From 86c6a2c75ab97fe31844985169e26aea335432f9 Mon Sep 17 00:00:00 2001 From: Neal Cardwell Date: Mon, 30 Jun 2014 15:09:49 -0400 Subject: tcp: switch snt_synack back to measuring transmit time of first SYNACK Always store in snt_synack the time at which the server received the first client SYN and attempted to send the first SYNACK. Recent commit aa27fc501 ("tcp: tcp_v[46]_conn_request: fix snt_synack initialization") resolved an inconsistency between IPv4 and IPv6 in the initialization of snt_synack. This commit brings back the idea from 843f4a55e (tcp: use tcp_v4_send_synack on first SYN-ACK), which was going for the original behavior of snt_synack from the commit where it was added in 9ad7c049f0f79 ("tcp: RFC2988bis + taking RTT sample from 3WHS for the passive open side") in v3.1. In addition to being simpler (and probably a tiny bit faster), unconditionally storing the time of the first SYNACK attempt has been useful because it allows calculating a performance metric quantifying how long it took to establish a passive TCP connection. Signed-off-by: Neal Cardwell Signed-off-by: Yuchung Cheng Cc: Octavian Purdila Cc: Jerry Chu Acked-by: Octavian Purdila Signed-off-by: David S. Miller --- include/net/tcp.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/net/tcp.h') diff --git a/include/net/tcp.h b/include/net/tcp.h index 0d5389aecf1..c9a75dbba0c 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1093,7 +1093,7 @@ static inline void tcp_openreq_init(struct request_sock *req, req->cookie_ts = 0; tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq; tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; - tcp_rsk(req)->snt_synack = 0; + tcp_rsk(req)->snt_synack = tcp_time_stamp; req->mss = rx_opt->mss_clamp; req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0; ireq->tstamp_ok = rx_opt->tstamp_ok; -- cgit v1.2.3-70-g09d2