> Takeaways (see attached plots): > > - The MTU scaling does indeed give a nice benefit in egress mode > "tcp-download-totals" plot. From just over 6 Mbps to just over 8 Mbps > of goodput on the 10 Mbit link. There is not a large difference > between 2MTU and 4MTU, except that 4MTU hurts inter-flow latency > somewhat. > > - The effect for upload flows (where Cake is before the bottleneck; > 10mbit-upload.png) is negligible. > > - The MTU scaling really hurts TCP RTT (intra-flow latency; > tcp-upload-tcprtt-10mbit.png and rrul-tcprtt.png). > > - For bidirectional traffic the combined effect is also negligible. > > > Based on all this, I propose we change the scaling mechanism so that it > is only active in egress mode, and change it from 4 MTUs to 2. I'll > merge Kevin's patch to do this unless someone complains loudly :) > > If you want me to run other tests, let me know.
I'm not actually sure what you've measured here - unless you've somehow managed to swap "ingress" with "egress" mode in a strange manner. I don't see any systematic measurement of the different MTU scales in ingress mode in your results, which makes your assertion that it should only be active in egress mode rather odd. - Jonathan Morton _______________________________________________ Cake mailing list [email protected] https://lists.bufferbloat.net/listinfo/cake
