Back in May of last year, I reported this problem, but worked around it at the time by changing the kernel memory settings in the networking stack. I reproduced the problem again today with the previously working kernel memory settings..which is not supprising since I just papered over the bug last time.
The problem is that I set up a TCP connection with bi-directional traffic of around 800Mbps, doing large (20k - 64k writes and reads) between two ports on the same machine (this 2.6.18.2 kernel is tainted with my full patch set, but I also reproduced with only the non-tainted send-to-self patch applied last may on the 2.6.16 kernel, so I assume the bug is not particular to my patch set). At first, all is well, but within 5-10 minutes, the TCP connection will stall and I only see a massive amount of duplicate ACKs on the link. Before, I sometimes saw OOM messages, but this time there are no OOM messages. The system has a two-port pro/1000 fibre NIC, 1GB RAM, kernel 2.6.18.2 + hacks, etc. Stopping and starting the connection allows traffic to flow again (if briefly). Starting a new connection works fine even if the old one is still stalled, so it's not a global memory exhaustion problem. So, I would like to dig into this problem myself since no one else is reporting this type of problem, but I am quite ignorant of the TCP stack implementation. Based on the dup-acks I see on the wire, I assume the TCP state machine is messed up somehow. Could anyone point me to likely places in the TCP stack to start looking for this bug? Thanks, Ben -- Ben Greear <[EMAIL PROTECTED]> Candela Technologies Inc http://www.candelatech.com - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
