[TCP] H-TCP: Account for delayed-ACKs
Account for delayed-ACKs in H-TCP.
Delayed-ACKs cause H-TCP to be less aggressive than its design calls
for. It is especially true when the receiver is a Linux machine where
the average delayed ack is over 3 packets with values of 7 not unheard
of.
Signed-off-By: Baruch Even <baruch@ev-en.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_htcp.c b/net/ipv4/tcp_htcp.c
index fda2f87..ac19252 100644
--- a/net/ipv4/tcp_htcp.c
+++ b/net/ipv4/tcp_htcp.c
@@ -29,7 +29,8 @@
u8 modeswitch; /* Delay modeswitch until we had at least one congestion event */
u8 ccount; /* Number of RTTs since last congestion event */
u8 undo_ccount;
- u16 packetcount;
+ u16 pkts_acked;
+ u32 packetcount;
u32 minRTT;
u32 maxRTT;
u32 snd_cwnd_cnt2;
@@ -92,6 +93,12 @@
struct htcp *ca = inet_csk_ca(sk);
u32 now = tcp_time_stamp;
+ if (icsk->icsk_ca_state == TCP_CA_Open)
+ ca->pkts_acked = pkts_acked;
+
+ if (!use_bandwidth_switch)
+ return;
+
/* achieved throughput calculations */
if (icsk->icsk_ca_state != TCP_CA_Open &&
icsk->icsk_ca_state != TCP_CA_Disorder) {
@@ -217,20 +224,24 @@
measure_rtt(sk);
/* keep track of number of round-trip times since last backoff event */
- if (ca->snd_cwnd_cnt2++ > tp->snd_cwnd) {
+ if (ca->snd_cwnd_cnt2 >= tp->snd_cwnd) {
ca->ccount++;
- ca->snd_cwnd_cnt2 = 0;
+ ca->snd_cwnd_cnt2 -= tp->snd_cwnd;
htcp_alpha_update(ca);
- }
+ } else
+ ca->snd_cwnd_cnt2 += ca->pkts_acked;
/* In dangerous area, increase slowly.
* In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd
*/
- if ((tp->snd_cwnd_cnt++ * ca->alpha)>>7 >= tp->snd_cwnd) {
+ if ((tp->snd_cwnd_cnt * ca->alpha)>>7 >= tp->snd_cwnd) {
if (tp->snd_cwnd < tp->snd_cwnd_clamp)
tp->snd_cwnd++;
tp->snd_cwnd_cnt = 0;
- }
+ } else
+ tp->snd_cwnd_cnt += ca->pkts_acked;
+
+ ca->pkts_acked = 1;
}
}
@@ -249,6 +260,7 @@
memset(ca, 0, sizeof(struct htcp));
ca->alpha = ALPHA_BASE;
ca->beta = BETA_MIN;
+ ca->pkts_acked = 1;
}
static void htcp_state(struct sock *sk, u8 new_state)
@@ -278,8 +290,6 @@
{
BUG_ON(sizeof(struct htcp) > ICSK_CA_PRIV_SIZE);
BUILD_BUG_ON(BETA_MIN >= BETA_MAX);
- if (!use_bandwidth_switch)
- htcp.pkts_acked = NULL;
return tcp_register_congestion_control(&htcp);
}