/*
- * TCP CUBIC: Binary Increase Congestion control for TCP v2.1
- *
+ * TCP CUBIC: Binary Increase Congestion control for TCP v2.2
+ * Home page:
+ * http://netsrv.csc.ncsu.edu/twiki/bin/view/Main/BIC
* This is from the implementation of CUBIC TCP in
* Injong Rhee, Lisong Xu.
* "CUBIC: A New TCP-Friendly High-Speed TCP Variant
* in PFLDnet 2005
* Available from:
- * http://www.csc.ncsu.edu/faculty/rhee/export/bitcp/cubic-paper.pdf
+ * http://netsrv.csc.ncsu.edu/export/cubic-paper.pdf
*
* Unless CUBIC is enabled and congestion window is large
* this behaves the same as the original Reno.
#define BICTCP_BETA_SCALE 1024 /* Scale factor beta calculation
* max_cwnd = snd_cwnd * beta
*/
-#define BICTCP_B 4 /*
- * In binary search,
- * go to point (max+min)/N
- */
#define BICTCP_HZ 10 /* BIC HZ 2^10 = 1024 */
static int fast_convergence __read_mostly = 1;
-static int max_increment __read_mostly = 16;
-static int beta __read_mostly = 819; /* = 819/1024 (BICTCP_BETA_SCALE) */
+static int beta __read_mostly = 717; /* = 717/1024 (BICTCP_BETA_SCALE) */
static int initial_ssthresh __read_mostly;
static int bic_scale __read_mostly = 41;
static int tcp_friendliness __read_mostly = 1;
/* Note parameters that are used for precomputing scale factors are read-only */
module_param(fast_convergence, int, 0644);
MODULE_PARM_DESC(fast_convergence, "turn on/off fast convergence");
-module_param(max_increment, int, 0644);
-MODULE_PARM_DESC(max_increment, "Limit on increment allowed during binary search");
-module_param(beta, int, 0444);
+module_param(beta, int, 0644);
MODULE_PARM_DESC(beta, "beta for multiplicative increase");
module_param(initial_ssthresh, int, 0644);
MODULE_PARM_DESC(initial_ssthresh, "initial value of slow start threshold");
static inline void bictcp_update(struct bictcp *ca, u32 cwnd)
{
u64 offs;
- u32 delta, t, bic_target, min_cnt, max_cnt;
+ u32 delta, t, bic_target, max_cnt;
ca->ack_cnt++; /* count the number of ACKs */
ca->cnt = 100 * cwnd; /* very small increment*/
}
- if (ca->delay_min > 0) {
- /* max increment = Smax * rtt / 0.1 */
- min_cnt = (cwnd * HZ * 8)/(10 * max_increment * ca->delay_min);
-
- /* use concave growth when the target is above the origin */
- if (ca->cnt < min_cnt && t >= ca->bic_K)
- ca->cnt = min_cnt;
- }
-
- /* slow start and low utilization */
- if (ca->loss_cwnd == 0) /* could be aggressive in slow start */
- ca->cnt = 50;
-
/* TCP Friendly */
if (tcp_friendliness) {
u32 scale = beta_scale;
ca->cnt = 1;
}
-
-/* Keep track of minimum rtt */
-static inline void measure_delay(struct sock *sk)
-{
- const struct tcp_sock *tp = tcp_sk(sk);
- struct bictcp *ca = inet_csk_ca(sk);
- u32 delay;
-
- /* No time stamp */
- if (!(tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr) ||
- /* Discard delay samples right after fast recovery */
- (s32)(tcp_time_stamp - ca->epoch_start) < HZ)
- return;
-
- delay = (tcp_time_stamp - tp->rx_opt.rcv_tsecr)<<3;
- if (delay == 0)
- delay = 1;
-
- /* first time call or link delay decreases */
- if (ca->delay_min == 0 || ca->delay_min > delay)
- ca->delay_min = delay;
-}
-
-static void bictcp_cong_avoid(struct sock *sk, u32 ack,
- 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);
- if (data_acked)
- measure_delay(sk);
-
if (!tcp_is_cwnd_limited(sk, in_flight))
return;
/* Track delayed acknowledgment ratio using sliding window
* ratio = (15*ratio + sample) / 16
*/
-static void bictcp_acked(struct sock *sk, u32 cnt, ktime_t last)
+static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt_us)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
+ struct bictcp *ca = inet_csk_ca(sk);
+ u32 delay;
- if (cnt > 0 && icsk->icsk_ca_state == TCP_CA_Open) {
- struct bictcp *ca = inet_csk_ca(sk);
+ if (icsk->icsk_ca_state == TCP_CA_Open) {
cnt -= ca->delayed_ack >> ACK_RATIO_SHIFT;
ca->delayed_ack += cnt;
}
-}
+ /* Some calls are for duplicates without timetamps */
+ if (rtt_us < 0)
+ return;
+
+ /* Discard delay samples right after fast recovery */
+ if ((s32)(tcp_time_stamp - ca->epoch_start) < HZ)
+ return;
+
+ delay = usecs_to_jiffies(rtt_us) << 3;
+ if (delay == 0)
+ delay = 1;
+
+ /* first time call or link delay decreases */
+ if (ca->delay_min == 0 || ca->delay_min > delay)
+ ca->delay_min = delay;
+}
static struct tcp_congestion_ops cubictcp = {
.init = bictcp_init,
MODULE_AUTHOR("Sangtae Ha, Stephen Hemminger");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("CUBIC TCP");
-MODULE_VERSION("2.1");
+MODULE_VERSION("2.2");