From: Eric Dumazet Date: Sun, 26 Jul 2015 07:45:24 +0000 (+0200) Subject: tcp: tso: allow deferring under reordering state X-Git-Tag: v4.3-rc1~96^2~284 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=99d7662a04c4f9822b042f22ae37f8c7355c2d5a;p=linux.git tcp: tso: allow deferring under reordering state While doing experiments with reordering resilience, we found linux senders were not able to send at full speed under reordering, because every incoming SACK was releasing one MSS. This patch removes the limitation, as we did for CWR state in commit a0ea700e409 ("tcp: tso: allow CA_CWR state in tcp_tso_should_defer()") Neal Cardwell had a concern about limited transmit so Yuchung conducted experiments on GFE and found nothing worth adding an extra check on fast path : if (icsk->icsk_ca_state == TCP_CA_Disorder && tcp_sk(sk)->reordering == sysctl_tcp_reordering) goto send_now; Signed-off-by: Eric Dumazet Signed-off-by: Yuchung Cheng Cc: Neal Cardwell Acked-by: Neal Cardwell Signed-off-by: David S. Miller --- diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 71057849593a..7d1efa762b75 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1774,7 +1774,7 @@ 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 (!((1 << icsk->icsk_ca_state) & (TCPF_CA_Open | TCPF_CA_CWR))) + if (icsk->icsk_ca_state >= TCP_CA_Recovery) goto send_now; /* Avoid bursty behavior by allowing defer