linux-2.6-720-undo-rttzero.patch

   1 diff -Ndur linux-2.6.32-orig/net/ipv4/tcp_input.c linux-2.6.32-undorttzero/net/ipv4/tcp_input.c
   2 --- linux-2.6.32-orig/net/ipv4/tcp_input.c      2013-06-05 15:47:10.551009408 -0400
   3 +++ linux-2.6.32-undorttzero/net/ipv4/tcp_input.c       2013-06-05 15:49:32.458996663 -0400
   4 @@ -5783,9 +5783,11 @@
   5
   6                                 /* tcp_ack considers this ACK as duplicate
   7                                  * and does not calculate rtt.
   8 -                                * Force it here.
   9 +                                * Fix it at least with timestamps.
  10                                  */
  11 -                               tcp_ack_update_rtt(sk, 0, 0);
  12 +                               if (tp->rx_opt.saw_tstamp &&
  13 +                                       tp->rx_opt.rcv_tsecr && !tp->srtt)
  14 +                                               tcp_ack_saw_tstamp(sk, 0);
  15
  16                                 if (tp->rx_opt.tstamp_ok)
  17                                         tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;