jamal wrote: > > On Tue, 17 Sep 2002, Ben Greear wrote: > > >>I have a program that sends and receives UDP packets with 32-bit sequence >>numbers. I can detect OOO packets if they fit into the last 10 packets >>received. If they are farther out of order than that, the code treats >>them as dropped.... >> > > > So let me understand this: > You have a packet going out eth0 looped back to eth0 and you are seeing I go out eth2 and come in eth3, both e1000 copper nics. > reordering? What sort of things are happening from departure at udp socket > to arrival on the other side? Are you doing anything funky yourself or > it is all kernel? I see reordering on regular old socket calls from user space, and I see the same thing with pktgen packets as well (which clears the stack of fault). For user space, I am binding to source IP, setting SO_BINDTODEVICE, and O_NONBLOCK. Nothing overly weird I believe. pktgen has its own ways, basically it grabs the pkts in the dev.c receive method near where the bridging code grabs it's packets... I see no reordering at all with tulip 4-port nics and single processor machines. > > >>I used smp_afinity to tie a NIC to a CPU, and the napi patch for 2.4.20-pre7. > > > Did you get reordering with affinity? Yes. I'm not sure I tried affinity w/out NAPI though. I definately tried it with NAPI and saw reordering. > > >>When sending and receiving 250Mbps of UDP/IP traffic (sending over cross-over >>cable to other NIC on same machine), I see the occasional OOO packet. I also >>see bogus dropped packets, which means sometimes the order is off by 10 or more >>packets.... > > > A lot of shit is happening at that rate in particular with PCI bus. If > i understood correctly a packet crosses the bus about 4 times? Two times I believe, but I'm sending in both directions, so there is about 1Gbps across the bus, not even counting the UDP, IP, and Ethernet headers. > > >>The other fun thing about this setup is that after running around 65 billion bytes >>with this test, the machine crashes with an OOPs. > > > No clue whats going on - probably a race somewhere and cant help since > i dont have this NIC but if you get Robert excited he might be able to > help you. He seems moderately interested, suggested I try the one in 2.5.[latest]. I'll be able to do that next week, assuming it's trivial to compile it for 2.4.19.... Thanks, Ben -- Ben Greear <greearb@candelatech.com> <Ben_Greear AT excite.com> President of Candela Technologies Inc http://www.candelatech.com ScryMUD: http://scry.wanfear.com http://scry.wanfear.com/~greear - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
