tcp: remove Appropriate Byte Count support
TCP Appropriate Byte Count was added by me, but later disabled.
There is no point in maintaining it since it is a potential source
of bugs and Linux already implements other better window protection
heuristics.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.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 2622707..960fd29 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -633,13 +633,6 @@
.proc_handler = proc_tcp_congestion_control,
},
{
- .procname = "tcp_abc",
- .data = &sysctl_tcp_abc,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec,
- },
- {
.procname = "tcp_mtu_probing",
.data = &sysctl_tcp_mtu_probing,
.maxlen = sizeof(int),
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 3ec1f69..2c7e596 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2289,7 +2289,6 @@
tp->packets_out = 0;
tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
tp->snd_cwnd_cnt = 0;
- tp->bytes_acked = 0;
tp->window_clamp = 0;
tcp_set_ca_state(sk, TCP_CA_Open);
tcp_clear_retrans(tp);
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index cdf2e70..019c238 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -317,28 +317,11 @@
snd_cwnd = 1U;
}
- /* RFC3465: ABC Slow start
- * Increase only after a full MSS of bytes is acked
- *
- * TCP sender SHOULD increase cwnd by the number of
- * previously unacknowledged bytes ACKed by each incoming
- * acknowledgment, provided the increase is not more than L
- */
- if (sysctl_tcp_abc && tp->bytes_acked < tp->mss_cache)
- return;
-
if (sysctl_tcp_max_ssthresh > 0 && tp->snd_cwnd > sysctl_tcp_max_ssthresh)
cnt = sysctl_tcp_max_ssthresh >> 1; /* limited slow start */
else
cnt = snd_cwnd; /* exponential increase */
- /* RFC3465: ABC
- * We MAY increase by 2 if discovered delayed ack
- */
- if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache)
- cnt <<= 1;
- tp->bytes_acked = 0;
-
tp->snd_cwnd_cnt += cnt;
while (tp->snd_cwnd_cnt >= snd_cwnd) {
tp->snd_cwnd_cnt -= snd_cwnd;
@@ -378,20 +361,9 @@
/* In "safe" area, increase. */
if (tp->snd_cwnd <= tp->snd_ssthresh)
tcp_slow_start(tp);
-
/* In dangerous area, increase slowly. */
- else if (sysctl_tcp_abc) {
- /* RFC3465: Appropriate 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 {
+ else
tcp_cong_avoid_ai(tp, tp->snd_cwnd);
- }
}
EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index e376aa9..f56bd10 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -98,7 +98,6 @@
int sysctl_tcp_thin_dupack __read_mostly;
int sysctl_tcp_moderate_rcvbuf __read_mostly = 1;
-int sysctl_tcp_abc __read_mostly;
int sysctl_tcp_early_retrans __read_mostly = 2;
#define FLAG_DATA 0x01 /* Incoming frame contained data. */
@@ -2007,7 +2006,6 @@
tp->snd_cwnd_cnt = 0;
tp->snd_cwnd_stamp = tcp_time_stamp;
tp->frto_counter = 0;
- tp->bytes_acked = 0;
tp->reordering = min_t(unsigned int, tp->reordering,
sysctl_tcp_reordering);
@@ -2056,7 +2054,6 @@
tp->snd_cwnd_cnt = 0;
tp->snd_cwnd_stamp = tcp_time_stamp;
- tp->bytes_acked = 0;
tcp_clear_retrans_partial(tp);
if (tcp_is_reno(tp))
@@ -2684,7 +2681,6 @@
struct tcp_sock *tp = tcp_sk(sk);
tp->high_seq = tp->snd_nxt;
- tp->bytes_acked = 0;
tp->snd_cwnd_cnt = 0;
tp->prior_cwnd = tp->snd_cwnd;
tp->prr_delivered = 0;
@@ -2735,7 +2731,6 @@
struct tcp_sock *tp = tcp_sk(sk);
tp->prior_ssthresh = 0;
- tp->bytes_acked = 0;
if (inet_csk(sk)->icsk_ca_state < TCP_CA_CWR) {
tp->undo_marker = 0;
tcp_init_cwnd_reduction(sk, set_ssthresh);
@@ -3417,7 +3412,6 @@
{
tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
tp->snd_cwnd_cnt = 0;
- tp->bytes_acked = 0;
TCP_ECN_queue_cwr(tp);
tcp_moderate_cwnd(tp);
}
@@ -3609,15 +3603,6 @@
if (after(ack, prior_snd_una))
flag |= FLAG_SND_UNA_ADVANCED;
- if (sysctl_tcp_abc) {
- if (icsk->icsk_ca_state < TCP_CA_CWR)
- tp->bytes_acked += ack - prior_snd_una;
- else if (icsk->icsk_ca_state == TCP_CA_Loss)
- /* we assume just one segment left network */
- tp->bytes_acked += min(ack - prior_snd_una,
- tp->mss_cache);
- }
-
prior_fackets = tp->fackets_out;
prior_in_flight = tcp_packets_in_flight(tp);
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index f35f2df..f040928 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -446,7 +446,6 @@
*/
newtp->snd_cwnd = TCP_INIT_CWND;
newtp->snd_cwnd_cnt = 0;
- newtp->bytes_acked = 0;
newtp->frto_counter = 0;
newtp->frto_highmark = 0;