/*
* Binary Increase Congestion control for TCP
- *
+ * Home page:
+ * http://netsrv.csc.ncsu.edu/twiki/bin/view/Main/BIC
* This is from the implementation of BICTCP in
* Lison-Xu, Kahaled Harfoush, and Injong Rhee.
* "Binary Increase Congestion Control for Fast, Long Distance
* Networks" in InfoComm 2004
* Available from:
- * http://www.csc.ncsu.edu/faculty/rhee/export/bitcp.pdf
+ * http://netsrv.csc.ncsu.edu/export/bitcp.pdf
*
* Unless BIC is enabled and congestion window is large
* this behaves the same as the original Reno.
*/
-#include <linux/config.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <net/tcp.h>
static int max_increment = 16;
static int low_window = 14;
static int beta = 819; /* = 819/1024 (BICTCP_BETA_SCALE) */
-static int low_utilization_threshold = 153;
-static int low_utilization_period = 2;
-static int initial_ssthresh = 100;
+static int initial_ssthresh;
static int smooth_part = 20;
module_param(fast_convergence, int, 0644);
MODULE_PARM_DESC(low_window, "lower bound on congestion window (for TCP friendliness)");
module_param(beta, int, 0644);
MODULE_PARM_DESC(beta, "beta for multiplicative increase");
-module_param(low_utilization_threshold, int, 0644);
-MODULE_PARM_DESC(low_utilization_threshold, "percent (scaled by 1024) for low utilization mode");
-module_param(low_utilization_period, int, 0644);
-MODULE_PARM_DESC(low_utilization_period, "if average delay exceeds then goto to low utilization mode (seconds)");
module_param(initial_ssthresh, int, 0644);
MODULE_PARM_DESC(initial_ssthresh, "initial value of slow start threshold");
module_param(smooth_part, int, 0644);
u32 loss_cwnd; /* congestion window at last loss */
u32 last_cwnd; /* the last snd_cwnd */
u32 last_time; /* time when updated last_cwnd */
- u32 delay_min; /* min delay */
- u32 delay_max; /* max delay */
- u32 last_delay;
- u8 low_utilization;/* 0: high; 1: low */
- u32 low_utilization_start; /* starting time of low utilization detection*/
u32 epoch_start; /* beginning of an epoch */
#define ACK_RATIO_SHIFT 4
u32 delayed_ack; /* estimate the ratio of Packets/ACKs << 4 */
ca->loss_cwnd = 0;
ca->last_cwnd = 0;
ca->last_time = 0;
- ca->delay_min = 0;
- ca->delay_max = 0;
- ca->last_delay = 0;
- ca->low_utilization = 0;
- ca->low_utilization_start = 0;
ca->epoch_start = 0;
ca->delayed_ack = 2 << ACK_RATIO_SHIFT;
}
}
/* if in slow start or link utilization is very low */
- if ( ca->loss_cwnd == 0 ||
- (cwnd > ca->loss_cwnd && ca->low_utilization)) {
+ if (ca->loss_cwnd == 0) {
if (ca->cnt > 20) /* increase cwnd 5% per RTT */
ca->cnt = 20;
}
ca->cnt = 1;
}
-
-/* Detect low utilization in congestion avoidance */
-static inline void bictcp_low_utilization(struct sock *sk, int flag)
-{
- const struct tcp_sock *tp = tcp_sk(sk);
- struct bictcp *ca = inet_csk_ca(sk);
- u32 dist, delay;
-
- /* No time stamp */
- if (!(tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr) ||
- /* Discard delay samples right after fast recovery */
- tcp_time_stamp < ca->epoch_start + HZ ||
- /* this delay samples may not be accurate */
- flag == 0) {
- ca->last_delay = 0;
- goto notlow;
- }
-
- delay = ca->last_delay<<3; /* use the same scale as tp->srtt*/
- ca->last_delay = tcp_time_stamp - tp->rx_opt.rcv_tsecr;
- if (delay == 0) /* no previous delay sample */
- goto notlow;
-
- /* first time call or link delay decreases */
- if (ca->delay_min == 0 || ca->delay_min > delay) {
- ca->delay_min = ca->delay_max = delay;
- goto notlow;
- }
-
- if (ca->delay_max < delay)
- ca->delay_max = delay;
-
- /* utilization is low, if avg delay < dist*threshold
- for checking_period time */
- dist = ca->delay_max - ca->delay_min;
- if (dist <= ca->delay_min>>6 ||
- tp->srtt - ca->delay_min >= (dist*low_utilization_threshold)>>10)
- goto notlow;
-
- if (ca->low_utilization_start == 0) {
- ca->low_utilization = 0;
- ca->low_utilization_start = tcp_time_stamp;
- } else if ((s32)(tcp_time_stamp - ca->low_utilization_start)
- > low_utilization_period*HZ) {
- ca->low_utilization = 1;
- }
-
- return;
-
- notlow:
- ca->low_utilization = 0;
- ca->low_utilization_start = 0;
-
-}
-
-static void bictcp_cong_avoid(struct sock *sk, u32 ack,
- u32 seq_rtt, u32 in_flight, int data_acked)
+static void bictcp_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
{
struct tcp_sock *tp = tcp_sk(sk);
struct bictcp *ca = inet_csk_ca(sk);
- bictcp_low_utilization(sk, data_acked);
-
if (!tcp_is_cwnd_limited(sk, in_flight))
return;
- if (tp->snd_cwnd <= tp->snd_ssthresh) {
- /* In "safe" area, increase. */
- if (tp->snd_cwnd < tp->snd_cwnd_clamp)
- tp->snd_cwnd++;
- } else {
+ if (tp->snd_cwnd <= tp->snd_ssthresh)
+ tcp_slow_start(tp);
+ else {
bictcp_update(ca, tp->snd_cwnd);
-
- /* In dangerous area, increase slowly.
- * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd
- */
- if (tp->snd_cwnd_cnt >= ca->cnt) {
- if (tp->snd_cwnd < tp->snd_cwnd_clamp)
- tp->snd_cwnd++;
- tp->snd_cwnd_cnt = 0;
- } else
- tp->snd_cwnd_cnt++;
+ tcp_cong_avoid_ai(tp, ca->cnt);
}
}
ca->epoch_start = 0; /* end of epoch */
- /* in case of wrong delay_max*/
- if (ca->delay_min > 0 && ca->delay_max > ca->delay_min)
- ca->delay_max = ca->delay_min
- + ((ca->delay_max - ca->delay_min)* 90) / 100;
-
/* Wmax and fast convergence */
if (tp->snd_cwnd < ca->last_max_cwnd && fast_convergence)
ca->last_max_cwnd = (tp->snd_cwnd * (BICTCP_BETA_SCALE + beta))
return max(tp->snd_cwnd, ca->last_max_cwnd);
}
-static u32 bictcp_min_cwnd(struct sock *sk)
-{
- const struct tcp_sock *tp = tcp_sk(sk);
- return tp->snd_ssthresh;
-}
-
static void bictcp_state(struct sock *sk, u8 new_state)
{
if (new_state == TCP_CA_Loss)
bictcp_reset(inet_csk_ca(sk));
}
-/* Track delayed acknowledgement ratio using sliding window
+/* Track delayed acknowledgment ratio using sliding window
* ratio = (15*ratio + sample) / 16
*/
-static void bictcp_acked(struct sock *sk, u32 cnt)
+static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
- if (cnt > 0 && icsk->icsk_ca_state == TCP_CA_Open) {
+ if (icsk->icsk_ca_state == TCP_CA_Open) {
struct bictcp *ca = inet_csk_ca(sk);
cnt -= ca->delayed_ack >> ACK_RATIO_SHIFT;
ca->delayed_ack += cnt;
.cong_avoid = bictcp_cong_avoid,
.set_state = bictcp_state,
.undo_cwnd = bictcp_undo_cwnd,
- .min_cwnd = bictcp_min_cwnd,
.pkts_acked = bictcp_acked,
.owner = THIS_MODULE,
.name = "bic",
static int __init bictcp_register(void)
{
- BUG_ON(sizeof(struct bictcp) > ICSK_CA_PRIV_SIZE);
+ BUILD_BUG_ON(sizeof(struct bictcp) > ICSK_CA_PRIV_SIZE);
return tcp_register_congestion_control(&bictcp);
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff