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authorStephen Hemminger <shemminger@osdl.org>2005-11-10 17:09:53 -0800
committerDavid S. Miller <davem@davemloft.net>2005-11-10 17:09:53 -0800
commit9772efb970780aeed488c19d8b4afd46c3b484af (patch)
treede016aaa29c8a95e98c7abaa70c8b590160e2886 /net/ipv4/tcp_cong.c
parent7faffa1c7fb9b8e8917e3225d4e2638270c0a48b (diff)
[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>
Diffstat (limited to 'net/ipv4/tcp_cong.c')
-rw-r--r--net/ipv4/tcp_cong.c31
1 files changed, 20 insertions, 11 deletions
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 6d3e883b48f6..c7cc62c8dc12 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -192,17 +192,26 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 rtt, u32 in_flight,
/* 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);