| Message ID | 1404155389-22927-1-git-send-email-ncardwell@google.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Mon, Jun 30, 2014 at 10:09 PM, Neal Cardwell <ncardwell@google.com> wrote: > 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. > Acked-by: Octavian Purdila <octavian.purdila@intel.com> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Neal Cardwell <ncardwell@google.com> Date: Mon, 30 Jun 2014 15:09:49 -0400 > 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 <ncardwell@google.com> > Signed-off-by: Yuchung Cheng <ycheng@google.com> Applied, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/net/tcp.h b/include/net/tcp.h index 0d5389a..c9a75db 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; diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 5dfebd2..52d0f6a 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -838,8 +838,6 @@ static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst, ireq->ir_rmt_addr, ireq->opt); err = net_xmit_eval(err); - if (!tcp_rsk(req)->snt_synack && !err) - tcp_rsk(req)->snt_synack = tcp_time_stamp; } return err; diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index bc24ee2..a97c955 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -498,8 +498,6 @@ static int tcp_v6_send_synack(struct sock *sk, struct dst_entry *dst, skb_set_queue_mapping(skb, queue_mapping); err = ip6_xmit(sk, skb, fl6, np->opt, np->tclass); err = net_xmit_eval(err); - if (!tcp_rsk(req)->snt_synack && !err) - tcp_rsk(req)->snt_synack = tcp_time_stamp; } done:
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 <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Cc: Octavian Purdila <octavian.purdila@intel.com> Cc: Jerry Chu <hkchu@google.com> --- include/net/tcp.h | 2 +- net/ipv4/tcp_ipv4.c | 2 -- net/ipv6/tcp_ipv6.c | 2 -- 3 files changed, 1 insertion(+), 5 deletions(-)