NAME

tcp_congctl — TCP congestion control API

SYNOPSIS

#include <netinet/tcp_congctl.h>

int
tcp_congctl_register(const char *, struct tcp_congctl *);

int
tcp_congctl_unregister(const char *);

DESCRIPTION

The tcp_congctrl API is used to add or remove TCP congestion control algorithms on-the-fly and to modularize them. It includes basically two functions:

tcp_congctl_register(const char *, struct tcp_congctl *)

Registers a new congestion control algorithm. The struct tcp_congctl argument must contain a list of callbacks like the following:

struct tcp_congctl {
	int  (*fast_retransmit)(struct tcpcb *,
	    struct tcphdr *);
	void (*slow_retransmit)(struct tcpcb *);
	void (*fast_retransmit_newack)(struct tcpcb *,
	    struct tcphdr *);
	void (*newack)(struct tcpcb *,
	    struct tcphdr *);
	void (*cong_exp)(struct tcpcb *);
};

tcp_congctl_unregister(const char *)

If found, unregister the selected TCP congestion control algorithm.

RETURN VALUES

tcp_congctl_register() and tcp_congctl_unregister() both return 0 when there is no error. If the name is already registered, tcp_congctl_register() will return EEXIST. tcp_congctl_unregister() can return ENOENT if there is no congestion control algorithm by that name and can return EBUSY if the matched algorithm is being used by userspace applications.

FILES

Implementation is in sys/netinet/tcp_congctl.c and the interface is in sys/netinet/tcp_congctl.h.

SEE ALSO

tcp(4)