrlen);        \
-   struct rtattr *rta;                      \
-   if (skb_tailroom(skb) < RTA_ALIGN(rtalen)) goto nlmsg_failure; \
-   rta = (void*)__skb_put(skb, RTA_ALIGN(rtalen)); \
-   rta->rta_type = attrtype;                \
-   rta->rta_len = rtalen;                   \
-   RTA_DATA(rta); })
+	RTA_DATA(__RTA_PUT(skb, attrtype, attrlen))
 
 static int tcpdiag_fill(struct sk_buff *skb, struct sock *sk,
 			int ext, u32 pid, u32 seq, u16 nlmsg_flags)
@@ -61,7 +54,6 @@ static int tcpdiag_fill(struct sk_buff *skb, struct sock *sk,
 	struct nlmsghdr  *nlh;
 	struct tcp_info  *info = NULL;
 	struct tcpdiag_meminfo  *minfo = NULL;
-	struct tcpvegas_info *vinfo = NULL;
 	unsigned char	 *b = skb->tail;
 
 	nlh = NLMSG_PUT(skb, pid, seq, TCPDIAG_GETSOCK, sizeof(*r));
@@ -73,9 +65,11 @@ static int tcpdiag_fill(struct sk_buff *skb, struct sock *sk,
 		if (ext & (1<<(TCPDIAG_INFO-1)))
 			info = TCPDIAG_PUT(skb, TCPDIAG_INFO, sizeof(*info));
 		
-		if ((tcp_is_westwood(tp) || tcp_is_vegas(tp))
-		    && (ext & (1<<(TCPDIAG_VEGASINFO-1))))
-			vinfo = TCPDIAG_PUT(skb, TCPDIAG_VEGASINFO, sizeof(*vinfo));
+		if (ext & (1<<(TCPDIAG_CONG-1))) {
+			size_t len = strlen(tp->ca_ops->name);
+			strcpy(TCPDIAG_PUT(skb, TCPDIAG_CONG, len+1),
+			       tp->ca_ops->name);
+		}
 	}
 	r->tcpdiag_family = sk->sk_family;
 	r->tcpdiag_state = sk->sk_state;
@@ -166,23 +160,13 @@ static int tcpdiag_fill(struct sk_buff *skb, struct sock *sk,
 	if (info) 
 		tcp_get_info(sk, info);
 
-	if (vinfo) {
-		if (tcp_is_vegas(tp)) {
-			vinfo->tcpv_enabled = tp->vegas.doing_vegas_now;
-			vinfo->tcpv_rttcnt = tp->vegas.cntRTT;
-			vinfo->tcpv_rtt = jiffies_to_usecs(tp->vegas.baseRTT);
-			vinfo->tcpv_minrtt = jiffies_to_usecs(tp->vegas.minRTT);
-		} else {
-			vinfo->tcpv_enabled = 0;
-			vinfo->tcpv_rttcnt = 0;
-			vinfo->tcpv_rtt = jiffies_to_usecs(tp->westwood.rtt);
-			vinfo->tcpv_minrtt = jiffies_to_usecs(tp->westwood.rtt_min);
-		}
-	}
+	if (sk->sk_state < TCP_TIME_WAIT && tp->ca_ops->get_info)
+		tp->ca_ops->get_info(tp, ext, skb);
 
 	nlh->nlmsg_len = skb->tail - b;
 	return skb->len;
 
+rtattr_failure:
 nlmsg_failure:
 	skb_trim(skb, b - skb->data);
 	return -1;

net/ipv4/tcp_highspeed.c

+/*
+ * Sally Floyd's High Speed TCP (RFC 3649) congestion control
+ *
+ * See http://www.icir.org/floyd/hstcp.html
+ *
+ * John Heffner <jheffner@psc.edu>
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <net/tcp.h>
+
+
+/* From AIMD tables from RFC 3649 appendix B,
+ * with fixed-point MD scaled <<8.
+ */
+static const struct hstcp_aimd_val {
+        unsigned int cwnd;
+        unsigned int md;
+} hstcp_aimd_vals[] = {
+ {     38,  128, /*  0.50 */ },
+ {    118,  112, /*  0.44 */ },
+ {    221,  104, /*  0.41 */ },
+ {    347,   98, /*  0.38 */ },
+ {    495,   93, /*  0.37 */ },
+ {    663,   89, /*  0.35 */ },
+ {    851,   86, /*  0.34 */ },
+ {   1058,   83, /*  0.33 */ },
+ {   1284,   81, /*  0.32 */ },
+ {   1529,   78, /*  0.31 */ },
+ {   1793,   76, /*  0.30 */ },
+ {   2076,   74, /*  0.29 */ },
+ {   2378,   72, /*  0.28 */ },
+ {   2699,   71, /*  0.28 */ },
+ {   3039,   69, /*  0.27 */ },
+ {   3399,   68, /*  0.27 */ },
+ {   3778,   66, /*  0.26 */ },
+ {   4177,   65, /*  0.26 */ },
+ {   4596,   64, /*  0.25 */ },
+ {   5036,   62, /*  0.25 */ },
+ {   5497,   61, /*  0.24 */ },
+ {   5979,   60, /*  0.24 */ },
+ {   6483,   59, /*  0.23 */ },
+ {   7009,   58, /*  0.23 */ },
+ {   7558,   57, /*  0.22 */ },
+ {   8130,   56, /*  0.22 */ },
+ {   8726,   55, /*  0.22 */ },
+ {   9346,   54, /*  0.21 */ },
+ {   9991,   53, /*  0.21 */ },
+ {  10661,   52, /*  0.21 */ },
+ {  11358,   52, /*  0.20 */ },
+ {  12082,   51, /*  0.20 */ },
+ {  12834,   50, /*  0.20 */ },
+ {  13614,   49, /*  0.19 */ },
+ {  14424,   48, /*  0.19 */ },
+ {  15265,   48, /*  0.19 */ },
+ {  16137,   47, /*  0.19 */ },
+ {  17042,   46, /*  0.18 */ },
+ {  17981,   45, /*  0.18 */ },
+ {  18955,   45, /*  0.18 */ },
+ {  19965,   44, /*  0.17 */ },
+ {  21013,   43, /*  0.17 */ },
+ {  22101,   43, /*  0.17 */ },
+ {  23230,   42, /*  0.17 */ },
+ {  24402,   41, /*  0.16 */ },
+ {  25618,   41, /*  0.16 */ },
+ {  26881,   40, /*  0.16 */ },
+ {  28193,   39, /*  0.16 */ },
+ {  29557,   39, /*  0.15 */ },
+ {  30975,   38, /*  0.15 */ },
+ {  32450,   38, /*  0.15 */ },
+ {  33986,   37, /*  0.15 */ },
+ {  35586,   36, /*  0.14 */ },
+ {  37253,   36, /*  0.14 */ },
+ {  38992,   35, /*  0.14 */ },
+ {  40808,   35, /*  0.14 */ },
+ {  42707,   34, /*  0.13 */ },
+ {  44694,   33, /*  0.13 */ },
+ {  46776,   33, /*  0.13 */ },
+ {  48961,   32, /*  0.13 */ },
+ {  51258,   32, /*  0.13 */ },
+ {  53677,   31, /*  0.12 */ },
+ {  56230,   30, /*  0.12 */ },
+ {  58932,   30, /*  0.12 */ },
+ {  61799,   29, /*  0.12 */ },
+ {  64851,   28, /*  0.11 */ },
+ {  68113,   28, /*  0.11 */ },
+ {  71617,   27, /*  0.11 */ },
+ {  75401,   26, /*  0.10 */ },
+ {  79517,   26, /*  0.10 */ },
+ {  84035,   25, /*  0.10 */ },
+ {  89053,   24, /*  0.10 */ },
+};
+
+#define HSTCP_AIMD_MAX	ARRAY_SIZE(hstcp_aimd_vals)
+
+struct hstcp {
+	u32	ai;
+};
+
+static void hstcp_init(struct tcp_sock *tp)
+{
+	struct hstcp *ca = tcp_ca(tp);
+
+	ca->ai = 0;
+
+	/* Ensure the MD arithmetic works.  This is somewhat pedantic,
+	 * since I don't think we will see a cwnd this large. :) */
+	tp->snd_cwnd_clamp = min_t(u32, tp->snd_cwnd_clamp, 0xffffffff/128);
+}
+
+static void hstcp_cong_avoid(struct tcp_sock *tp, u32 adk, u32 rtt,
+			     u32 in_flight, int good)
+{
+	struct hstcp *ca = tcp_ca(tp);
+
+	if (in_flight < tp->snd_cwnd)
+		return;
+
+	if (tp->snd_cwnd <= tp->snd_ssthresh) {
+		if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+			tp->snd_cwnd++;
+	} else {
+		/* Update AIMD parameters */
+		if (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd) {
+			while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd &&
+			       ca->ai < HSTCP_AIMD_MAX)
+				ca->ai++;
+		} else if (tp->snd_cwnd < hstcp_aimd_vals[ca->ai].cwnd) {
+			while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd &&
+			       ca->ai > 0)
+				ca->ai--;
+		}
+
+		/* Do additive increase */
+		if (tp->snd_cwnd < tp->snd_cwnd_clamp) {
+			tp->snd_cwnd_cnt += ca->ai;
+			if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
+				tp->snd_cwnd++;
+				tp->snd_cwnd_cnt -= tp->snd_cwnd;
+			}
+		}
+	}
+}
+
+static u32 hstcp_ssthresh(struct tcp_sock *tp)
+{
+	struct hstcp *ca = tcp_ca(tp);
+
+	/* Do multiplicative decrease */
+	return max(tp->snd_cwnd - ((tp->snd_cwnd * hstcp_aimd_vals[ca->ai].md) >> 8), 2U);
+}
+
+
+static struct tcp_congestion_ops tcp_highspeed = {
+	.init		= hstcp_init,
+	.ssthresh	= hstcp_ssthresh,
+	.cong_avoid	= hstcp_cong_avoid,
+	.min_cwnd	= tcp_reno_min_cwnd,
+
+	.owner		= THIS_MODULE,
+	.name		= "highspeed"
+};
+
+static int __init hstcp_register(void)
+{
+	BUG_ON(sizeof(struct hstcp) > TCP_CA_PRIV_SIZE);
+	return tcp_register_congestion_control(&tcp_highspeed);
+}
+
+static void __exit hstcp_unregister(void)
+{
+	tcp_unregister_congestion_control(&tcp_highspeed);
+}
+
+module_init(hstcp_register);
+module_exit(hstcp_unregister);
+
+MODULE_AUTHOR("John Heffner");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("High Speed TCP");

net/ipv4/tcp_htcp.c

+/*
+ * H-TCP congestion control. The algorithm is detailed in:
+ * R.N.Shorten, D.J.Leith:
+ *   "H-TCP: TCP for high-speed and long-distance networks"
+ *   Proc. PFLDnet, Argonne, 2004.
+ * http://www.hamilton.ie/net/htcp3.pdf
+ */
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <net/tcp.h>
+
+#define ALPHA_BASE	(1<<7)  /* 1.0 with shift << 7 */
+#define BETA_MIN	(1<<6)  /* 0.5 with shift << 7 */
+#define BETA_MAX	102	/* 0.8 with shift << 7 */
+
+static int use_rtt_scaling = 1;
+module_param(use_rtt_scaling, int, 0644);
+MODULE_PARM_DESC(use_rtt_scaling, "turn on/off RTT scaling");
+
+static int use_bandwidth_switch = 1;
+module_param(use_bandwidth_switch, int, 0644);
+MODULE_PARM_DESC(use_bandwidth_switch, "turn on/off bandwidth switcher");
+
+struct htcp {
+	u16	alpha;		/* Fixed point arith, << 7 */
+	u8	beta;           /* Fixed point arith, << 7 */
+	u8	modeswitch;     /* Delay modeswitch until we had at least one congestion event */
+	u8	ccount;		/* Number of RTTs since last congestion event */
+	u8	undo_ccount;
+	u16	packetcount;
+	u32	minRTT;
+	u32	maxRTT;
+	u32	snd_cwnd_cnt2;
+
+	u32	undo_maxRTT;
+	u32	undo_old_maxB;
+
+	/* Bandwidth estimation */
+	u32	minB;
+	u32	maxB;
+	u32	old_maxB;
+	u32	Bi;
+	u32	lasttime;
+};
+
+static inline void htcp_reset(struct htcp *ca)
+{
+	ca->undo_ccount = ca->ccount;
+	ca->undo_maxRTT = ca->maxRTT;
+	ca->undo_old_maxB = ca->old_maxB;
+
+	ca->ccount = 0;
+	ca->snd_cwnd_cnt2 = 0;
+}
+
+static u32 htcp_cwnd_undo(struct tcp_sock *tp)
+{
+	struct htcp *ca = tcp_ca(tp);
+	ca->ccount = ca->undo_ccount;
+	ca->maxRTT = ca->undo_maxRTT;
+	ca->old_maxB = ca->undo_old_maxB;
+	return max(tp->snd_cwnd, (tp->snd_ssthresh<<7)/ca->beta);
+}
+
+static inline void measure_rtt(struct tcp_sock *tp)
+{
+	struct htcp *ca = tcp_ca(tp);
+	u32 srtt = tp->srtt>>3;
+
+	/* keep track of minimum RTT seen so far, minRTT is zero at first */
+	if (ca->minRTT > srtt || !ca->minRTT)
+		ca->minRTT = srtt;
+
+	/* max RTT */
+	if (tp->ca_state == TCP_CA_Open && tp->snd_ssthresh < 0xFFFF && ca->ccount > 3) {
+		if (ca->maxRTT < ca->minRTT)
+			ca->maxRTT = ca->minRTT;
+		if (ca->maxRTT < srtt && srtt <= ca->maxRTT+HZ/50)
+			ca->maxRTT = srtt;
+	}
+}
+
+static void measure_achieved_throughput(struct tcp_sock *tp, u32 pkts_acked)
+{
+	struct htcp *ca = tcp_ca(tp);
+	u32 now = tcp_time_stamp;
+
+	/* achieved throughput calculations */
+	if (tp->ca_state != TCP_CA_Open && tp->ca_state != TCP_CA_Disorder) {
+		ca->packetcount = 0;
+		ca->lasttime = now;
+		return;
+	}
+
+	ca->packetcount += pkts_acked;
+
+	if (ca->packetcount >= tp->snd_cwnd - (ca->alpha>>7? : 1)
+			&& now - ca->lasttime >= ca->minRTT
+			&& ca->minRTT > 0) {
+		__u32 cur_Bi = ca->packetcount*HZ/(now - ca->lasttime);
+		if (ca->ccount <= 3) {
+			/* just after backoff */
+			ca->minB = ca->maxB = ca->Bi = cur_Bi;
+		} else {
+			ca->Bi = (3*ca->Bi + cur_Bi)/4;
+			if (ca->Bi > ca->maxB)
+				ca->maxB = ca->Bi;
+			if (ca->minB > ca->maxB)
+				ca->minB = ca->maxB;
+		}
+		ca->packetcount = 0;
+		ca->lasttime = now;
+	}
+}
+
+static inline void htcp_beta_update(struct htcp *ca, u32 minRTT, u32 maxRTT)
+{
+	if (use_bandwidth_switch) {
+		u32 maxB = ca->maxB;
+		u32 old_maxB = ca->old_maxB;
+		ca->old_maxB = ca->maxB;
+
+		if (!between(5*maxB, 4*old_maxB, 6*old_maxB)) {
+			ca->beta = BETA_MIN;
+			ca->modeswitch = 0;
+			return;
+		}
+	}
+
+	if (ca->modeswitch && minRTT > max(HZ/100, 1) && maxRTT) {
+		ca->beta = (minRTT<<7)/maxRTT;
+		if (ca->beta < BETA_MIN)
+			ca->beta = BETA_MIN;
+		else if (ca->beta > BETA_MAX)
+			ca->beta = BETA_MAX;
+	} else {
+		ca->beta = BETA_MIN;
+		ca->modeswitch = 1;
+	}
+}
+
+static inline void htcp_alpha_update(struct htcp *ca)
+{
+	u32 minRTT = ca->minRTT;
+	u32 factor = 1;
+	u32 diff = ca->ccount * minRTT; /* time since last backoff */
+
+	if (diff > HZ) {
+		diff -= HZ;
+		factor = 1+ ( 10*diff + ((diff/2)*(diff/2)/HZ) )/HZ;
+	}
+
+	if (use_rtt_scaling && minRTT) {
+		u32 scale = (HZ<<3)/(10*minRTT);
+		scale = min(max(scale, 1U<<2), 10U<<3); /* clamping ratio to interval [0.5,10]<<3 */
+		factor = (factor<<3)/scale;
+		if (!factor)
+			factor = 1;
+	}
+
+	ca->alpha = 2*factor*((1<<7)-ca->beta);
+	if (!ca->alpha)
+		ca->alpha = ALPHA_BASE;
+}
+
+/* After we have the rtt data to calculate beta, we'd still prefer to wait one
+ * rtt before we adjust our beta to ensure we are working from a consistent
+ * data.
+ *
+ * This function should be called when we hit a congestion event since only at
+ * that point do we really have a real sense of maxRTT (the queues en route
+ * were getting just too full now).
+ */
+static void htcp_param_update(struct tcp_sock *tp)
+{
+	struct htcp *ca = tcp_ca(tp);
+	u32 minRTT = ca->minRTT;
+	u32 maxRTT = ca->maxRTT;
+
+	htcp_beta_update(ca, minRTT, maxRTT);
+	htcp_alpha_update(ca);
+
+	/* add slowly fading memory for maxRTT to accommodate routing changes etc */
+	if (minRTT > 0 && maxRTT > minRTT)
+		ca->maxRTT = minRTT + ((maxRTT-minRTT)*95)/100;
+}
+
+static u32 htcp_recalc_ssthresh(struct tcp_sock *tp)
+{
+	struct htcp *ca = tcp_ca(tp);
+	htcp_param_update(tp);
+	return max((tp->snd_cwnd * ca->beta) >> 7, 2U);
+}
+
+static void htcp_cong_avoid(struct tcp_sock *tp, u32 ack, u32 rtt,
+			    u32 in_flight, int data_acked)
+{
+	struct htcp *ca = tcp_ca(tp);
+
+	if (in_flight < tp->snd_cwnd)
+		return;
+
+        if (tp->snd_cwnd <= tp->snd_ssthresh) {
+                /* In "safe" area, increase. */
+		if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+			tp->snd_cwnd++;
+	} else {
+		measure_rtt(tp);
+
+		/* keep track of number of round-trip times since last backoff event */
+		if (ca->snd_cwnd_cnt2++ > tp->snd_cwnd) {
+			ca->ccount++;
+			ca->snd_cwnd_cnt2 = 0;
+			htcp_alpha_update(ca);
+		}
+
+                /* In dangerous area, increase slowly.
+		 * In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd
+		 */
+		if ((tp->snd_cwnd_cnt++ * ca->alpha)>>7 >= tp->snd_cwnd) {
+			if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+				tp->snd_cwnd++;
+			tp->snd_cwnd_cnt = 0;
+			ca->ccount++;
+		}
+	}
+}
+
+/* Lower bound on congestion window. */
+static u32 htcp_min_cwnd(struct tcp_sock *tp)
+{
+	return tp->snd_ssthresh;
+}
+
+
+static void htcp_init(struct tcp_sock *tp)
+{
+	struct htcp *ca = tcp_ca(tp);
+
+	memset(ca, 0, sizeof(struct htcp));
+	ca->alpha = ALPHA_BASE;
+	ca->beta = BETA_MIN;
+}
+
+static void htcp_state(struct tcp_sock *tp, u8 new_state)
+{
+	switch (new_state) {
+	case TCP_CA_CWR:
+	case TCP_CA_Recovery:
+	case TCP_CA_Loss:
+		htcp_reset(tcp_ca(tp));
+		break;
+	}
+}
+
+static struct tcp_congestion_ops htcp = {
+	.init		= htcp_init,
+	.ssthresh	= htcp_recalc_ssthresh,
+	.min_cwnd	= htcp_min_cwnd,
+	.cong_avoid	= htcp_cong_avoid,
+	.set_state	= htcp_state,
+	.undo_cwnd	= htcp_cwnd_undo,
+	.pkts_acked	= measure_achieved_throughput,
+	.owner		= THIS_MODULE,
+	.name		= "htcp",
+};
+
+static int __init htcp_register(void)
+{
+	BUG_ON(sizeof(struct htcp) > TCP_CA_PRIV_SIZE);
+	BUILD_BUG_ON(BETA_MIN >= BETA_MAX);
+	if (!use_bandwidth_switch)
+		htcp.pkts_acked = NULL;
+	return tcp_register_congestion_control(&htcp);
+}
+
+static void __exit htcp_unregister(void)
+{
+	tcp_unregister_congestion_control(&htcp);
+}
+
+module_init(htcp_register);
+module_exit(htcp_unregister);
+
+MODULE_AUTHOR("Baruch Even");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("H-TCP");

net/ipv4/tcp_hybla.c

+/*
+ * TCP HYBLA
+ *
+ * TCP-HYBLA Congestion control algorithm, based on:
+ *   C.Caini, R.Firrincieli, "TCP-Hybla: A TCP Enhancement
+ *   for Heterogeneous Networks",
+ *   International Journal on satellite Communications,
+ *				       September 2004
+ *    Daniele Lacamera
+ *    root at danielinux.net
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <net/tcp.h>
+
+/* Tcp Hybla structure. */
+struct hybla {
+	u8    hybla_en;
+	u32   snd_cwnd_cents; /* Keeps increment values when it is <1, <<7 */
+	u32   rho;	      /* Rho parameter, integer part  */
+	u32   rho2;	      /* Rho * Rho, integer part */
+	u32   rho_3ls;	      /* Rho parameter, <<3 */
+	u32   rho2_7ls;	      /* Rho^2, <<7	*/
+	u32   minrtt;	      /* Minimum smoothed round trip time value seen */
+};
+
+/* Hybla reference round trip time (default= 1/40 sec = 25 ms),
+   expressed in jiffies */
+static int rtt0 = 25;
+module_param(rtt0, int, 0644);
+MODULE_PARM_DESC(rtt0, "reference rout trip time (ms)");
+
+
+/* This is called to refresh values for hybla parameters */
+static inline void hybla_recalc_param (struct tcp_sock *tp)
+{
+	struct hybla *ca = tcp_ca(tp);
+
+	ca->rho_3ls = max_t(u32, tp->srtt / msecs_to_jiffies(rtt0), 8);
+	ca->rho = ca->rho_3ls >> 3;
+	ca->rho2_7ls = (ca->rho_3ls * ca->rho_3ls) << 1;
+	ca->rho2 = ca->rho2_7ls >>7;
+}
+
+static void hybla_init(struct tcp_sock *tp)
+{
+	struct hybla *ca = tcp_ca(tp);
+
+	ca->rho = 0;
+	ca->rho2 = 0;
+	ca->rho_3ls = 0;
+	ca->rho2_7ls = 0;
+	ca->snd_cwnd_cents = 0;
+	ca->hybla_en = 1;
+	tp->snd_cwnd = 2;
+	tp->snd_cwnd_clamp = 65535;
+
+	/* 1st Rho measurement based on initial srtt */
+	hybla_recalc_param(tp);
+
+	/* set minimum rtt as this is the 1st ever seen */
+	ca->minrtt = tp->srtt;
+	tp->snd_cwnd = ca->rho;
+}
+
+static void hybla_state(struct tcp_sock *tp, u8 ca_state)
+{
+	struct hybla *ca = tcp_ca(tp);
+
+	ca->hybla_en = (ca_state == TCP_CA_Open);
+}
+
+static inline u32 hybla_fraction(u32 odds)
+{
+	static const u32 fractions[] = {
+		128, 139, 152, 165, 181, 197, 215, 234,
+	};
+
+	return (odds < ARRAY_SIZE(fractions)) ? fractions[odds] : 128;
+}
+
+/* TCP Hybla main routine.
+ * This is the algorithm behavior:
+ *     o Recalc Hybla parameters if min_rtt has changed
+ *     o Give cwnd a new value based on the model proposed
+ *     o remember increments <1
+ */
+static void hybla_cong_avoid(struct tcp_sock *tp, u32 ack, u32 rtt,
+			    u32 in_flight, int flag)
+{
+	struct hybla *ca = tcp_ca(tp);
+	u32 increment, odd, rho_fractions;
+	int is_slowstart = 0;
+
+	/*  Recalculate rho only if this srtt is the lowest */
+	if (tp->srtt < ca->minrtt){
+		hybla_recalc_param(tp);
+		ca->minrtt = tp->srtt;
+	}
+
+	if (!ca->hybla_en)
+		return tcp_reno_cong_avoid(tp, ack, rtt, in_flight, flag);
+
+	if (in_flight < tp->snd_cwnd)
+		return;
+
+	if (ca->rho == 0)
+		hybla_recalc_param(tp);
+
+	rho_fractions = ca->rho_3ls - (ca->rho << 3);
+
+	if (tp->snd_cwnd < tp->snd_ssthresh) {
+		/*
+		 * slow start
+		 *      INC = 2^RHO - 1
+		 * This is done by splitting the rho parameter
+		 * into 2 parts: an integer part and a fraction part.
+		 * Inrement<<7 is estimated by doing:
+		 *	       [2^(int+fract)]<<7
+		 * that is equal to:
+		 *	       (2^int)	*  [(2^fract) <<7]
+		 * 2^int is straightly computed as 1<<int,
+		 * while we will use hybla_slowstart_fraction_increment() to
+		 * calculate 2^fract in a <<7 value.
+		 */
+		is_slowstart = 1;
+		increment = ((1 << ca->rho) * hybla_fraction(rho_fractions))
+			- 128;
+	} else {
+		/*
+		 * congestion avoidance
+		 * INC = RHO^2 / W
+		 * as long as increment is estimated as (rho<<7)/window
+		 * it already is <<7 and we can easily count its fractions.
+		 */
+		increment = ca->rho2_7ls / tp->snd_cwnd;
+		if (increment < 128)
+			tp->snd_cwnd_cnt++;
+	}
+
+	odd = increment % 128;
+	tp->snd_cwnd += increment >> 7;
+	ca->snd_cwnd_cents += odd;
+
+	/* check when fractions goes >=128 and increase cwnd by 1. */
+	while(ca->snd_cwnd_cents >= 128) {
+		tp->snd_cwnd++;
+		ca->snd_cwnd_cents -= 128;
+		tp->snd_cwnd_cnt = 0;
+	}
+
+	/* clamp down slowstart cwnd to ssthresh value. */
+	if (is_slowstart)
+		tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
+
+	tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp);
+}
+
+static struct tcp_congestion_ops tcp_hybla = {
+	.init		= hybla_init,
+	.ssthresh	= tcp_reno_ssthresh,
+	.min_cwnd	= tcp_reno_min_cwnd,
+	.cong_avoid	= hybla_cong_avoid,
+	.set_state	= hybla_state,
+
+	.owner		= THIS_MODULE,
+	.name		= "hybla"
+};
+
+static int __init hybla_register(void)
+{
+	BUG_ON(sizeof(struct hybla) > TCP_CA_PRIV_SIZE);
+	return tcp_register_congestion_control(&tcp_hybla);
+}
+
+static void __exit hybla_unregister(void)
+{
+	tcp_unregister_congestion_control(&tcp_hybla);
+}
+
+module_init(hybla_register);
+module_exit(hybla_unregister);
+
+MODULE_AUTHOR("Daniele Lacamera");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("TCP Hybla");

net/ipv4/tcp_ipv4.c

@@ -2048,6 +2048,7 @@ static int tcp_v4_init_sock(struct sock *sk)
 	tp->mss_cache_std = tp->mss_cache = 536;
 
 	tp->reordering = sysctl_tcp_reordering;
+	tp->ca_ops = &tcp_reno;
 
 	sk->sk_state = TCP_CLOSE;
 
@@ -2070,6 +2071,8 @@ int tcp_v4_destroy_sock(struct sock *sk)
 
 	tcp_clear_xmit_timers(sk);
 
+	tcp_cleanup_congestion_control(tp);
+
 	/* Cleanup up the write buffer. */
   	sk_stream_writequeue_purge(sk);
 

net/ipv4/tcp_minisocks.c

@@ -774,6 +774,8 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
 		newtp->frto_counter = 0;
 		newtp->frto_highmark = 0;
 
+		newtp->ca_ops = &tcp_reno;
+
 		tcp_set_ca_state(newtp, TCP_CA_Open);
 		tcp_init_xmit_timers(newsk);
 		skb_queue_head_init(&newtp->out_of_order_queue);
@@ -842,8 +844,6 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
 		if (newtp->ecn_flags&TCP_ECN_OK)
 			sock_set_flag(newsk, SOCK_NO_LARGESEND);
 
-		tcp_ca_init(newtp);
-
 		TCP_INC_STATS_BH(TCP_MIB_PASSIVEOPENS);
 	}
 	return newsk;

net/ipv4/tcp_output.c

@@ -111,8 +111,7 @@ static void tcp_cwnd_restart(struct tcp_sock *tp, struct dst_entry *dst)
 	u32 restart_cwnd = tcp_init_cwnd(tp, dst);
 	u32 cwnd = tp->snd_cwnd;
 
-	if (tcp_is_vegas(tp)) 
-		tcp_vegas_enable(tp);
+	tcp_ca_event(tp, CA_EVENT_CWND_RESTART);
 
 	tp->snd_ssthresh = tcp_current_ssthresh(tp);
 	restart_cwnd = min(restart_cwnd, cwnd);
@@ -280,6 +279,10 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb)
 #define SYSCTL_FLAG_WSCALE	0x2
 #define SYSCTL_FLAG_SACK	0x4
 
+		/* If congestion control is doing timestamping */
+		if (tp->ca_ops->rtt_sample)
+			do_gettimeofday(&skb->stamp);
+
 		sysctl_flags = 0;
 		if (tcb->flags & TCPCB_FLAG_SYN) {
 			tcp_header_size = sizeof(struct tcphdr) + TCPOLEN_MSS;
@@ -304,17 +307,8 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb)
 					    (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK));
 		}
 		
-		/*
-		 * If the connection is idle and we are restarting,
-		 * then we don't want to do any Vegas calculations
-		 * until we get fresh RTT samples.  So when we
-		 * restart, we reset our Vegas state to a clean
-		 * slate. After we get acks for this flight of
-		 * packets, _then_ we can make Vegas calculations
-		 * again.
-		 */
-		if (tcp_is_vegas(tp) && tcp_packets_in_flight(tp) == 0)
-			tcp_vegas_enable(tp);
+		if (tcp_packets_in_flight(tp) == 0)
+			tcp_ca_event(tp, CA_EVENT_TX_START);
 
 		th = (struct tcphdr *) skb_push(skb, tcp_header_size);
 		skb->h.th = th;
@@ -521,6 +515,7 @@ static int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len)
 	 * skbs, which it never sent before. --ANK
 	 */
 	TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when;
+	buff->stamp = skb->stamp;
 
 	if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) {
 		tp->lost_out -= tcp_skb_pcount(skb);
@@ -1449,7 +1444,6 @@ static inline void tcp_connect_init(struct sock *sk)
 		tp->window_clamp = dst_metric(dst, RTAX_WINDOW);
 	tp->advmss = dst_metric(dst, RTAX_ADVMSS);
 	tcp_initialize_rcv_mss(sk);
-	tcp_ca_init(tp);
 
 	tcp_select_initial_window(tcp_full_space(sk),
 				  tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0),
@@ -1503,7 +1497,6 @@ int tcp_connect(struct sock *sk)
 	TCP_SKB_CB(buff)->end_seq = tp->write_seq;
 	tp->snd_nxt = tp->write_seq;
 	tp->pushed_seq = tp->write_seq;
-	tcp_ca_init(tp);
 
 	/* Send it off. */
 	TCP_SKB_CB(buff)->when = tcp_time_stamp;

net/ipv4/tcp_scalable.c

+/* Tom Kelly's Scalable TCP
+ *
+ * See htt://www-lce.eng.cam.ac.uk/~ctk21/scalable/
+ *
+ * John Heffner <jheffner@sc.edu>
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <net/tcp.h>
+
+/* These factors derived from the recommended values in the aer:
+ * .01 and and 7/8. We use 50 instead of 100 to account for
+ * delayed ack.
+ */
+#define TCP_SCALABLE_AI_CNT	50U
+#define TCP_SCALABLE_MD_SCALE	3
+
+static void tcp_scalable_cong_avoid(struct tcp_sock *tp, u32 ack, u32 rtt,
+				    u32 in_flight, int flag)
+{
+	if (in_flight < tp->snd_cwnd)
+		return;
+
+	if (tp->snd_cwnd <= tp->snd_ssthresh) {
+		tp->snd_cwnd++;
+	} else {
+		tp->snd_cwnd_cnt++;
+		if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)){
+			tp->snd_cwnd++;
+			tp->snd_cwnd_cnt = 0;
+		}
+	}
+	tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp);
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+}
+
+static u32 tcp_scalable_ssthresh(struct tcp_sock *tp)
+{
+	return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
+}
+
+
+static struct tcp_congestion_ops tcp_scalable = {
+	.ssthresh	= tcp_scalable_ssthresh,
+	.cong_avoid	= tcp_scalable_cong_avoid,
+	.min_cwnd	= tcp_reno_min_cwnd,
+
+	.owner		= THIS_MODULE,
+	.name		= "scalable",
+};
+
+static int __init tcp_scalable_register(void)
+{
+	return tcp_register_congestion_control(&tcp_scalable);
+}
+
+static void __exit tcp_scalable_unregister(void)
+{
+	tcp_unregister_congestion_control(&tcp_scalable);
+}
+
+module_init(tcp_scalable_register);
+module_exit(tcp_scalable_unregister);
+
+MODULE_AUTHOR("John Heffner");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Scalable TCP");

net/ipv4/tcp_vegas.c

+/*
+ * TCP Vegas congestion control
+ *
+ * This is based on the congestion detection/avoidance scheme described in
+ *    Lawrence S. Brakmo and Larry L. Peterson.
+ *    "TCP Vegas: End to end congestion avoidance on a global internet."
+ *    IEEE Journal on Selected Areas in Communication, 13(8):1465--1480,
+ *    October 1995. Available from:
+ *	ftp://ftp.cs.arizona.edu/xkernel/Papers/jsac.ps
+ *
+ * See http://www.cs.arizona.edu/xkernel/ for their implementation.
+ * The main aspects that distinguish this implementation from the
+ * Arizona Vegas implementation are:
+ *   o We do not change the loss detection or recovery mechanisms of
+ *     Linux in any way. Linux already recovers from losses quite well,
+ *     using fine-grained timers, NewReno, and FACK.
+ *   o To avoid the performance penalty imposed by increasing cwnd
+ *     only every-other RTT during slow start, we increase during
+ *     every RTT during slow start, just like Reno.
+ *   o Largely to allow continuous cwnd growth during slow start,
+ *     we use the rate at which ACKs come back as the "actual"
+ *     rate, rather than the rate at which data is sent.
+ *   o To speed convergence to the right rate, we set the cwnd
+ *     to achieve the right ("actual") rate when we exit slow start.
+ *   o To filter out the noise caused by delayed ACKs, we use the
+ *     minimum RTT sample observed during the last RTT to calculate
+ *     the actual rate.
+ *   o When the sender re-starts from idle, it waits until it has
+ *     received ACKs for an entire flight of new data before making
+ *     a cwnd adjustment decision. The original Vegas implementation
+ *     assumed senders never went idle.
+ */
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/tcp_diag.h>
+
+#include <net/tcp.h>
+
+/* Default values of the Vegas variables, in fixed-point representation
+ * with V_PARAM_SHIFT bits to the right of the binary point.
+ */
+#define V_PARAM_SHIFT 1
+static int alpha = 1<<V_PARAM_SHIFT;
+static int beta  = 3<<V_PARAM_SHIFT;
+static int gamma = 1<<V_PARAM_SHIFT;
+
+module_param(alpha, int, 0644);
+MODULE_PARM_DESC(alpha, "lower bound of packets in network (scale by 2)");
+module_param(beta, int, 0644);
+MODULE_PARM_DESC(beta, "upper bound of packets in network (scale by 2)");
+module_param(gamma, int, 0644);
+MODULE_PARM_DESC(gamma, "limit on increase (scale by 2)");
+
+
+/* Vegas variables */
+struct vegas {
+	u32	beg_snd_nxt;	/* right edge during last RTT */
+	u32	beg_snd_una;	/* left edge  during last RTT */
+	u32	beg_snd_cwnd;	/* saves the size of the cwnd */
+	u8	doing_vegas_now;/* if true, do vegas for this RTT */
+	u16	cntRTT;		/* # of RTTs measured within last RTT */
+	u32	minRTT;		/* min of RTTs measured within last RTT (in usec) */
+	u32	baseRTT;	/* the min of all Vegas RTT measurements seen (in usec) */
+};
+
+/* There are several situations when we must "re-start" Vegas:
+ *
+ *  o when a connection is established
+ *  o after an RTO
+ *  o after fast recovery
+ *  o when we send a packet and there is no outstanding
+ *    unacknowledged data (restarting an idle connection)
+ *
+ * In these circumstances we cannot do a Vegas calculation at the
+ * end of the first RTT, because any calculation we do is using
+ * stale info -- both the saved cwnd and congestion feedback are
+ * stale.
+ *
+ * Instead we must wait until the completion of an RTT during
+ * which we actually receive ACKs.
+ */
+static inline void vegas_enable(struct tcp_sock *tp)
+{
+	struct vegas *vegas = tcp_ca(tp);
+
+	/* Begin taking Vegas samples next time we send something. */
+	vegas->doing_vegas_now = 1;
+
+	/* Set the beginning of the next send window. */
+	vegas->beg_snd_nxt = tp->snd_nxt;
+
+	vegas->cntRTT = 0;
+	vegas->minRTT = 0x7fffffff;
+}
+
+/* Stop taking Vegas samples for now. */
+static inline void vegas_disable(struct tcp_sock *tp)
+{
+	struct vegas *vegas = tcp_ca(tp);
+
+	vegas->doing_vegas_now = 0;
+}
+
+static void tcp_vegas_init(struct tcp_sock *tp)
+{
+	struct vegas *vegas = tcp_ca(tp);
+
+	vegas->baseRTT = 0x7fffffff;
+	vegas_enable(tp);
+}
+
+/* Do RTT sampling needed for Vegas.
+ * Basically we:
+ *   o min-filter RTT samples from within an RTT to get the current
+ *     propagation delay + queuing delay (we are min-filtering to try to
+ *     avoid the effects of delayed ACKs)
+ *   o min-filter RTT samples from a much longer window (forever for now)
+ *     to find the propagation delay (baseRTT)
+ */
+static void tcp_vegas_rtt_calc(struct tcp_sock *tp, u32 usrtt)
+{
+	struct vegas *vegas = tcp_ca(tp);
+	u32 vrtt = usrtt + 1; /* Never allow zero rtt or baseRTT */
+
+	/* Filter to find propagation delay: */
+	if (vrtt < vegas->baseRTT)
+		vegas->baseRTT = vrtt;
+
+	/* Find the min RTT during the last RTT to find
+	 * the current prop. delay + queuing delay:
+	 */
+	vegas->minRTT = min(vegas->minRTT, vrtt);
+	vegas->cntRTT++;
+}
+
+static void tcp_vegas_state(struct tcp_sock *tp, u8 ca_state)
+{
+
+	if (ca_state == TCP_CA_Open)
+		vegas_enable(tp);
+	else
+		vegas_disable(tp);
+}
+
+/*
+ * If the connection is idle and we are restarting,
+ * then we don't want to do any Vegas calculations
+ * until we get fresh RTT samples.  So when we
+ * restart, we reset our Vegas state to a clean
+ * slate. After we get acks for this flight of
+ * packets, _then_ we can make Vegas calculations
+ * again.
+ */
+static void tcp_vegas_cwnd_event(struct tcp_sock *tp, enum tcp_ca_event event)
+{
+	if (event == CA_EVENT_CWND_RESTART ||
+	    event == CA_EVENT_TX_START)
+		tcp_vegas_init(tp);
+}
+
+static void tcp_vegas_cong_avoid(struct tcp_sock *tp, u32 ack,
+				 u32 seq_rtt, u32 in_flight, int flag)
+{
+	struct vegas *vegas = tcp_ca(tp);
+
+	if (!vegas->doing_vegas_now)
+		return tcp_reno_cong_avoid(tp, ack, seq_rtt, in_flight, flag);
+
+	/* The key players are v_beg_snd_una and v_beg_snd_nxt.
+	 *
+	 * These are so named because they represent the approximate values
+	 * of snd_una and snd_nxt at the beginning of the current RTT. More
+	 * precisely, they represent the amount of data sent during the RTT.
+	 * At the end of the RTT, when we receive an ACK for v_beg_snd_nxt,
+	 * we will calculate that (v_beg_snd_nxt - v_beg_snd_una) outstanding
+	 * bytes of data have been ACKed during the course of the RTT, giving
+	 * an "actual" rate of:
+	 *
+	 *     (v_beg_snd_nxt - v_beg_snd_una) / (rtt duration)
+	 *
+	 * Unfortunately, v_beg_snd_una is not exactly equal to snd_una,
+	 * because delayed ACKs can cover more than one segment, so they
+	 * don't line up nicely with the boundaries of RTTs.
+	 *
+	 * Another unfortunate fact of life is that delayed ACKs delay the
+	 * advance of the left edge of our send window, so that the number
+	 * of bytes we send in an RTT is often less than our cwnd will allow.
+	 * So we keep track of our cwnd separately, in v_beg_snd_cwnd.
+	 */
+
+	if (after(ack, vegas->beg_snd_nxt)) {
+		/* Do the Vegas once-per-RTT cwnd adjustment. */
+		u32 old_wnd, old_snd_cwnd;
+
+
+		/* Here old_wnd is essentially the window of data that was
+		 * sent during the previous RTT, and has all
+		 * been acknowledged in the course of the RTT that ended
+		 * with the ACK we just received. Likewise, old_snd_cwnd
+		 * is the cwnd during the previous RTT.
+		 */
+		old_wnd = (vegas->beg_snd_nxt - vegas->beg_snd_una) /
+			tp->mss_cache;
+		old_snd_cwnd = vegas->beg_snd_cwnd;
+
+		/* Save the extent of the current window so we can use this
+		 * at the end of the next RTT.
+		 */
+		vegas->beg_snd_una  = vegas->beg_snd_nxt;
+		vegas->beg_snd_nxt  = tp->snd_nxt;
+		vegas->beg_snd_cwnd = tp->snd_cwnd;
+
+		/* Take into account the current RTT sample too, to
+		 * decrease the impact of delayed acks. This double counts
+		 * this sample since we count it for the next window as well,
+		 * but that's not too awful, since we're taking the min,
+		 * rather than averaging.
+		 */
+		tcp_vegas_rtt_calc(tp, seq_rtt*1000);
+
+		/* We do the Vegas calculations only if we got enough RTT
+		 * samples that we can be reasonably sure that we got
+		 * at least one RTT sample that wasn't from a delayed ACK.
+		 * If we only had 2 samples total,
+		 * then that means we're getting only 1 ACK per RTT, which
+		 * means they're almost certainly delayed ACKs.
+		 * If  we have 3 samples, we should be OK.
+		 */
+
+		if (vegas->cntRTT <= 2) {
+			/* We don't have enough RTT samples to do the Vegas
+			 * calculation, so we'll behave like Reno.
+			 */
+			if (tp->snd_cwnd > tp->snd_ssthresh)
+				tp->snd_cwnd++;
+		} else {
+			u32 rtt, target_cwnd, diff;
+
+			/* We have enough RTT samples, so, using the Vegas
+			 * algorithm, we determine if we should increase or
+			 * decrease cwnd, and by how much.
+			 */
+
+			/* Pluck out the RTT we are using for the Vegas
+			 * calculations. This is the min RTT seen during the
+			 * last RTT. Taking the min filters out the effects
+			 * of delayed ACKs, at the cost of noticing congestion
+			 * a bit later.
+			 */
+			rtt = vegas->minRTT;
+
+			/* Calculate the cwnd we should have, if we weren't
+			 * going too fast.
+			 *
+			 * This is:
+			 *     (actual rate in segments) * baseRTT
+			 * We keep it as a fixed point number with
+			 * V_PARAM_SHIFT bits to the right of the binary point.
+			 */
+			target_cwnd = ((old_wnd * vegas->baseRTT)
+				       << V_PARAM_SHIFT) / rtt;
+
+			/* Calculate the difference between the window we had,
+			 * and the window we would like to have. This quantity
+			 * is the "Diff" from the Arizona Vegas papers.
+			 *
+			 * Again, this is a fixed point number with
+			 * V_PARAM_SHIFT bits to the right of the binary
+			 * point.
+			 */
+			diff = (old_wnd << V_PARAM_SHIFT) - target_cwnd;
+
+			if (tp->snd_cwnd < tp->snd_ssthresh) {
+				/* Slow start.  */
+				if (diff > gamma) {
+					/* Going too fast. Time to slow down
+					 * and switch to congestion avoidance.
+					 */
+					tp->snd_ssthresh = 2;
+
+					/* Set cwnd to match the actual rate
+					 * exactly:
+					 *   cwnd = (actual rate) * baseRTT
+					 * Then we add 1 because the integer
+					 * truncation robs us of full link
+					 * utilization.
+					 */
+					tp->snd_cwnd = min(tp->snd_cwnd,
+							   (target_cwnd >>
+							    V_PARAM_SHIFT)+1);
+
+				}
+			} else {
+				/* Congestion avoidance. */
+				u32 next_snd_cwnd;
+
+				/* Figure out where we would like cwnd
+				 * to be.
+				 */
+				if (diff > beta) {
+					/* The old window was too fast, so
+					 * we slow down.
+					 */
+					next_snd_cwnd = old_snd_cwnd - 1;
+				} else if (diff < alpha) {
+					/* We don't have enough extra packets
+					 * in the network, so speed up.
+					 */
+					next_snd_cwnd = old_snd_cwnd + 1;
+				} else {
+					/* Sending just as fast as we
+					 * should be.
+					 */
+					next_snd_cwnd = old_snd_cwnd;
+				}
+
+				/* Adjust cwnd upward or downward, toward the
+				 * desired value.
+				 */
+				if (next_snd_cwnd > tp->snd_cwnd)
+					tp->snd_cwnd++;
+				else if (next_snd_cwnd < tp->snd_cwnd)
+					tp->snd_cwnd--;
+			}
+		}
+
+		/* Wipe the slate clean for the next RTT. */
+		vegas->cntRTT = 0;
+		vegas->minRTT = 0x7fffffff;
+	}
+
+	/* The following code is executed for every ack we receive,
+	 * except for conditions checked in should_advance_cwnd()
+	 * before the call to tcp_cong_avoid(). Mainly this means that
+	 * we only execute this code if the ack actually acked some
+	 * data.
+	 */
+
+	/* If we are in slow start, increase our cwnd in response to this ACK.
+	 * (If we are not in slow start then we are in congestion avoidance,
+	 * and adjust our congestion window only once per RTT. See the code
+	 * above.)
+	 */
+	if (tp->snd_cwnd <= tp->snd_ssthresh)
+		tp->snd_cwnd++;
+
+	/* to keep cwnd from growing without bound */
+	tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp);
+
+	/* Make sure that we are never so timid as to reduce our cwnd below
+	 * 2 MSS.
+	 *
+	 * Going below 2 MSS would risk huge delayed ACKs from our receiver.
+	 */
+	tp->snd_cwnd = max(tp->snd_cwnd, 2U);
+}
+
+/* Extract info for Tcp socket info provided via netlink. */
+static void tcp_vegas_get_info(struct tcp_sock *tp, u32 ext,
+			       struct sk_buff *skb)
+{
+	const struct vegas *ca = tcp_ca(tp);
+	if (ext & (1<<(TCPDIAG_VEGASINFO-1))) {
+		struct tcpvegas_info *info;
+
+		info = RTA_DATA(__RTA_PUT(skb, TCPDIAG_VEGASINFO,
+					  sizeof(*info)));
+
+		info->tcpv_enabled = ca->doing_vegas_now;
+		info->tcpv_rttcnt = ca->cntRTT;
+		info->tcpv_rtt = ca->baseRTT;
+		info->tcpv_minrtt = ca->minRTT;
+	rtattr_failure:	;
+	}
+}
+
+static struct tcp_congestion_ops tcp_vegas = {
+	.init		= tcp_vegas_init,
+	.ssthresh	= tcp_reno_ssthresh,
+	.cong_avoid	= tcp_vegas_cong_avoid,
+	.min_cwnd	= tcp_reno_min_cwnd,
+	.rtt_sample	= tcp_vegas_rtt_calc,
+	.set_state	= tcp_vegas_state,
+	.cwnd_event	= tcp_vegas_cwnd_event,
+	.get_info	= tcp_vegas_get_info,
+
+	.owner		= THIS_MODULE,
+	.name		= "vegas",
+};
+
+static int __init tcp_vegas_register(void)
+{
+	BUG_ON(sizeof(struct vegas) > TCP_CA_PRIV_SIZE);
+	tcp_register_congestion_control(&tcp_vegas);
+	return 0;
+}
+
+static void __exit tcp_vegas_unregister(void)
+{
+	tcp_unregister_congestion_control(&tcp_vegas);
+}
+
+module_init(tcp_vegas_register);
+module_exit(tcp_vegas_unregister);
+
+MODULE_AUTHOR("Stephen Hemminger");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("TCP Vegas");

net/ipv4/tcp_westwood.c

+/*
+ * TCP Westwood+
+ *
+ *	Angelo Dell'Aera:	TCP Westwood+ support
+ */
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/tcp_diag.h>
+#include <net/tcp.h>
+
+/* TCP Westwood structure */
+struct westwood {
+	u32    bw_ns_est;        /* first bandwidth estimation..not too smoothed 8) */
+	u32    bw_est;           /* bandwidth estimate */
+	u32    rtt_win_sx;       /* here starts a new evaluation... */
+	u32    bk;
+	u32    snd_una;          /* used for evaluating the number of acked bytes */
+	u32    cumul_ack;
+	u32    accounted;
+	u32    rtt;
+	u32    rtt_min;          /* minimum observed RTT */
+};
+
+
+/* TCP Westwood functions and constants */
+#define TCP_WESTWOOD_RTT_MIN   (HZ/20)	/* 50ms */
+#define TCP_WESTWOOD_INIT_RTT  (20*HZ)	/* maybe too conservative?! */
+
+/*
+ * @tcp_westwood_create
+ * This function initializes fields used in TCP Westwood+,
+ * it is called after the initial SYN, so the sequence numbers
+ * are correct but new passive connections we have no
+ * information about RTTmin at this time so we simply set it to
+ * TCP_WESTWOOD_INIT_RTT. This value was chosen to be too conservative
+ * since in this way we're sure it will be updated in a consistent
+ * way as soon as possible. It will reasonably happen within the first
+ * RTT period of the connection lifetime.
+ */
+static void tcp_westwood_init(struct tcp_sock *tp)
+{
+	struct westwood *w = tcp_ca(tp);
+
+	w->bk = 0;
+        w->bw_ns_est = 0;
+        w->bw_est = 0;
+        w->accounted = 0;
+        w->cumul_ack = 0;
+	w->rtt_min = w->rtt = TCP_WESTWOOD_INIT_RTT;
+	w->rtt_win_sx = tcp_time_stamp;
+	w->snd_una = tp->snd_una;
+}
+
+/*
+ * @westwood_do_filter
+ * Low-pass filter. Implemented using constant coefficients.
+ */
+static inline u32 westwood_do_filter(u32 a, u32 b)
+{
+	return (((7 * a) + b) >> 3);
+}
+
+static inline void westwood_filter(struct westwood *w, u32 delta)
+{
+	w->bw_ns_est = westwood_do_filter(w->bw_ns_est, w->bk / delta);
+	w->bw_est = westwood_do_filter(w->bw_est, w->bw_ns_est);
+}
+
+/*
+ * @westwood_pkts_acked
+ * Called after processing group of packets.
+ * but all westwood needs is the last sample of srtt.
+ */
+static void tcp_westwood_pkts_acked(struct tcp_sock *tp, u32 cnt)
+{
+	struct westwood *w = tcp_ca(tp);
+	if (cnt > 0)
+		w->rtt = tp->srtt >> 3;
+}
+
+/*
+ * @westwood_update_window
+ * It updates RTT evaluation window if it is the right moment to do
+ * it. If so it calls filter for evaluating bandwidth.
+ */
+static void westwood_update_window(struct tcp_sock *tp)
+{
+	struct westwood *w = tcp_ca(tp);
+	s32 delta = tcp_time_stamp - w->rtt_win_sx;
+
+	/*
+	 * See if a RTT-window has passed.
+	 * Be careful since if RTT is less than
+	 * 50ms we don't filter but we continue 'building the sample'.
+	 * This minimum limit was chosen since an estimation on small
+	 * time intervals is better to avoid...
+	 * Obviously on a LAN we reasonably will always have
+	 * right_bound = left_bound + WESTWOOD_RTT_MIN
+	 */
+	if (w->rtt && delta > max_t(u32, w->rtt, TCP_WESTWOOD_RTT_MIN)) {
+		westwood_filter(w, delta);
+
+		w->bk = 0;
+		w->rtt_win_sx = tcp_time_stamp;
+	}
+}
+
+/*
+ * @westwood_fast_bw
+ * It is called when we are in fast path. In particular it is called when
+ * header prediction is successful. In such case in fact update is
+ * straight forward and doesn't need any particular care.
+ */
+static inline void westwood_fast_bw(struct tcp_sock *tp)
+{
+	struct westwood *w = tcp_ca(tp);
+
+	westwood_update_window(tp);
+
+	w->bk += tp->snd_una - w->snd_una;
+	w->snd_una = tp->snd_una;
+	w->rtt_min = min(w->rtt, w->rtt_min);
+}
+
+/*
+ * @westwood_acked_count
+ * This function evaluates cumul_ack for evaluating bk in case of
+ * delayed or partial acks.
+ */
+static inline u32 westwood_acked_count(struct tcp_sock *tp)
+{
+	struct westwood *w = tcp_ca(tp);
+
+	w->cumul_ack = tp->snd_una - w->snd_una;
+
+        /* If cumul_ack is 0 this is a dupack since it's not moving
+         * tp->snd_una.
+         */
+        if (!w->cumul_ack) {
+		w->accounted += tp->mss_cache;
+		w->cumul_ack = tp->mss_cache;
+	}
+
+        if (w->cumul_ack > tp->mss_cache) {
+		/* Partial or delayed ack */
+		if (w->accounted >= w->cumul_ack) {
+			w->accounted -= w->cumul_ack;
+			w->cumul_ack = tp->mss_cache;
+		} else {
+			w->cumul_ack -= w->accounted;
+			w->accounted = 0;
+		}
+	}
+
+	w->snd_una = tp->snd_una;
+
+	return w->cumul_ack;
+}
+
+static inline u32 westwood_bw_rttmin(const struct tcp_sock *tp)
+{
+	struct westwood *w = tcp_ca(tp);
+	return max_t(u32, (w->bw_est * w->rtt_min) / tp->mss_cache, 2);
+}
+
+/*
+ * TCP Westwood
+ * Here limit is evaluated as Bw estimation*RTTmin (for obtaining it
+ * in packets we use mss_cache). Rttmin is guaranteed to be >= 2
+ * so avoids ever returning 0.
+ */
+static u32 tcp_westwood_cwnd_min(struct tcp_sock *tp)
+{
+	return westwood_bw_rttmin(tp);
+}
+
+static void tcp_westwood_event(struct tcp_sock *tp, enum tcp_ca_event event)
+{
+	struct westwood *w = tcp_ca(tp);
+
+	switch(event) {
+	case CA_EVENT_FAST_ACK:
+		westwood_fast_bw(tp);
+		break;
+
+	case CA_EVENT_COMPLETE_CWR:
+		tp->snd_cwnd = tp->snd_ssthresh = westwood_bw_rttmin(tp);
+		break;
+
+	case CA_EVENT_FRTO:
+		tp->snd_ssthresh = westwood_bw_rttmin(tp);
+		break;
+
+	case CA_EVENT_SLOW_ACK:
+		westwood_update_window(tp);
+		w->bk += westwood_acked_count(tp);
+		w->rtt_min = min(w->rtt, w->rtt_min);
+		break;
+
+	default:
+		/* don't care */
+		break;
+	}
+}
+
+
+/* Extract info for Tcp socket info provided via netlink. */
+static void tcp_westwood_info(struct tcp_sock *tp, u32 ext,
+			      struct sk_buff *skb)
+{
+	const struct westwood *ca = tcp_ca(tp);
+	if (ext & (1<<(TCPDIAG_VEGASINFO-1))) {
+		struct rtattr *rta;
+		struct tcpvegas_info *info;
+
+		rta = __RTA_PUT(skb, TCPDIAG_VEGASINFO, sizeof(*info));
+		info = RTA_DATA(rta);
+		info->tcpv_enabled = 1;
+		info->tcpv_rttcnt = 0;
+		info->tcpv_rtt = jiffies_to_usecs(ca->rtt);
+		info->tcpv_minrtt = jiffies_to_usecs(ca->rtt_min);
+	rtattr_failure:	;
+	}
+}
+
+
+static struct tcp_congestion_ops tcp_westwood = {
+	.init		= tcp_westwood_init,
+	.ssthresh	= tcp_reno_ssthresh,
+	.cong_avoid	= tcp_reno_cong_avoid,
+	.min_cwnd	= tcp_westwood_cwnd_min,
+	.cwnd_event	= tcp_westwood_event,
+	.get_info	= tcp_westwood_info,
+	.pkts_acked	= tcp_westwood_pkts_acked,
+
+	.owner		= THIS_MODULE,
+	.name		= "westwood"
+};
+
+static int __init tcp_westwood_register(void)
+{
+	BUG_ON(sizeof(struct westwood) > TCP_CA_PRIV_SIZE);
+	return tcp_register_congestion_control(&tcp_westwood);
+}
+
+static void __exit tcp_westwood_unregister(void)
+{
+	tcp_unregister_congestion_control(&tcp_westwood);
+}
+
+module_init(tcp_westwood_register);
+module_exit(tcp_westwood_unregister);
+
+MODULE_AUTHOR("Stephen Hemminger, Angelo Dell'Aera");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("TCP Westwood+");

net/ipv6/tcp_ipv6.c

@@ -2025,7 +2025,7 @@ static int tcp_v6_init_sock(struct sock *sk)
 	sk->sk_state = TCP_CLOSE;
 
 	tp->af_specific = &ipv6_specific;
-
+	tp->ca_ops = &tcp_reno;
 	sk->sk_write_space = sk_stream_write_space;
 	sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);