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authorEric Dumazet <edumazet@google.com>2015-02-26 14:10:20 -0800
committerDavid S. Miller <davem@davemloft.net>2015-02-28 15:10:39 -0500
commita0ea700e4095e26a8e291374757dd29519900f18 (patch)
tree5dc19465848a991d8baf2ac3cac3079c92baef5f
parent50c8339e9299aaf09e48c8f94de39baec638c874 (diff)
downloadop-kernel-dev-a0ea700e4095e26a8e291374757dd29519900f18.zip
op-kernel-dev-a0ea700e4095e26a8e291374757dd29519900f18.tar.gz
tcp: tso: allow CA_CWR state in tcp_tso_should_defer()
Another TCP issue is triggered by ECN. Under pressure, receiver gets ECN marks, and send back ACK packets with ECE TCP flag. Senders enter CA_CWR state. In this state, tcp_tso_should_defer() is short cut : if (icsk->icsk_ca_state != TCP_CA_Open) goto send_now; This means that about all ACK packets we receive are triggering a partial send, and because cwnd is kept small, we can only send a small amount of data for each incoming ACK, which in return generate more ACK packets. Allowing CA_Open and CA_CWR states to enable TSO defer in tcp_tso_should_defer() brings performance back : TSO autodefer has more chance to defer under pressure. This patch increases TSO and LRO/GRO efficiency back to normal levels, and does not impact overall ECN behavior. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_output.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 5f4fb4d..8bbd86c 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1762,7 +1762,7 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
goto send_now;
- if (icsk->icsk_ca_state != TCP_CA_Open)
+ if (!((1 << icsk->icsk_ca_state) & (TCPF_CA_Open | TCPF_CA_CWR)))
goto send_now;
/* Avoid bursty behavior by allowing defer
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