Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6

[deliverable/linux.git] / net / ipv4 / tcp_cubic.c

diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c
index 71d5f2f29fa62b92cb4ae4d4762b5322d017f5d3..34340c9c95fab4f3c9aa108fbed4dd7f69028cd9 100644 (file)
--- a/net/ipv4/tcp_cubic.c
+++ b/net/ipv4/tcp_cubic.c
@@ -39,7 +39,7 @@
 
 /* Number of delay samples for detecting the increase of delay */
 #define HYSTART_MIN_SAMPLES    8
-#define HYSTART_DELAY_MIN      (2U<<3)
+#define HYSTART_DELAY_MIN      (4U<<3)
 #define HYSTART_DELAY_MAX      (16U<<3)
 #define HYSTART_DELAY_THRESH(x)        clamp(x, HYSTART_DELAY_MIN, HYSTART_DELAY_MAX)
 
@@ -52,6 +52,7 @@ static int tcp_friendliness __read_mostly = 1;
 static int hystart __read_mostly = 1;
 static int hystart_detect __read_mostly = HYSTART_ACK_TRAIN | HYSTART_DELAY;
 static int hystart_low_window __read_mostly = 16;
+static int hystart_ack_delta __read_mostly = 2;
 
 static u32 cube_rtt_scale __read_mostly;
 static u32 beta_scale __read_mostly;
@@ -75,6 +76,8 @@ MODULE_PARM_DESC(hystart_detect, "hyrbrid slow start detection mechanisms"
                 " 1: packet-train 2: delay 3: both packet-train and delay");
 module_param(hystart_low_window, int, 0644);
 MODULE_PARM_DESC(hystart_low_window, "lower bound cwnd for hybrid slow start");
+module_param(hystart_ack_delta, int, 0644);
+MODULE_PARM_DESC(hystart_ack_delta, "spacing between ack's indicating train (msecs)");
 
 /* BIC TCP Parameters */
 struct bictcp {
@@ -85,7 +88,7 @@ struct bictcp {
        u32     last_time;      /* time when updated last_cwnd */
        u32     bic_origin_point;/* origin point of bic function */
        u32     bic_K;          /* time to origin point from the beginning of the current epoch */
-       u32     delay_min;      /* min delay */
+       u32     delay_min;      /* min delay (msec << 3) */
        u32     epoch_start;    /* beginning of an epoch */
        u32     ack_cnt;        /* number of acks */
        u32     tcp_cwnd;       /* estimated tcp cwnd */
@@ -95,7 +98,7 @@ struct bictcp {
        u8      found;          /* the exit point is found? */
        u32     round_start;    /* beginning of each round */
        u32     end_seq;        /* end_seq of the round */
-       u32     last_jiffies;   /* last time when the ACK spacing is close */
+       u32     last_ack;       /* last time when the ACK spacing is close */
        u32     curr_rtt;       /* the minimum rtt of current round */
 };
 
@@ -116,12 +119,21 @@ static inline void bictcp_reset(struct bictcp *ca)
        ca->found = 0;
 }
 
+static inline u32 bictcp_clock(void)
+{
+#if HZ < 1000
+       return ktime_to_ms(ktime_get_real());
+#else
+       return jiffies_to_msecs(jiffies);
+#endif
+}
+
 static inline void bictcp_hystart_reset(struct sock *sk)
 {
        struct tcp_sock *tp = tcp_sk(sk);
        struct bictcp *ca = inet_csk_ca(sk);
 
-       ca->round_start = ca->last_jiffies = jiffies;
+       ca->round_start = ca->last_ack = bictcp_clock();
        ca->end_seq = tp->snd_nxt;
        ca->curr_rtt = 0;
        ca->sample_cnt = 0;
@@ -236,8 +248,8 @@ static inline void bictcp_update(struct bictcp *ca, u32 cwnd)
         */
 
        /* change the unit from HZ to bictcp_HZ */
-       t = ((tcp_time_stamp + (ca->delay_min>>3) - ca->epoch_start)
-            << BICTCP_HZ) / HZ;
+       t = ((tcp_time_stamp + msecs_to_jiffies(ca->delay_min>>3)
+             - ca->epoch_start) << BICTCP_HZ) / HZ;
 
        if (t < ca->bic_K)              /* t - K */
                offs = ca->bic_K - t;
@@ -258,6 +270,13 @@ static inline void bictcp_update(struct bictcp *ca, u32 cwnd)
                ca->cnt = 100 * cwnd;              /* very small increment*/
        }
 
+       /*
+        * The initial growth of cubic function may be too conservative
+        * when the available bandwidth is still unknown.
+        */
+       if (ca->loss_cwnd == 0 && ca->cnt > 20)
+               ca->cnt = 20;   /* increase cwnd 5% per RTT */
+
        /* TCP Friendly */
        if (tcp_friendliness) {
                u32 scale = beta_scale;
@@ -339,12 +358,12 @@ static void hystart_update(struct sock *sk, u32 delay)
        struct bictcp *ca = inet_csk_ca(sk);
 
        if (!(ca->found & hystart_detect)) {
-               u32 curr_jiffies = jiffies;
+               u32 now = bictcp_clock();
 
                /* first detection parameter - ack-train detection */
-               if (curr_jiffies - ca->last_jiffies <= msecs_to_jiffies(2)) {
-                       ca->last_jiffies = curr_jiffies;
-                       if (curr_jiffies - ca->round_start >= ca->delay_min>>4)
+               if ((s32)(now - ca->last_ack) <= hystart_ack_delta) {
+                       ca->last_ack = now;
+                       if ((s32)(now - ca->round_start) > ca->delay_min >> 4)
                                ca->found |= HYSTART_ACK_TRAIN;
                }
 
@@ -391,7 +410,7 @@ static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt_us)
        if ((s32)(tcp_time_stamp - ca->epoch_start) < HZ)
                return;
 
-       delay = usecs_to_jiffies(rtt_us) << 3;
+       delay = (rtt_us << 3) / USEC_PER_MSEC;
        if (delay == 0)
                delay = 1;
 
@@ -405,7 +424,7 @@ static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt_us)
                hystart_update(sk, delay);
 }
 
-static struct tcp_congestion_ops cubictcp = {
+static struct tcp_congestion_ops cubictcp __read_mostly = {
        .init           = bictcp_init,
        .ssthresh       = bictcp_recalc_ssthresh,
        .cong_avoid     = bictcp_cong_avoid,
@@ -447,6 +466,10 @@ static int __init cubictcp_register(void)
        /* divide by bic_scale and by constant Srtt (100ms) */
        do_div(cube_factor, bic_scale * 10);
 
+       /* hystart needs ms clock resolution */
+       if (hystart && HZ < 1000)
+               cubictcp.flags |= TCP_CONG_RTT_STAMP;
+
        return tcp_register_congestion_control(&cubictcp);
 }