From c462238d6a6d8ee855bda10f9fff442971540ed2 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Fri, 20 Apr 2007 17:07:51 -0700 Subject: [TCP]: TCP Illinois congestion control (rev3) This is an implementation of TCP Illinois invented by Shao Liu at University of Illinois. It is a another variant of Reno which adapts the alpha and beta parameters based on RTT. The basic idea is to increase window less rapidly as delay approaches the maximum. See the papers and talks to get a more complete description. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/ipv4/tcp_illinois.c | 284 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 284 insertions(+) create mode 100644 net/ipv4/tcp_illinois.c (limited to 'net/ipv4/tcp_illinois.c') diff --git a/net/ipv4/tcp_illinois.c b/net/ipv4/tcp_illinois.c new file mode 100644 index 00000000000..91a2a34604c --- /dev/null +++ b/net/ipv4/tcp_illinois.c @@ -0,0 +1,284 @@ +/* + * TCP Illinois congestion control. + * Home page: + * http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html + * + * The algorithm is described in: + * "TCP-Illinois: A Loss and Delay-Based Congestion Control Algorithm + * for High-Speed Networks" + * http://www.ews.uiuc.edu/~shaoliu/papersandslides/liubassri06perf.pdf + * + * Implemented from description in paper and ns-2 simulation. + * Copyright (C) 2007 Stephen Hemminger + */ + +#include +#include +#include +#include +#include + +#define ALPHA_SHIFT 7 +#define ALPHA_SCALE (1u<last_alpha = ALPHA_BASE; + ca->min_rtt = 0x7fffffff; +} + +/* + * Keep track of min, max and average RTT + */ +static void tcp_illinois_rtt_calc(struct sock *sk, u32 rtt) +{ + struct tcp_illinois *ca = inet_csk_ca(sk); + + if (rtt < ca->min_rtt) + ca->min_rtt = rtt; + if (rtt > ca->max_rtt) + ca->max_rtt = rtt; + + if (++ca->rtt_cnt == 1) + ca->sum_rtt = rtt; + else + ca->sum_rtt += rtt; +} + +/* max queuing delay */ +static inline u32 max_delay(const struct tcp_illinois *ca) +{ + return ca->max_rtt - ca->min_rtt; +} + +/* average queueing delay */ +static u32 avg_delay(struct tcp_illinois *ca) +{ + u64 avg_rtt = ca->sum_rtt; + + do_div(avg_rtt, ca->rtt_cnt); + + ca->sum_rtt = 0; + ca->rtt_cnt = 0; + + return avg_rtt - ca->min_rtt; +} + +/* + * Compute value of alpha used for additive increase. + * If small window then use 1.0, equivalent to Reno. + * + * For larger windows, adjust based on average delay. + * A. If average delay is at minimum (we are uncongested), + * then use large alpha (10.0) to increase faster. + * B. If average delay is at maximum (getting congested) + * then use small alpha (1.0) + * + * The result is a convex window growth curve. + */ +static u32 alpha(const struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct tcp_illinois *ca = inet_csk_ca(sk); + u32 dm = max_delay(ca); + u32 da = avg_delay(ca); + u32 d1, a; + + if (tp->snd_cwnd < win_thresh) + return ALPHA_BASE; /* same as Reno (1.0) */ + + d1 = dm / 100; + if (da <= d1) { + /* Don't let noise force agressive response */ + if (ca->rtt_low < THETA) { + ++ca->rtt_low; + return ca->last_alpha; + } else + return ALPHA_MAX; + } + + ca->rtt_low = 0; + + /* + * Based on: + * + * (dm - d1) amin amax + * k1 = ------------------- + * amax - amin + * + * (dm - d1) amin + * k2 = ---------------- - d1 + * amax - amin + * + * k1 + * alpha = ---------- + * k2 + da + */ + + dm -= d1; + da -= d1; + + a = (dm * ALPHA_MAX) / (dm - (da * (ALPHA_MAX - ALPHA_MIN)) / ALPHA_MIN); + ca->last_alpha = a; + return a; +} + +/* + * Increase window in response to successful acknowledgment. + */ +static void tcp_illinois_cong_avoid(struct sock *sk, u32 ack, u32 rtt, + u32 in_flight, int flag) +{ + struct tcp_sock *tp = tcp_sk(sk); + + /* RFC2861 only increase cwnd if fully utilized */ + if (!tcp_is_cwnd_limited(sk, in_flight)) + return; + + /* In slow start */ + if (tp->snd_cwnd <= tp->snd_ssthresh) + tcp_slow_start(tp); + + else { + /* additive increase cwnd += alpha / cwnd */ + if ((tp->snd_cwnd_cnt * alpha(sk)) >> ALPHA_SHIFT >= tp->snd_cwnd) { + if (tp->snd_cwnd < tp->snd_cwnd_clamp) + tp->snd_cwnd++; + tp->snd_cwnd_cnt = 0; + } else + tp->snd_cwnd_cnt++; + } +} + +/* + * Beta used for multiplicative decrease. + * For small window sizes returns same value as Reno (0.5) + * + * If delay is small (10% of max) then beta = 1/8 + * If delay is up to 80% of max then beta = 1/2 + * In between is a linear function + */ +static inline u32 beta(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct tcp_illinois *ca = inet_csk_ca(sk); + u32 dm = max_delay(ca); + u32 da = avg_delay(ca); + u32 d2, d3; + + if (tp->snd_cwnd < win_thresh) + return BETA_BASE; + + d2 = dm / 10; + if (da <= d2) + return BETA_MIN; + d3 = (8 * dm) / 10; + if (da >= d3 || d3 <= d2) + return BETA_MAX; + + /* + * Based on: + * + * bmin d3 - bmax d2 + * k3 = ------------------- + * d3 - d2 + * + * bmax - bmin + * k4 = ------------- + * d3 - d2 + * + * b = k3 + k4 da + */ + return (BETA_MIN * d3 - BETA_MAX * d2 + (BETA_MAX - BETA_MIN) * da) + / (d3 - d2); +} + +static u32 tcp_illinois_ssthresh(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + + /* Multiplicative decrease */ + return max((tp->snd_cwnd * beta(sk)) >> BETA_SHIFT, 2U); +} + +/* Extract info for TCP socket info provided via netlink. + * We aren't really doing Vegas, but we can provide RTT info + */ +static void tcp_illinois_get_info(struct sock *sk, u32 ext, + struct sk_buff *skb) +{ + const struct tcp_illinois *ca = inet_csk_ca(sk); + + if (ext & (1 << (INET_DIAG_VEGASINFO - 1))) { + struct tcpvegas_info info = { + .tcpv_enabled = 1, + .tcpv_rttcnt = ca->rtt_cnt, + .tcpv_minrtt = ca->min_rtt, + }; + u64 avg_rtt = ca->sum_rtt; + do_div(avg_rtt, ca->rtt_cnt); + info.tcpv_rtt = avg_rtt; + + nla_put(skb, INET_DIAG_VEGASINFO, sizeof(info), &info); + } +} + +static struct tcp_congestion_ops tcp_illinois = { + .init = tcp_illinois_init, + .ssthresh = tcp_illinois_ssthresh, + .min_cwnd = tcp_reno_min_cwnd, + .cong_avoid = tcp_illinois_cong_avoid, + .rtt_sample = tcp_illinois_rtt_calc, + .get_info = tcp_illinois_get_info, + + .owner = THIS_MODULE, + .name = "illinois", +}; + +static int __init tcp_illinois_register(void) +{ + BUILD_BUG_ON(sizeof(struct tcp_illinois) > ICSK_CA_PRIV_SIZE); + return tcp_register_congestion_control(&tcp_illinois); +} + +static void __exit tcp_illinois_unregister(void) +{ + tcp_unregister_congestion_control(&tcp_illinois); +} + +module_init(tcp_illinois_register); +module_exit(tcp_illinois_unregister); + +MODULE_AUTHOR("Stephen Hemminger, Shao Liu"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("TCP Illinois"); +MODULE_VERSION("0.3"); -- cgit v1.2.3 From 65d1b4a7e73fe0e1f5275ad7d2d3547981480886 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Mon, 23 Apr 2007 22:24:32 -0700 Subject: [TCP]: TCP Illinois update. This version more closely matches the paper, and fixes several math errors. The biggest difference is that it updates alpha/beta once per RTT Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/ipv4/tcp_illinois.c | 298 ++++++++++++++++++++++++++++++------------------ 1 file changed, 186 insertions(+), 112 deletions(-) (limited to 'net/ipv4/tcp_illinois.c') diff --git a/net/ipv4/tcp_illinois.c b/net/ipv4/tcp_illinois.c index 91a2a34604c..ae629860088 100644 --- a/net/ipv4/tcp_illinois.c +++ b/net/ipv4/tcp_illinois.c @@ -23,74 +23,106 @@ #define ALPHA_MIN ((3*ALPHA_SCALE)/10) /* ~0.3 */ #define ALPHA_MAX (10*ALPHA_SCALE) /* 10.0 */ #define ALPHA_BASE ALPHA_SCALE /* 1.0 */ +#define U32_MAX ((u32)~0U) +#define RTT_MAX (U32_MAX / ALPHA_MAX) /* 3.3 secs */ #define BETA_SHIFT 6 #define BETA_SCALE (1u<end_seq = tp->snd_nxt; + ca->cnt_rtt = 0; + ca->sum_rtt = 0; + + /* TODO: age max_rtt? */ +} + static void tcp_illinois_init(struct sock *sk) { - struct tcp_illinois *ca = inet_csk_ca(sk); + struct illinois *ca = inet_csk_ca(sk); + + ca->alpha = ALPHA_MAX; + ca->beta = BETA_BASE; + ca->base_rtt = 0x7fffffff; + ca->max_rtt = 0; + + ca->acked = 0; + ca->rtt_low = 0; + ca->rtt_above = 0; - ca->last_alpha = ALPHA_BASE; - ca->min_rtt = 0x7fffffff; + rtt_reset(sk); } -/* - * Keep track of min, max and average RTT - */ -static void tcp_illinois_rtt_calc(struct sock *sk, u32 rtt) +/* Measure RTT for each ack. */ +static void tcp_illinois_rtt_sample(struct sock *sk, u32 rtt) { - struct tcp_illinois *ca = inet_csk_ca(sk); + struct illinois *ca = inet_csk_ca(sk); + + /* ignore bogus values, this prevents wraparound in alpha math */ + if (rtt > RTT_MAX) + rtt = RTT_MAX; - if (rtt < ca->min_rtt) - ca->min_rtt = rtt; - if (rtt > ca->max_rtt) + /* keep track of minimum RTT seen so far */ + if (ca->base_rtt > rtt) + ca->base_rtt = rtt; + + /* and max */ + if (ca->max_rtt < rtt) ca->max_rtt = rtt; - if (++ca->rtt_cnt == 1) - ca->sum_rtt = rtt; - else - ca->sum_rtt += rtt; + ++ca->cnt_rtt; + ca->sum_rtt += rtt; } -/* max queuing delay */ -static inline u32 max_delay(const struct tcp_illinois *ca) +/* Capture count of packets covered by ack, to adjust for delayed acks */ +static void tcp_illinois_acked(struct sock *sk, u32 pkts_acked) { - return ca->max_rtt - ca->min_rtt; + struct illinois *ca = inet_csk_ca(sk); + ca->acked = pkts_acked; } -/* average queueing delay */ -static u32 avg_delay(struct tcp_illinois *ca) +/* Maximum queuing delay */ +static inline u32 max_delay(const struct illinois *ca) { - u64 avg_rtt = ca->sum_rtt; - - do_div(avg_rtt, ca->rtt_cnt); + return ca->max_rtt - ca->base_rtt; +} - ca->sum_rtt = 0; - ca->rtt_cnt = 0; +/* Average queuing delay */ +static inline u32 avg_delay(const struct illinois *ca) +{ + u64 t = ca->sum_rtt; - return avg_rtt - ca->min_rtt; + do_div(t, ca->cnt_rtt); + return t - ca->base_rtt; } /* @@ -101,32 +133,31 @@ static u32 avg_delay(struct tcp_illinois *ca) * A. If average delay is at minimum (we are uncongested), * then use large alpha (10.0) to increase faster. * B. If average delay is at maximum (getting congested) - * then use small alpha (1.0) + * then use small alpha (0.3) * * The result is a convex window growth curve. */ -static u32 alpha(const struct sock *sk) +static u32 alpha(struct illinois *ca, u32 da, u32 dm) { - struct tcp_sock *tp = tcp_sk(sk); - struct tcp_illinois *ca = inet_csk_ca(sk); - u32 dm = max_delay(ca); - u32 da = avg_delay(ca); - u32 d1, a; + u32 d1 = dm / 100; /* Low threshold */ - if (tp->snd_cwnd < win_thresh) - return ALPHA_BASE; /* same as Reno (1.0) */ - - d1 = dm / 100; if (da <= d1) { - /* Don't let noise force agressive response */ - if (ca->rtt_low < THETA) { - ++ca->rtt_low; - return ca->last_alpha; - } else + /* If never got out of low delay zone, then use max */ + if (!ca->rtt_above) return ALPHA_MAX; + + /* Wait for 5 good RTT's before allowing alpha to go alpha max. + * This prevents one good RTT from causing sudden window increase. + */ + if (++ca->rtt_low < theta) + return ca->alpha; + + ca->rtt_low = 0; + ca->rtt_above = 0; + return ALPHA_MAX; } - ca->rtt_low = 0; + ca->rtt_above = 1; /* * Based on: @@ -146,37 +177,8 @@ static u32 alpha(const struct sock *sk) dm -= d1; da -= d1; - - a = (dm * ALPHA_MAX) / (dm - (da * (ALPHA_MAX - ALPHA_MIN)) / ALPHA_MIN); - ca->last_alpha = a; - return a; -} - -/* - * Increase window in response to successful acknowledgment. - */ -static void tcp_illinois_cong_avoid(struct sock *sk, u32 ack, u32 rtt, - u32 in_flight, int flag) -{ - struct tcp_sock *tp = tcp_sk(sk); - - /* RFC2861 only increase cwnd if fully utilized */ - if (!tcp_is_cwnd_limited(sk, in_flight)) - return; - - /* In slow start */ - if (tp->snd_cwnd <= tp->snd_ssthresh) - tcp_slow_start(tp); - - else { - /* additive increase cwnd += alpha / cwnd */ - if ((tp->snd_cwnd_cnt * alpha(sk)) >> ALPHA_SHIFT >= tp->snd_cwnd) { - if (tp->snd_cwnd < tp->snd_cwnd_clamp) - tp->snd_cwnd++; - tp->snd_cwnd_cnt = 0; - } else - tp->snd_cwnd_cnt++; - } + return (dm * ALPHA_MAX) / + (dm + (da * (ALPHA_MAX - ALPHA_MIN)) / ALPHA_MIN); } /* @@ -187,20 +189,14 @@ static void tcp_illinois_cong_avoid(struct sock *sk, u32 ack, u32 rtt, * If delay is up to 80% of max then beta = 1/2 * In between is a linear function */ -static inline u32 beta(struct sock *sk) +static u32 beta(u32 da, u32 dm) { - struct tcp_sock *tp = tcp_sk(sk); - struct tcp_illinois *ca = inet_csk_ca(sk); - u32 dm = max_delay(ca); - u32 da = avg_delay(ca); u32 d2, d3; - if (tp->snd_cwnd < win_thresh) - return BETA_BASE; - d2 = dm / 10; if (da <= d2) return BETA_MIN; + d3 = (8 * dm) / 10; if (da >= d3 || d3 <= d2) return BETA_MAX; @@ -222,31 +218,107 @@ static inline u32 beta(struct sock *sk) / (d3 - d2); } +/* Update alpha and beta values once per RTT */ +static void update_params(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct illinois *ca = inet_csk_ca(sk); + + if (tp->snd_cwnd < win_thresh) { + ca->alpha = ALPHA_BASE; + ca->beta = BETA_BASE; + } else if (ca->cnt_rtt > 0) { + u32 dm = max_delay(ca); + u32 da = avg_delay(ca); + + ca->alpha = alpha(ca, da, dm); + ca->beta = beta(da, dm); + } + + rtt_reset(sk); +} + +/* + * In case of loss, reset to default values + */ +static void tcp_illinois_state(struct sock *sk, u8 new_state) +{ + struct illinois *ca = inet_csk_ca(sk); + + if (new_state == TCP_CA_Loss) { + ca->alpha = ALPHA_BASE; + ca->beta = BETA_BASE; + ca->rtt_low = 0; + ca->rtt_above = 0; + rtt_reset(sk); + } +} + +/* + * Increase window in response to successful acknowledgment. + */ +static void tcp_illinois_cong_avoid(struct sock *sk, u32 ack, u32 rtt, + u32 in_flight, int flag) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct illinois *ca = inet_csk_ca(sk); + + if (after(ack, ca->end_seq)) + update_params(sk); + + /* RFC2861 only increase cwnd if fully utilized */ + if (!tcp_is_cwnd_limited(sk, in_flight)) + return; + + /* In slow start */ + if (tp->snd_cwnd <= tp->snd_ssthresh) + tcp_slow_start(tp); + + else { + u32 delta; + + /* snd_cwnd_cnt is # of packets since last cwnd increment */ + tp->snd_cwnd_cnt += ca->acked; + ca->acked = 1; + + /* This is close approximation of: + * tp->snd_cwnd += alpha/tp->snd_cwnd + */ + delta = (tp->snd_cwnd_cnt * ca->alpha) >> ALPHA_SHIFT; + if (delta >= tp->snd_cwnd) { + tp->snd_cwnd = min(tp->snd_cwnd + delta / tp->snd_cwnd, + (u32) tp->snd_cwnd_clamp); + tp->snd_cwnd_cnt = 0; + } + } +} + static u32 tcp_illinois_ssthresh(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); + struct illinois *ca = inet_csk_ca(sk); /* Multiplicative decrease */ - return max((tp->snd_cwnd * beta(sk)) >> BETA_SHIFT, 2U); + return max((tp->snd_cwnd * ca->beta) >> BETA_SHIFT, 2U); } -/* Extract info for TCP socket info provided via netlink. - * We aren't really doing Vegas, but we can provide RTT info - */ -static void tcp_illinois_get_info(struct sock *sk, u32 ext, - struct sk_buff *skb) + +/* Extract info for Tcp socket info provided via netlink. */ +static void tcp_illinois_info(struct sock *sk, u32 ext, + struct sk_buff *skb) { - const struct tcp_illinois *ca = inet_csk_ca(sk); + const struct illinois *ca = inet_csk_ca(sk); if (ext & (1 << (INET_DIAG_VEGASINFO - 1))) { struct tcpvegas_info info = { .tcpv_enabled = 1, - .tcpv_rttcnt = ca->rtt_cnt, - .tcpv_minrtt = ca->min_rtt, + .tcpv_rttcnt = ca->cnt_rtt, + .tcpv_minrtt = ca->base_rtt, }; - u64 avg_rtt = ca->sum_rtt; - do_div(avg_rtt, ca->rtt_cnt); - info.tcpv_rtt = avg_rtt; + u64 t = ca->sum_rtt; + + do_div(t, ca->cnt_rtt); + info.tcpv_rtt = t; nla_put(skb, INET_DIAG_VEGASINFO, sizeof(info), &info); } @@ -257,8 +329,10 @@ static struct tcp_congestion_ops tcp_illinois = { .ssthresh = tcp_illinois_ssthresh, .min_cwnd = tcp_reno_min_cwnd, .cong_avoid = tcp_illinois_cong_avoid, - .rtt_sample = tcp_illinois_rtt_calc, - .get_info = tcp_illinois_get_info, + .set_state = tcp_illinois_state, + .rtt_sample = tcp_illinois_rtt_sample, + .get_info = tcp_illinois_info, + .pkts_acked = tcp_illinois_acked, .owner = THIS_MODULE, .name = "illinois", @@ -266,7 +340,7 @@ static struct tcp_congestion_ops tcp_illinois = { static int __init tcp_illinois_register(void) { - BUILD_BUG_ON(sizeof(struct tcp_illinois) > ICSK_CA_PRIV_SIZE); + BUILD_BUG_ON(sizeof(struct illinois) > ICSK_CA_PRIV_SIZE); return tcp_register_congestion_control(&tcp_illinois); } @@ -281,4 +355,4 @@ module_exit(tcp_illinois_unregister); MODULE_AUTHOR("Stephen Hemminger, Shao Liu"); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("TCP Illinois"); -MODULE_VERSION("0.3"); +MODULE_VERSION("1.0"); -- cgit v1.2.3 From 164891aadf1721fca4dce473bb0e0998181537c6 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Mon, 23 Apr 2007 22:26:16 -0700 Subject: [TCP]: Congestion control API update. Do some simple changes to make congestion control API faster/cleaner. * use ktime_t rather than timeval * merge rtt sampling into existing ack callback this means one indirect call versus two per ack. * use flags bits to store options/settings Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/ipv4/tcp_illinois.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) (limited to 'net/ipv4/tcp_illinois.c') diff --git a/net/ipv4/tcp_illinois.c b/net/ipv4/tcp_illinois.c index ae629860088..8e3165917f7 100644 --- a/net/ipv4/tcp_illinois.c +++ b/net/ipv4/tcp_illinois.c @@ -83,9 +83,14 @@ static void tcp_illinois_init(struct sock *sk) } /* Measure RTT for each ack. */ -static void tcp_illinois_rtt_sample(struct sock *sk, u32 rtt) +static void tcp_illinois_acked(struct sock *sk, u32 pkts_acked, ktime_t last) { struct illinois *ca = inet_csk_ca(sk); + u32 rtt; + + ca->acked = pkts_acked; + + rtt = ktime_to_ns(net_timedelta(last)) / NSEC_PER_USEC; /* ignore bogus values, this prevents wraparound in alpha math */ if (rtt > RTT_MAX) @@ -103,13 +108,6 @@ static void tcp_illinois_rtt_sample(struct sock *sk, u32 rtt) ca->sum_rtt += rtt; } -/* Capture count of packets covered by ack, to adjust for delayed acks */ -static void tcp_illinois_acked(struct sock *sk, u32 pkts_acked) -{ - struct illinois *ca = inet_csk_ca(sk); - ca->acked = pkts_acked; -} - /* Maximum queuing delay */ static inline u32 max_delay(const struct illinois *ca) { @@ -325,12 +323,12 @@ static void tcp_illinois_info(struct sock *sk, u32 ext, } static struct tcp_congestion_ops tcp_illinois = { + .flags = TCP_CONG_RTT_STAMP, .init = tcp_illinois_init, .ssthresh = tcp_illinois_ssthresh, .min_cwnd = tcp_reno_min_cwnd, .cong_avoid = tcp_illinois_cong_avoid, .set_state = tcp_illinois_state, - .rtt_sample = tcp_illinois_rtt_sample, .get_info = tcp_illinois_info, .pkts_acked = tcp_illinois_acked, -- cgit v1.2.3 From 84299b3bc4eaedc0734fcc9052b01291e44445fc Mon Sep 17 00:00:00 2001 From: YOSHIFUJI Hideaki Date: Tue, 24 Apr 2007 16:21:38 -0700 Subject: [TCP]: Fix linkage errors on i386. To avoid raw division, use ktime_to_timeval() to get usec. Signed-off-by: YOSHIFUJI Hideaki Signed-off-by: David S. Miller --- net/ipv4/tcp_illinois.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/ipv4/tcp_illinois.c') diff --git a/net/ipv4/tcp_illinois.c b/net/ipv4/tcp_illinois.c index 8e3165917f7..4adc47c5535 100644 --- a/net/ipv4/tcp_illinois.c +++ b/net/ipv4/tcp_illinois.c @@ -90,7 +90,7 @@ static void tcp_illinois_acked(struct sock *sk, u32 pkts_acked, ktime_t last) ca->acked = pkts_acked; - rtt = ktime_to_ns(net_timedelta(last)) / NSEC_PER_USEC; + rtt = ktime_to_us(net_timedelta(last)); /* ignore bogus values, this prevents wraparound in alpha math */ if (rtt > RTT_MAX) -- cgit v1.2.3