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[TCP]: Add pluggable congestion control algorithm infrastructure. 

Allow TCP to have multiple pluggable congestion control algorithms.
Algorithms are defined by a set of operations and can be built in
or modules.  The legacy "new RENO" algorithm is used as a starting
point and fallback.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stephen Hemminger 2005-06-23 12:19:55 -07:00 committed by David S. Miller
parent a8ad86f2dc
commit 317a76f9a4
13 changed files with 399 additions and 999 deletions
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9
include/linux/sysctl.h
View File

@ -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 {

49
include/linux/tcp.h
View File

@ -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 */

237
include/net/tcp.h
View File

@ -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 */

3
net/ipv4/Makefile
View File

@ -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

114
net/ipv4/sysctl_net_ipv4.c
View File

@ -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 }
};

2
net/ipv4/tcp.c
View File

@ -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);

195
net/ipv4/tcp_cong.c Normal file
View File

@ -0,0 +1,195 @@
/*
* 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);

20
net/ipv4/tcp_diag.c
View File

@ -42,7 +42,6 @@ struct tcpdiag_entry
static struct sock *tcpnl;
#define TCPDIAG_PUT(skb, attrtype, attrlen) \
({ int rtalen = RTA_LENGTH(attrlen); \
struct rtattr *rta; \
@ -61,7 +60,6 @@ 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 +71,6 @@ 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));
}
r->tcpdiag_family = sk->sk_family;
r->tcpdiag_state = sk->sk_state;
@ -166,19 +161,8 @@ 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;

737
net/ipv4/tcp_input.c
View File

@ -61,7 +61,6 @@
* Panu Kuhlberg: Experimental audit of TCP (re)transmission
* engine. Lots of bugs are found.
* Pasi Sarolahti: F-RTO for dealing with spurious RTOs
* Angelo Dell'Aera: TCP Westwood+ support
*/
#include <linux/config.h>
@ -88,23 +87,9 @@ int sysctl_tcp_rfc1337;
int sysctl_tcp_max_orphans = NR_FILE;
int sysctl_tcp_frto;
int sysctl_tcp_nometrics_save;
int sysctl_tcp_westwood;
int sysctl_tcp_vegas_cong_avoid;
int sysctl_tcp_moderate_rcvbuf = 1;
/* 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
int sysctl_tcp_vegas_alpha = 1<<V_PARAM_SHIFT;
int sysctl_tcp_vegas_beta = 3<<V_PARAM_SHIFT;
int sysctl_tcp_vegas_gamma = 1<<V_PARAM_SHIFT;
int sysctl_tcp_bic = 1;
int sysctl_tcp_bic_fast_convergence = 1;
int sysctl_tcp_bic_low_window = 14;
int sysctl_tcp_bic_beta = 819; /* = 819/1024 (BICTCP_BETA_SCALE) */
#define FLAG_DATA 0x01 /* Incoming frame contained data. */
#define FLAG_WIN_UPDATE 0x02 /* Incoming ACK was a window update. */
#define FLAG_DATA_ACKED 0x04 /* This ACK acknowledged new data. */
@ -333,15 +318,6 @@ static void tcp_init_buffer_space(struct sock *sk)
tp->snd_cwnd_stamp = tcp_time_stamp;
}
static void init_bictcp(struct tcp_sock *tp)
{
tp->bictcp.cnt = 0;
tp->bictcp.last_max_cwnd = 0;
tp->bictcp.last_cwnd = 0;
tp->bictcp.last_stamp = 0;
}
/* 5. Recalculate window clamp after socket hit its memory bounds. */
static void tcp_clamp_window(struct sock *sk, struct tcp_sock *tp)
{
@ -558,45 +534,6 @@ static void tcp_event_data_recv(struct sock *sk, struct tcp_sock *tp, struct sk_
tcp_grow_window(sk, tp, skb);
}
/* When starting a new connection, pin down the current choice of
* congestion algorithm.
*/
void tcp_ca_init(struct tcp_sock *tp)
{
if (sysctl_tcp_westwood)
tp->adv_cong = TCP_WESTWOOD;
else if (sysctl_tcp_bic)
tp->adv_cong = TCP_BIC;
else if (sysctl_tcp_vegas_cong_avoid) {
tp->adv_cong = TCP_VEGAS;
tp->vegas.baseRTT = 0x7fffffff;
tcp_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 inline void vegas_rtt_calc(struct tcp_sock *tp, __u32 rtt)
{
__u32 vrtt = rtt + 1; /* Never allow zero rtt or baseRTT */
/* Filter to find propagation delay: */
if (vrtt < tp->vegas.baseRTT)
tp->vegas.baseRTT = vrtt;
/* Find the min RTT during the last RTT to find
* the current prop. delay + queuing delay:
*/
tp->vegas.minRTT = min(tp->vegas.minRTT, vrtt);
tp->vegas.cntRTT++;
}
/* Called to compute a smoothed rtt estimate. The data fed to this
* routine either comes from timestamps, or from segments that were
* known _not_ to have been retransmitted [see Karn/Partridge
@ -606,13 +543,10 @@ static inline void vegas_rtt_calc(struct tcp_sock *tp, __u32 rtt)
* To save cycles in the RFC 1323 implementation it was better to break
* it up into three procedures. -- erics
*/
static void tcp_rtt_estimator(struct tcp_sock *tp, __u32 mrtt)
static void tcp_rtt_estimator(struct tcp_sock *tp, __u32 mrtt, u32 *usrtt)
{
long m = mrtt; /* RTT */
if (tcp_vegas_enabled(tp))
vegas_rtt_calc(tp, mrtt);
/* The following amusing code comes from Jacobson's
* article in SIGCOMM '88. Note that rtt and mdev
* are scaled versions of rtt and mean deviation.
@ -670,7 +604,8 @@ static void tcp_rtt_estimator(struct tcp_sock *tp, __u32 mrtt)
tp->rtt_seq = tp->snd_nxt;
}
tcp_westwood_update_rtt(tp, tp->srtt >> 3);
if (tp->ca_ops->rtt_sample)
tp->ca_ops->rtt_sample(tp, *usrtt);
}
/* Calculate rto without backoff. This is the second half of Van Jacobson's
@ -1185,8 +1120,8 @@ void tcp_enter_frto(struct sock *sk)
tp->snd_una == tp->high_seq ||
(tp->ca_state == TCP_CA_Loss && !tp->retransmits)) {
tp->prior_ssthresh = tcp_current_ssthresh(tp);
if (!tcp_westwood_ssthresh(tp))
tp->snd_ssthresh = tcp_recalc_ssthresh(tp);
tp->snd_ssthresh = tp->ca_ops->ssthresh(tp);
tcp_ca_event(tp, CA_EVENT_FRTO);
}
/* Have to clear retransmission markers here to keep the bookkeeping
@ -1252,8 +1187,6 @@ static void tcp_enter_frto_loss(struct sock *sk)
tcp_set_ca_state(tp, TCP_CA_Loss);
tp->high_seq = tp->frto_highmark;
TCP_ECN_queue_cwr(tp);
init_bictcp(tp);
}
void tcp_clear_retrans(struct tcp_sock *tp)
@ -1283,7 +1216,8 @@ void tcp_enter_loss(struct sock *sk, int how)
if (tp->ca_state <= TCP_CA_Disorder || tp->snd_una == tp->high_seq ||
(tp->ca_state == TCP_CA_Loss && !tp->retransmits)) {
tp->prior_ssthresh = tcp_current_ssthresh(tp);
tp->snd_ssthresh = tcp_recalc_ssthresh(tp);
tp->snd_ssthresh = tp->ca_ops->ssthresh(tp);
tcp_ca_event(tp, CA_EVENT_LOSS);
}
tp->snd_cwnd = 1;
tp->snd_cwnd_cnt = 0;
@ -1596,28 +1530,14 @@ static inline void tcp_moderate_cwnd(struct tcp_sock *tp)
}
/* Decrease cwnd each second ack. */
static void tcp_cwnd_down(struct tcp_sock *tp)
{
int decr = tp->snd_cwnd_cnt + 1;
__u32 limit;
/*
* TCP Westwood
* Here limit is evaluated as BWestimation*RTTmin (for obtaining it
* in packets we use mss_cache). If sysctl_tcp_westwood is off
* tcp_westwood_bw_rttmin() returns 0. In such case snd_ssthresh is
* still used as usual. It prevents other strange cases in which
* BWE*RTTmin could assume value 0. It should not happen but...
*/
if (!(limit = tcp_westwood_bw_rttmin(tp)))
limit = tp->snd_ssthresh/2;
tp->snd_cwnd_cnt = decr&1;
decr >>= 1;
if (decr && tp->snd_cwnd > limit)
if (decr && tp->snd_cwnd > tp->ca_ops->min_cwnd(tp))
tp->snd_cwnd -= decr;
tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp)+1);
@ -1654,8 +1574,8 @@ static void DBGUNDO(struct sock *sk, struct tcp_sock *tp, const char *msg)
static void tcp_undo_cwr(struct tcp_sock *tp, int undo)
{
if (tp->prior_ssthresh) {
if (tcp_is_bic(tp))
tp->snd_cwnd = max(tp->snd_cwnd, tp->bictcp.last_max_cwnd);
if (tp->ca_ops->undo_cwnd)
tp->snd_cwnd = tp->ca_ops->undo_cwnd(tp);
else
tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh<<1);
@ -1767,11 +1687,9 @@ static int tcp_try_undo_loss(struct sock *sk, struct tcp_sock *tp)
static inline void tcp_complete_cwr(struct tcp_sock *tp)
{
if (tcp_westwood_cwnd(tp))
tp->snd_ssthresh = tp->snd_cwnd;
else
tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
tp->snd_cwnd_stamp = tcp_time_stamp;
tcp_ca_event(tp, CA_EVENT_COMPLETE_CWR);
}
static void tcp_try_to_open(struct sock *sk, struct tcp_sock *tp, int flag)
@ -1946,7 +1864,7 @@ tcp_fastretrans_alert(struct sock *sk, u32 prior_snd_una,
if (tp->ca_state < TCP_CA_CWR) {
if (!(flag&FLAG_ECE))
tp->prior_ssthresh = tcp_current_ssthresh(tp);
tp->snd_ssthresh = tcp_recalc_ssthresh(tp);
tp->snd_ssthresh = tp->ca_ops->ssthresh(tp);
TCP_ECN_queue_cwr(tp);
}
@ -1963,7 +1881,7 @@ tcp_fastretrans_alert(struct sock *sk, u32 prior_snd_una,
/* Read draft-ietf-tcplw-high-performance before mucking
* with this code. (Superceeds RFC1323)
*/
static void tcp_ack_saw_tstamp(struct tcp_sock *tp, int flag)
static void tcp_ack_saw_tstamp(struct tcp_sock *tp, u32 *usrtt, int flag)
{
__u32 seq_rtt;
@ -1983,13 +1901,13 @@ static void tcp_ack_saw_tstamp(struct tcp_sock *tp, int flag)
* in window is lost... Voila. --ANK (010210)
*/
seq_rtt = tcp_time_stamp - tp->rx_opt.rcv_tsecr;
tcp_rtt_estimator(tp, seq_rtt);
tcp_rtt_estimator(tp, seq_rtt, usrtt);
tcp_set_rto(tp);
tp->backoff = 0;
tcp_bound_rto(tp);
}
static void tcp_ack_no_tstamp(struct tcp_sock *tp, u32 seq_rtt, int flag)
static void tcp_ack_no_tstamp(struct tcp_sock *tp, u32 seq_rtt, u32 *usrtt, int flag)
{
/* We don't have a timestamp. Can only use
* packets that are not retransmitted to determine
@ -2003,338 +1921,29 @@ static void tcp_ack_no_tstamp(struct tcp_sock *tp, u32 seq_rtt, int flag)
if (flag & FLAG_RETRANS_DATA_ACKED)
return;
tcp_rtt_estimator(tp, seq_rtt);
tcp_rtt_estimator(tp, seq_rtt, usrtt);
tcp_set_rto(tp);
tp->backoff = 0;
tcp_bound_rto(tp);
}
static inline void tcp_ack_update_rtt(struct tcp_sock *tp,
int flag, s32 seq_rtt)
int flag, s32 seq_rtt, u32 *usrtt)
{
/* Note that peer MAY send zero echo. In this case it is ignored. (rfc1323) */
if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
tcp_ack_saw_tstamp(tp, flag);
tcp_ack_saw_tstamp(tp, usrtt, flag);
else if (seq_rtt >= 0)
tcp_ack_no_tstamp(tp, seq_rtt, flag);
tcp_ack_no_tstamp(tp, seq_rtt, usrtt, flag);
}
/*
* Compute congestion window to use.
*
* This is from the implementation of BICTCP in
* Lison-Xu, Kahaled Harfoush, and Injog 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.
*/
static inline __u32 bictcp_cwnd(struct tcp_sock *tp)
static inline void tcp_cong_avoid(struct tcp_sock *tp, u32 ack, u32 rtt,
u32 in_flight, int good)
{
/* orignal Reno behaviour */
if (!tcp_is_bic(tp))
return tp->snd_cwnd;
if (tp->bictcp.last_cwnd == tp->snd_cwnd &&
(s32)(tcp_time_stamp - tp->bictcp.last_stamp) <= (HZ>>5))
return tp->bictcp.cnt;
tp->bictcp.last_cwnd = tp->snd_cwnd;
tp->bictcp.last_stamp = tcp_time_stamp;
/* start off normal */
if (tp->snd_cwnd <= sysctl_tcp_bic_low_window)
tp->bictcp.cnt = tp->snd_cwnd;
/* binary increase */
else if (tp->snd_cwnd < tp->bictcp.last_max_cwnd) {
__u32 dist = (tp->bictcp.last_max_cwnd - tp->snd_cwnd)
/ BICTCP_B;
if (dist > BICTCP_MAX_INCREMENT)
/* linear increase */
tp->bictcp.cnt = tp->snd_cwnd / BICTCP_MAX_INCREMENT;
else if (dist <= 1U)
/* binary search increase */
tp->bictcp.cnt = tp->snd_cwnd * BICTCP_FUNC_OF_MIN_INCR
/ BICTCP_B;
else
/* binary search increase */
tp->bictcp.cnt = tp->snd_cwnd / dist;
} else {
/* slow start amd linear increase */
if (tp->snd_cwnd < tp->bictcp.last_max_cwnd + BICTCP_B)
/* slow start */
tp->bictcp.cnt = tp->snd_cwnd * BICTCP_FUNC_OF_MIN_INCR
/ BICTCP_B;
else if (tp->snd_cwnd < tp->bictcp.last_max_cwnd
+ BICTCP_MAX_INCREMENT*(BICTCP_B-1))
/* slow start */
tp->bictcp.cnt = tp->snd_cwnd * (BICTCP_B-1)
/ (tp->snd_cwnd-tp->bictcp.last_max_cwnd);
else
/* linear increase */
tp->bictcp.cnt = tp->snd_cwnd / BICTCP_MAX_INCREMENT;
}
return tp->bictcp.cnt;
}
/* This is Jacobson's slow start and congestion avoidance.
* SIGCOMM '88, p. 328.
*/
static inline void reno_cong_avoid(struct tcp_sock *tp)
{
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 >= bictcp_cwnd(tp)) {
if (tp->snd_cwnd < tp->snd_cwnd_clamp)
tp->snd_cwnd++;
tp->snd_cwnd_cnt=0;
} else
tp->snd_cwnd_cnt++;
}
tp->ca_ops->cong_avoid(tp, ack, rtt, in_flight, good);
tp->snd_cwnd_stamp = tcp_time_stamp;
}
/* 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.
*/
static void vegas_cong_avoid(struct tcp_sock *tp, u32 ack, u32 seq_rtt)
{
/* 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, tp->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 = (tp->vegas.beg_snd_nxt - tp->vegas.beg_snd_una) /
tp->mss_cache_std;
old_snd_cwnd = tp->vegas.beg_snd_cwnd;
/* Save the extent of the current window so we can use this
* at the end of the next RTT.
*/
tp->vegas.beg_snd_una = tp->vegas.beg_snd_nxt;
tp->vegas.beg_snd_nxt = tp->snd_nxt;
tp->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.
*/
vegas_rtt_calc(tp, seq_rtt);
/* 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 (tp->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 = tp->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 * tp->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 > sysctl_tcp_vegas_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 > sysctl_tcp_vegas_beta) {
/* The old window was too fast, so
* we slow down.
*/
next_snd_cwnd = old_snd_cwnd - 1;
} else if (diff < sysctl_tcp_vegas_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. */
tp->vegas.cntRTT = 0;
tp->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);
tp->snd_cwnd_stamp = tcp_time_stamp;
}
static inline void tcp_cong_avoid(struct tcp_sock *tp, u32 ack, u32 seq_rtt)
{
if (tcp_vegas_enabled(tp))
vegas_cong_avoid(tp, ack, seq_rtt);
else
reno_cong_avoid(tp);
}
/* Restart timer after forward progress on connection.
* RFC2988 recommends to restart timer to now+rto.
*/
@ -2415,13 +2024,18 @@ static int tcp_tso_acked(struct sock *sk, struct sk_buff *skb,
/* Remove acknowledged frames from the retransmission queue. */
static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p)
static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p, s32 *seq_usrtt)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
__u32 now = tcp_time_stamp;
int acked = 0;
__s32 seq_rtt = -1;
struct timeval usnow;
u32 pkts_acked = 0;
if (seq_usrtt)
do_gettimeofday(&usnow);
while ((skb = skb_peek(&sk->sk_write_queue)) &&
skb != sk->sk_send_head) {
@ -2448,6 +2062,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p)
*/
if (!(scb->flags & TCPCB_FLAG_SYN)) {
acked |= FLAG_DATA_ACKED;
++pkts_acked;
} else {
acked |= FLAG_SYN_ACKED;
tp->retrans_stamp = 0;
@ -2461,6 +2076,10 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p)
seq_rtt = -1;
} else if (seq_rtt < 0)
seq_rtt = now - scb->when;
if (seq_usrtt)
*seq_usrtt = (usnow.tv_sec - skb->stamp.tv_sec) * 1000000
+ (usnow.tv_usec - skb->stamp.tv_usec);
if (sacked & TCPCB_SACKED_ACKED)
tp->sacked_out -= tcp_skb_pcount(skb);
if (sacked & TCPCB_LOST)
@ -2479,8 +2098,11 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p)
}
if (acked&FLAG_ACKED) {
tcp_ack_update_rtt(tp, acked, seq_rtt);
tcp_ack_update_rtt(tp, acked, seq_rtt, seq_usrtt);
tcp_ack_packets_out(sk, tp);
if (tp->ca_ops->pkts_acked)
tp->ca_ops->pkts_acked(tp, pkts_acked);
}
#if FASTRETRANS_DEBUG > 0
@ -2624,257 +2246,6 @@ static void tcp_process_frto(struct sock *sk, u32 prior_snd_una)
tp->frto_counter = (tp->frto_counter + 1) % 3;
}
/*
* TCP Westwood+
*/
/*
* @init_westwood
* This function initializes fields used in TCP Westwood+. We can't
* get 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 init_westwood(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
tp->westwood.bw_ns_est = 0;
tp->westwood.bw_est = 0;
tp->westwood.accounted = 0;
tp->westwood.cumul_ack = 0;
tp->westwood.rtt_win_sx = tcp_time_stamp;
tp->westwood.rtt = TCP_WESTWOOD_INIT_RTT;
tp->westwood.rtt_min = TCP_WESTWOOD_INIT_RTT;
tp->westwood.snd_una = tp->snd_una;
}
/*
* @westwood_do_filter
* Low-pass filter. Implemented using constant coeffients.
*/
static inline __u32 westwood_do_filter(__u32 a, __u32 b)
{
return (((7 * a) + b) >> 3);
}
static void westwood_filter(struct sock *sk, __u32 delta)
{
struct tcp_sock *tp = tcp_sk(sk);
tp->westwood.bw_ns_est =
westwood_do_filter(tp->westwood.bw_ns_est,
tp->westwood.bk / delta);
tp->westwood.bw_est =
westwood_do_filter(tp->westwood.bw_est,
tp->westwood.bw_ns_est);
}
/*
* @westwood_update_rttmin
* It is used to update RTTmin. In this case we MUST NOT use
* WESTWOOD_RTT_MIN minimum bound since we could be on a LAN!
*/
static inline __u32 westwood_update_rttmin(const struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
__u32 rttmin = tp->westwood.rtt_min;
if (tp->westwood.rtt != 0 &&
(tp->westwood.rtt < tp->westwood.rtt_min || !rttmin))
rttmin = tp->westwood.rtt;
return rttmin;
}
/*
* @westwood_acked
* Evaluate increases for dk.
*/
static inline __u32 westwood_acked(const struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
return tp->snd_una - tp->westwood.snd_una;
}
/*
* @westwood_new_window
* It evaluates if we are receiving data inside the same RTT window as
* when we started.
* Return value:
* It returns 0 if we are still evaluating samples in the same RTT
* window, 1 if the sample has to be considered in the next window.
*/
static int westwood_new_window(const struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
__u32 left_bound;
__u32 rtt;
int ret = 0;
left_bound = tp->westwood.rtt_win_sx;
rtt = max(tp->westwood.rtt, (u32) TCP_WESTWOOD_RTT_MIN);
/*
* 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 choosen since an estimation on small
* time intervals is better to avoid...
* Obvioulsy on a LAN we reasonably will always have
* right_bound = left_bound + WESTWOOD_RTT_MIN
*/
if ((left_bound + rtt) < tcp_time_stamp)
ret = 1;
return ret;
}
/*
* @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 sock *sk, __u32 now)
{
struct tcp_sock *tp = tcp_sk(sk);
__u32 delta = now - tp->westwood.rtt_win_sx;
if (delta) {
if (tp->westwood.rtt)
westwood_filter(sk, delta);
tp->westwood.bk = 0;
tp->westwood.rtt_win_sx = tcp_time_stamp;
}
}
static void westwood_update_window(struct sock *sk, __u32 now)
{
if (westwood_new_window(sk))
__westwood_update_window(sk, now);
}
/*
* @__tcp_westwood_fast_bw
* It is called when we are in fast path. In particular it is called when
* header prediction is successfull. In such case infact update is
* straight forward and doesn't need any particular care.
*/
static void __tcp_westwood_fast_bw(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
westwood_update_window(sk, tcp_time_stamp);
tp->westwood.bk += westwood_acked(sk);
tp->westwood.snd_una = tp->snd_una;
tp->westwood.rtt_min = westwood_update_rttmin(sk);
}
static inline void tcp_westwood_fast_bw(struct sock *sk, struct sk_buff *skb)
{
if (tcp_is_westwood(tcp_sk(sk)))
__tcp_westwood_fast_bw(sk, skb);
}
/*
* @westwood_dupack_update
* It updates accounted and cumul_ack when receiving a dupack.
*/
static void westwood_dupack_update(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
tp->westwood.accounted += tp->mss_cache_std;
tp->westwood.cumul_ack = tp->mss_cache_std;
}
static inline int westwood_may_change_cumul(struct tcp_sock *tp)
{
return (tp->westwood.cumul_ack > tp->mss_cache_std);
}
static inline void westwood_partial_update(struct tcp_sock *tp)
{
tp->westwood.accounted -= tp->westwood.cumul_ack;
tp->westwood.cumul_ack = tp->mss_cache_std;
}
static inline void westwood_complete_update(struct tcp_sock *tp)
{
tp->westwood.cumul_ack -= tp->westwood.accounted;
tp->westwood.accounted = 0;
}
/*
* @westwood_acked_count
* This function evaluates cumul_ack for evaluating dk in case of
* delayed or partial acks.
*/
static inline __u32 westwood_acked_count(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
tp->westwood.cumul_ack = westwood_acked(sk);
/* If cumul_ack is 0 this is a dupack since it's not moving
* tp->snd_una.
*/
if (!(tp->westwood.cumul_ack))
westwood_dupack_update(sk);
if (westwood_may_change_cumul(tp)) {
/* Partial or delayed ack */
if (tp->westwood.accounted >= tp->westwood.cumul_ack)
westwood_partial_update(tp);
else
westwood_complete_update(tp);
}
tp->westwood.snd_una = tp->snd_una;
return tp->westwood.cumul_ack;
}
/*
* @__tcp_westwood_slow_bw
* It is called when something is going wrong..even if there could
* be no problems! Infact a simple delayed packet may trigger a
* dupack. But we need to be careful in such case.
*/
static void __tcp_westwood_slow_bw(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
westwood_update_window(sk, tcp_time_stamp);
tp->westwood.bk += westwood_acked_count(sk);
tp->westwood.rtt_min = westwood_update_rttmin(sk);
}
static inline void tcp_westwood_slow_bw(struct sock *sk, struct sk_buff *skb)
{
if (tcp_is_westwood(tcp_sk(sk)))
__tcp_westwood_slow_bw(sk, skb);
}
/* This routine deals with incoming acks, but not outgoing ones. */
static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
{
@ -2884,6 +2255,7 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
u32 ack = TCP_SKB_CB(skb)->ack_seq;
u32 prior_in_flight;
s32 seq_rtt;
s32 seq_usrtt = 0;
int prior_packets;
/* If the ack is newer than sent or older than previous acks
@ -2902,9 +2274,10 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
*/
tcp_update_wl(tp, ack, ack_seq);
tp->snd_una = ack;
tcp_westwood_fast_bw(sk, skb);
flag |= FLAG_WIN_UPDATE;
tcp_ca_event(tp, CA_EVENT_FAST_ACK);
NET_INC_STATS_BH(LINUX_MIB_TCPHPACKS);
} else {
if (ack_seq != TCP_SKB_CB(skb)->end_seq)
@ -2920,7 +2293,7 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
if (TCP_ECN_rcv_ecn_echo(tp, skb->h.th))
flag |= FLAG_ECE;
tcp_westwood_slow_bw(sk,skb);
tcp_ca_event(tp, CA_EVENT_SLOW_ACK);
}
/* We passed data and got it acked, remove any soft error
@ -2935,22 +2308,20 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
prior_in_flight = tcp_packets_in_flight(tp);
/* See if we can take anything off of the retransmit queue. */
flag |= tcp_clean_rtx_queue(sk, &seq_rtt);
flag |= tcp_clean_rtx_queue(sk, &seq_rtt,
tp->ca_ops->rtt_sample ? &seq_usrtt : NULL);
if (tp->frto_counter)
tcp_process_frto(sk, prior_snd_una);
if (tcp_ack_is_dubious(tp, flag)) {
/* Advanve CWND, if state allows this. */
if ((flag & FLAG_DATA_ACKED) &&
(tcp_vegas_enabled(tp) || prior_in_flight >= tp->snd_cwnd) &&
tcp_may_raise_cwnd(tp, flag))
tcp_cong_avoid(tp, ack, seq_rtt);
if ((flag & FLAG_DATA_ACKED) && tcp_may_raise_cwnd(tp, flag))
tcp_cong_avoid(tp, ack, seq_rtt, prior_in_flight, 0);
tcp_fastretrans_alert(sk, prior_snd_una, prior_packets, flag);
} else {
if ((flag & FLAG_DATA_ACKED) &&
(tcp_vegas_enabled(tp) || prior_in_flight >= tp->snd_cwnd))
tcp_cong_avoid(tp, ack, seq_rtt);
if ((flag & FLAG_DATA_ACKED))
tcp_cong_avoid(tp, ack, seq_rtt, prior_in_flight, 1);
}
if ((flag & FLAG_FORWARD_PROGRESS) || !(flag&FLAG_NOT_DUP))
@ -4552,6 +3923,8 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
tcp_init_metrics(sk);
tcp_init_congestion_control(tp);
/* Prevent spurious tcp_cwnd_restart() on first data
* packet.
*/
@ -4708,9 +4081,6 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
if(tp->af_specific->conn_request(sk, skb) < 0)
return 1;
init_westwood(sk);
init_bictcp(tp);
/* Now we have several options: In theory there is
* nothing else in the frame. KA9Q has an option to
* send data with the syn, BSD accepts data with the
@ -4732,9 +4102,6 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
goto discard;
case TCP_SYN_SENT:
init_westwood(sk);
init_bictcp(tp);
queued = tcp_rcv_synsent_state_process(sk, skb, th, len);
if (queued >= 0)
return queued;
@ -4816,7 +4183,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
*/
if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
!tp->srtt)
tcp_ack_saw_tstamp(tp, 0);
tcp_ack_saw_tstamp(tp, 0, 0);
if (tp->rx_opt.tstamp_ok)
tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;
@ -4828,6 +4195,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
tcp_init_metrics(sk);
tcp_init_congestion_control(tp);
/* Prevent spurious tcp_cwnd_restart() on
* first data packet.
*/

3
net/ipv4/tcp_ipv4.c
View File

@ -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);

4
net/ipv4/tcp_minisocks.c
View File

@ -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;

23
net/ipv4/tcp_output.c
View File

@ -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;

2
net/ipv6/tcp_ipv6.c
View File

@ -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);