3 files changed, 298 insertions, 0 deletions

diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index dc61e6641624..e62aee0ec4c5 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -588,6 +588,19 @@ config TCP_CONG_YEAH
         For further details look here:
           http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
 
+config TCP_CONG_ILLINOIS
+        tristate "TCP Illinois"
+        depends on EXPERIMENTAL
+        default n
+        ---help---
+        TCP-Illinois is a sender-side modificatio of TCP Reno for
+        high speed long delay links. It uses round-trip-time to
+        adjust the alpha and beta parameters to achieve a higher average
+        throughput and maintain fairness.
+
+        For further details see:
+          http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
+
 choice
         prompt "Default TCP congestion control"
         default DEFAULT_CUBIC
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index eeb94d5cac96..4ff6c151d7f3 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_TCP_CONG_VENO) += tcp_veno.o
 obj-$(CONFIG_TCP_CONG_SCALABLE) += tcp_scalable.o
 obj-$(CONFIG_TCP_CONG_LP) += tcp_lp.o
 obj-$(CONFIG_TCP_CONG_YEAH) += tcp_yeah.o
+obj-$(CONFIG_TCP_CONG_ILLINOIS) += tcp_illinois.o
 obj-$(CONFIG_NETLABEL) += cipso_ipv4.o
 
 obj-$(CONFIG_XFRM) += xfrm4_policy.o xfrm4_state.o xfrm4_input.o \
diff --git a/net/ipv4/tcp_illinois.c b/net/ipv4/tcp_illinois.c
new file mode 100644
index 000000000000..91a2a34604cd
--- /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 <shemminger@linux-foundation.org>
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/inet_diag.h>
+#include <asm/div64.h>
+#include <net/tcp.h>
+
+#define ALPHA_SHIFT     7
+#define ALPHA_SCALE     (1u<<ALPHA_SHIFT)
+#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 BETA_SHIFT      6
+#define BETA_SCALE      (1u<<BETA_SHIFT)
+#define BETA_MIN        (BETA_SCALE/8)          /* 0.8 */
+#define BETA_MAX        (BETA_SCALE/2)
+#define BETA_BASE       BETA_MAX                /* 0.5 */
+
+#define THETA           5
+
+static int win_thresh __read_mostly = 15;
+module_param(win_thresh, int, 0644);
+MODULE_PARM_DESC(win_thresh, "Window threshold for starting adaptive sizing");
+
+#define MAX_RTT         0x7fffffff
+
+/* TCP Illinois Parameters */
+struct tcp_illinois {
+        u32     last_alpha;
+        u32     min_rtt;
+        u32     max_rtt;
+        u32     rtt_low;
+        u32     rtt_cnt;
+        u64     sum_rtt;
+};
+
+static void tcp_illinois_init(struct sock *sk)
+{
+        struct tcp_illinois *ca = inet_csk_ca(sk);
+
+        ca->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");