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/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);