Hi Andy, Andy Furniss schrieb: > Arnd Hannemann wrote: > >> >> Could you explain this a bit more in detail, why does it not work on >> root of an device? >> I tried it with various configurations and indeed it does not work. >> Even if the incoming interface is much faster then the outgoing >> interface I can't get the red queue to drop or mark packets. Packets >> are always dropped somewhere else? > > I suppose exactly what happens depends on the device drivers and the > type of device. On my 100mbit eth I probably could get RED to work a > bit, but I would have to fill a buffer of about 300 MTU size packets > first, so it would never be right as such. > I see you have wireless, I don't have any wireless, but I guess the > drivers may drop/shape without ever backlogging the root device - or > maybe you don't generate enough traffic to fill the buffer. ah, I see. I think now I understand more how it works. The kernel hands down the skb to the device driver, and for RED to work on the root device, the device driver has to explicitly handle the skb, back, or at least communicate that it is busy. > > > I tried again using the bandwidth parameter (which I called rate > earlier) and with bigger buffers at 5mbit using 5 netperfs I can get > nearly no drops. (if you run multiple netperfs from a script make sure > and addresses are in /etc/hosts and 0.0.0.0 is aswell as it seems to > insist on doing dns lookups - which can delay some of them) > > I guess wifi like eth uses arp - so using tbf on root may drop some > arp, but just to test I put it on root of my 100mbit eth. > > tc qdisc add dev eth0 root handle 1: tbf rate 5mbit burst 2k limit 100k > > tc qdisc add dev eth0 parent 1: red limit 100kb min 10kb max 60kb > avpkt 1000 burst 12 probability .2 bandwidth 5mbit ecn > > After 100 seconds of traffic - > > qdisc tbf 1: rate 5000Kbit burst 2Kb lat 82.7ms > Sent 62495756 bytes 41328 pkt (dropped 1, overlimits 87189 requeues 0) > rate 0bit 0pps backlog 0b 0p requeues 0 > > qdisc red 8002: parent 1: limit 100Kb min 10Kb max 60Kb ecn > Sent 62495756 bytes 41328 pkt (dropped 1, overlimits 2412 requeues > 87189) > rate 0bit 0pps backlog 0b 0p requeues 87189 > marked 2411 early 1 pdrop 0 other 0 > > I wonder if the drop was arp - I also tried again while pinging and > got 7% loss. Pings without ecn gave 13% loss. > > > The same test but without the ecn parameter - > > [root@amd /home/andy/Qos]# tc -s qdisc ls dev eth0 > > qdisc tbf 1: rate 5000Kbit burst 2Kb lat 82.7ms > Sent 62473422 bytes 41315 pkt (dropped 2320, overlimits 90861 > requeues 0) > rate 0bit 0pps backlog 0b 0p requeues 0 > > qdisc red 8001: parent 1: limit 100Kb min 10Kb max 60Kb > Sent 62473422 bytes 41315 pkt (dropped 2320, overlimits 2320 requeues > 90861) > rate 0bit 0pps backlog 0b 0p requeues 90861 > marked 0 early 2320 pdrop 0 other 0 > Andy, thanks a lot for your efforts. Its good to see that in principal ECN really works and can save DROPs ;-) Best regards, Arnd _______________________________________________ LARTC mailing list LARTC@xxxxxxxxxxxxxxx http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc
