Re: way of figuring out total number of retransmitted packets on a TCP socket?

["David S. Miller" <davem@xxxxxxxxxxxxx>]

Please give this 2.6.x patch a spin:

# This is a BitKeeper generated diff -Nru style patch.
#
# ChangeSet
#   2004/10/20 21:21:01-07:00 davem@xxxxxxxxxxxxxxxxxx 
#   [TCP]: Add total num retransmits accounting.
#   
#   Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
# 
# net/ipv4/tcp_output.c
#   2004/10/20 21:20:29-07:00 davem@xxxxxxxxxxxxxxxxxx +2 -0
#   [TCP]: Add total num retransmits accounting.
# 
# net/ipv4/tcp_diag.c
#   2004/10/20 21:20:29-07:00 davem@xxxxxxxxxxxxxxxxxx +2 -0
#   [TCP]: Add total num retransmits accounting.
# 
# include/linux/tcp.h
#   2004/10/20 21:20:29-07:00 davem@xxxxxxxxxxxxxxxxxx +4 -0
#   [TCP]: Add total num retransmits accounting.
# 
diff -Nru a/include/linux/tcp.h b/include/linux/tcp.h
--- a/include/linux/tcp.h       2004-10-20 21:21:21 -07:00
+++ b/include/linux/tcp.h       2004-10-20 21:21:21 -07:00
@@ -186,6 +186,8 @@
 
        __u32   tcpi_rcv_rtt;
        __u32   tcpi_rcv_space;
+
+       __u32   tcpi_total_retrans;
 };
 
 #ifdef __KERNEL__
@@ -363,6 +365,8 @@
        __u8    pending;        /* Scheduled timer event        */
        __u8    urg_mode;       /* In urgent mode               */
        __u32   snd_up;         /* Urgent pointer               */
+
+       __u32   total_retrans;  /* Total retransmits for entire connection */
 
        /* The syn_wait_lock is necessary only to avoid proc interface having
         * to grab the main lock sock while browsing the listening hash
diff -Nru a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
--- a/net/ipv4/tcp_diag.c       2004-10-20 21:21:21 -07:00
+++ b/net/ipv4/tcp_diag.c       2004-10-20 21:21:21 -07:00
@@ -105,6 +105,8 @@
 
        info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
        info->tcpi_rcv_space = tp->rcvq_space.space;
+
+       info->tcpi_total_retrans = tp->total_retrans;
 }
 
 static int tcpdiag_fill(struct sk_buff *skb, struct sock *sk,
diff -Nru a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
--- a/net/ipv4/tcp_output.c     2004-10-20 21:21:21 -07:00
+++ b/net/ipv4/tcp_output.c     2004-10-20 21:21:22 -07:00
@@ -1106,6 +1106,8 @@
                /* Update global TCP statistics. */
                TCP_INC_STATS(TCP_MIB_RETRANSSEGS);
 
+               tp->total_retrans++;
+
 #if FASTRETRANS_DEBUG > 0
                if (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) {
                        if (net_ratelimit())