diff options
| author | Yuchung Cheng <ycheng@google.com> | 2013-07-22 16:20:45 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-07-22 17:53:42 -0700 |
| commit | 375fe02c91792917aa26d68a87ab110d1937f44e (patch) | |
| tree | 2a6c1205f6b136f7ac55f191912b386a0f3b2491 /net/ipv4/tcp_input.c | |
| parent | c3f51d5f387b552b9d9fd7f41e19b84929712f82 (diff) | |
| download | lwn-375fe02c91792917aa26d68a87ab110d1937f44e.tar.gz lwn-375fe02c91792917aa26d68a87ab110d1937f44e.zip | |
tcp: consolidate SYNACK RTT sampling
The first patch consolidates SYNACK and other RTT measurement to use a
central function tcp_ack_update_rtt(). A (small) bonus is now SYNACK
RTT measurement happens after PAWS check, potentially reducing the
impact of RTO seeding on bad TCP timestamps values.
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 28af45abe062..b531710596ec 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2853,6 +2853,17 @@ static inline void tcp_ack_update_rtt(struct sock *sk, const int flag, tcp_ack_no_tstamp(sk, seq_rtt, flag); } +/* Compute time elapsed between (last) SYNACK and the ACK completing 3WHS. */ +static void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req) +{ + struct tcp_sock *tp = tcp_sk(sk); + s32 seq_rtt = -1; + + if (tp->lsndtime && !tp->total_retrans) + seq_rtt = tcp_time_stamp - tp->lsndtime; + tcp_ack_update_rtt(sk, FLAG_SYN_ACKED, seq_rtt); +} + static void tcp_cong_avoid(struct sock *sk, u32 ack, u32 in_flight) { const struct inet_connection_sock *icsk = inet_csk(sk); @@ -5624,9 +5635,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, * so release it. */ if (req) { - tcp_synack_rtt_meas(sk, req); tp->total_retrans = req->num_retrans; - reqsk_fastopen_remove(sk, req, false); } else { /* Make sure socket is routed, for correct metrics. */ @@ -5651,6 +5660,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, tp->snd_una = TCP_SKB_CB(skb)->ack_seq; tp->snd_wnd = ntohs(th->window) << tp->rx_opt.snd_wscale; tcp_init_wl(tp, TCP_SKB_CB(skb)->seq); + tcp_synack_rtt_meas(sk, req); if (tp->rx_opt.tstamp_ok) tp->advmss -= TCPOLEN_TSTAMP_ALIGNED; |