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authorNeal Cardwell <ncardwell@google.com>2015-01-28 20:01:35 -0500
committerDavid S. Miller <davem@davemloft.net>2015-01-28 22:18:37 -0800
commite73ebb0881ea5534ce606c1d71b4ac44db5c6930 (patch)
tree2a20ba5a81c6e85982c4fe3b8ec33ca2cd4b2a96 /net/ipv4/tcp_bic.c
parentMerge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net (diff)
downloadlinux-dev-e73ebb0881ea5534ce606c1d71b4ac44db5c6930.tar.xz
linux-dev-e73ebb0881ea5534ce606c1d71b4ac44db5c6930.zip
tcp: stretch ACK fixes prep
LRO, GRO, delayed ACKs, and middleboxes can cause "stretch ACKs" that cover more than the RFC-specified maximum of 2 packets. These stretch ACKs can cause serious performance shortfalls in common congestion control algorithms that were designed and tuned years ago with receiver hosts that were not using LRO or GRO, and were instead politely ACKing every other packet. This patch series fixes Reno and CUBIC to handle stretch ACKs. This patch prepares for the upcoming stretch ACK bug fix patches. It adds an "acked" parameter to tcp_cong_avoid_ai() to allow for future fixes to tcp_cong_avoid_ai() to correctly handle stretch ACKs, and changes all congestion control algorithms to pass in 1 for the ACKed count. It also changes tcp_slow_start() to return the number of packet ACK "credits" that were not processed in slow start mode, and can be processed by the congestion control module in additive increase mode. In future patches we will fix tcp_cong_avoid_ai() to handle stretch ACKs, and fix Reno and CUBIC handling of stretch ACKs in slow start and additive increase mode. Reported-by: Eyal Perry <eyalpe@mellanox.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_bic.c')
-rw-r--r--net/ipv4/tcp_bic.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/tcp_bic.c b/net/ipv4/tcp_bic.c
index bb395d46a389..c037644eafb7 100644
--- a/net/ipv4/tcp_bic.c
+++ b/net/ipv4/tcp_bic.c
@@ -150,7 +150,7 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
tcp_slow_start(tp, acked);
else {
bictcp_update(ca, tp->snd_cwnd);
- tcp_cong_avoid_ai(tp, ca->cnt);
+ tcp_cong_avoid_ai(tp, ca->cnt, 1);
}
}