[TCP]: Appropriate Byte Count support
This is an updated version of the RFC3465 ABC patch originally
for Linux 2.6.11-rc4 by Yee-Ting Li. ABC is a way of counting
bytes ack'd rather than packets when updating congestion control.
The orignal ABC described in the RFC applied to a Reno style
algorithm. For advanced congestion control there is little
change after leaving slow start.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 6526856..01444a0 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -645,6 +645,14 @@
.proc_handler = &proc_tcp_congestion_control,
.strategy = &sysctl_tcp_congestion_control,
},
+ {
+ .ctl_name = NET_TCP_ABC,
+ .procname = "tcp_abc",
+ .data = &sysctl_tcp_abc,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
{ .ctl_name = 0 }
};
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 72b7c22..cfaf761 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1669,6 +1669,7 @@
tp->packets_out = 0;
tp->snd_ssthresh = 0x7fffffff;
tp->snd_cwnd_cnt = 0;
+ tp->bytes_acked = 0;
tcp_set_ca_state(sk, TCP_CA_Open);
tcp_clear_retrans(tp);
inet_csk_delack_init(sk);
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 6d3e883..c7cc62c 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -192,17 +192,26 @@
/* In "safe" area, increase. */
if (tp->snd_cwnd <= tp->snd_ssthresh)
tcp_slow_start(tp);
- else {
- /* In dangerous area, increase slowly.
- * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd
- */
- if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
- if (tp->snd_cwnd < tp->snd_cwnd_clamp)
- tp->snd_cwnd++;
- tp->snd_cwnd_cnt = 0;
- } else
- tp->snd_cwnd_cnt++;
- }
+
+ /* In dangerous area, increase slowly. */
+ else if (sysctl_tcp_abc) {
+ /* RFC3465: Apppriate Byte Count
+ * increase once for each full cwnd acked
+ */
+ if (tp->bytes_acked >= tp->snd_cwnd*tp->mss_cache) {
+ tp->bytes_acked -= tp->snd_cwnd*tp->mss_cache;
+ if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+ tp->snd_cwnd++;
+ }
+ } else {
+ /* In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd */
+ if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
+ if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+ tp->snd_cwnd++;
+ tp->snd_cwnd_cnt = 0;
+ } else
+ tp->snd_cwnd_cnt++;
+ }
}
EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index e4306565..4cb5e6f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -89,6 +89,7 @@
int sysctl_tcp_nometrics_save;
int sysctl_tcp_moderate_rcvbuf = 1;
+int sysctl_tcp_abc = 1;
#define FLAG_DATA 0x01 /* Incoming frame contained data. */
#define FLAG_WIN_UPDATE 0x02 /* Incoming ACK was a window update. */
@@ -1247,6 +1248,7 @@
tp->snd_cwnd_cnt = 0;
tp->snd_cwnd_stamp = tcp_time_stamp;
+ tp->bytes_acked = 0;
tcp_clear_retrans(tp);
/* Push undo marker, if it was plain RTO and nothing
@@ -1904,6 +1906,7 @@
TCP_ECN_queue_cwr(tp);
}
+ tp->bytes_acked = 0;
tp->snd_cwnd_cnt = 0;
tcp_set_ca_state(sk, TCP_CA_Recovery);
}
@@ -2310,6 +2313,9 @@
if (before(ack, prior_snd_una))
goto old_ack;
+ if (sysctl_tcp_abc && icsk->icsk_ca_state < TCP_CA_CWR)
+ tp->bytes_acked += ack - prior_snd_una;
+
if (!(flag&FLAG_SLOWPATH) && after(ack, prior_snd_una)) {
/* Window is constant, pure forward advance.
* No more checks are required.
@@ -4370,6 +4376,7 @@
EXPORT_SYMBOL(sysctl_tcp_ecn);
EXPORT_SYMBOL(sysctl_tcp_reordering);
+EXPORT_SYMBOL(sysctl_tcp_abc);
EXPORT_SYMBOL(tcp_parse_options);
EXPORT_SYMBOL(tcp_rcv_established);
EXPORT_SYMBOL(tcp_rcv_state_process);
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index b1a63b2..9203a21 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -380,6 +380,7 @@
*/
newtp->snd_cwnd = 2;
newtp->snd_cwnd_cnt = 0;
+ newtp->bytes_acked = 0;
newtp->frto_counter = 0;
newtp->frto_highmark = 0;
