#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
*/
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;
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
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.
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;
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 */
* 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>
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. */
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)
{
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
* 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.
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
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
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)
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;
}
/* 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);
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);
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)
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);
}
/* 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;
* 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
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)
-{
- /* 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)
+static inline void tcp_cong_avoid(struct tcp_sock *tp, u32 ack, u32 rtt,
+ u32 in_flight, int good)
{
- 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.
*/
/* 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) {
*/
if (!(scb->flags & TCPCB_FLAG_SYN)) {
acked |= FLAG_DATA_ACKED;
+ ++pkts_acked;
} else {
acked |= FLAG_SYN_ACKED;
tp->retrans_stamp = 0;
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)
}
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
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)
{
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
*/
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)
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
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))
tcp_init_metrics(sk);
+ tcp_init_congestion_control(tp);
+
/* Prevent spurious tcp_cwnd_restart() on first data
* packet.
*/
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
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;
*/
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;
tcp_init_metrics(sk);
+ tcp_init_congestion_control(tp);
+
/* Prevent spurious tcp_cwnd_restart() on
* first data packet.
*/
projects / linux-2.6 / commitdiff