Re: simplify microsecond rtt sampling

[John Heffner]

Sigh.  Here's one that's not corrupted.  And for the record:

This changes the microsecond RTT sampling so that samples are taken in 
the same way that RTT samples are taken for the RTO calculator: on the 
last segment acknowledged, and only when the segment hasn't been 
retransmitted.


Signed-off-by: John Heffner <[EMAIL PROTECTED]>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index b5521a9..d0f6bd6 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2228,13 +2228,12 @@ static int tcp_tso_acked(struct sock *sk
        return acked;
 }
 
-static u32 tcp_usrtt(const struct sk_buff *skb)
+static u32 tcp_usrtt(struct timeval *tv)
 {
-       struct timeval tv, now;
+       struct timeval now;
 
        do_gettimeofday(&now);
-       skb_get_timestamp(skb, &tv);
-       return (now.tv_sec - tv.tv_sec) * 1000000 + (now.tv_usec - tv.tv_usec);
+       return (now.tv_sec - tv->tv_sec) * 1000000 + (now.tv_usec - 
tv->tv_usec);
 }
 
 /* Remove acknowledged frames from the retransmission queue. */
@@ -2249,6 +2248,7 @@ static int tcp_clean_rtx_queue(struct so
        u32 pkts_acked = 0;
        void (*rtt_sample)(struct sock *sk, u32 usrtt)
                = icsk->icsk_ca_ops->rtt_sample;
+       struct timeval tv;
 
        while ((skb = skb_peek(&sk->sk_write_queue)) &&
               skb != sk->sk_send_head) {
@@ -2297,8 +2297,7 @@ static int tcp_clean_rtx_queue(struct so
                                seq_rtt = -1;
                        } else if (seq_rtt < 0) {
                                seq_rtt = now - scb->when;
-                               if (rtt_sample)
-                                       (*rtt_sample)(sk, tcp_usrtt(skb));
+                               skb_get_timestamp(skb, &tv);
                        }
                        if (sacked & TCPCB_SACKED_ACKED)
                                tp->sacked_out -= tcp_skb_pcount(skb);
@@ -2311,8 +2310,7 @@ static int tcp_clean_rtx_queue(struct so
                        }
                } else if (seq_rtt < 0) {
                        seq_rtt = now - scb->when;
-                       if (rtt_sample)
-                               (*rtt_sample)(sk, tcp_usrtt(skb));
+                       skb_get_timestamp(skb, &tv);
                }
                tcp_dec_pcount_approx(&tp->fackets_out, skb);
                tcp_packets_out_dec(tp, skb);
@@ -2324,6 +2322,8 @@ static int tcp_clean_rtx_queue(struct so
        if (acked&FLAG_ACKED) {
                tcp_ack_update_rtt(sk, acked, seq_rtt);
                tcp_ack_packets_out(sk, tp);
+               if (rtt_sample && !(acked & FLAG_RETRANS_DATA_ACKED))
+                       (*rtt_sample)(sk, tcp_usrtt(&tv));
 
                if (icsk->icsk_ca_ops->pkts_acked)
                        icsk->icsk_ca_ops->pkts_acked(sk, pkts_acked);