Hi, I'm testing Linux 2.6.16-rc1-git4 on a 500Mbps line with 220ms rtt. I'm getting a very strange cwnd history and was wondering if anyone noticed it before and knows why it happens. A graph is attached and you can find a resizable version at http://hamilton.ie/person/baruch/linet/
The changes I have in my tree are only related to tracing the cwnd history (and other details), the only functional change is commenting out the tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp)+1); line in tcp_cwnd_down(), with it the history was flawed but differently. Settings of possible interest: congestion control: htcp ecn: 1 abc: 1 tso: off (performance is very low with it on, on the order of tens of Kbps) sack: 1 (no losses due to the use of ECN) The ECN marking strategy is to mark all packets that fill more than half the buffer, the buffer is set to 40% of the BDP so ECN markings happens at 20% of the BDP. The strange part is where the graph goes up in stairs until some point that it returns to normality and does the normal H-TCP fast increase. Thanks in advance, Baruch
