On Wed, Sep 23, 2020 at 2:13 PM Jonathan Morton <chromati...@gmail.com> wrote: > It fits my mental model, yes, though obviously the ideal would be to > recognise that the xbox is a singular machine. Are you seeing a larger > disparity than that? If so, is it even larger than four connections would > justify without host-fairness?
Thanks Jonathan, Unfortunately I fear I've been running an improperly configured cake all this time-- leave it to me to take a piece of cake and mess it up :) I should say, even with it being possibly misconfigured, it has still worked amazingly well for me! I have no end of gratitude for y'alls work -- So taking your advice, with my cake properly configured, the answer is no -- it looks like host-fairness is working correctly -- with a notable exception -- read on for details... I was using these probably wrong settings: WAN: besteffort bandwidth $UPBANDWIDTH internet nat egress ethernet LAN: besteffort bandwidth $BANDWIDTH internet nat ingress ethernet So, I was using triple-isolate instead of the correct src/dest isolation options per NIC, and I was using "nat" on the LAN side, which may have been further breaking host isolation as per the openwrt wiki: "don't add the nat option on LAN interfaces (this option should only be used in the WAN interface) or Per-Host Isolation stops working" - https://openwrt.org/docs/guide-user/network/traffic-shaping/sqm-details I changed my configuration to: $WAN handle 1: root cake besteffort bandwidth $UPBANDWIDTH internet nat egress dual-srchost ethernet $LAN handle 1: root cake besteffort bandwidth $BANDWIDTH internet ingress dual-dsthost ethernet So: root@OpenWrt:~# tc -s qdisc | grep cake qdisc cake 1: dev eth1 root refcnt 2 bandwidth 20Mbit besteffort dual-srchost nat nowash no-ack-filter split-gso rtt 100.0ms noatm overhead 38 mpu 84 qdisc cake 1: dev eth0 root refcnt 2 bandwidth 40Mbit besteffort dual-dsthost nonat nowash ingress no-ack-filter split-gso rtt 100.0ms noatm overhead 38 mpu 84 WAN: * nat option enabled * egress option (default) enabled * dual-srchost LAN: * nat option disabled (default) * ingress option enabled * dual-dsthost This worked well, but I ran into a bizarre issue: My xbox FPS gaming UDP stream would start at a low latency (even while other systems were doing bulk downloads), but after some time, the latency went from a steady 30ms (+/- <10ms for jitter) to over 100ms ! 100ms is of course notably the default cake rtt parameter. Resetting cake (tc del and then tc add again) fixed this; the same stream's latency went back down to about 30ms. This gaming stream uses well under 512kbps down and less than half that up, normally. This is worrisome! My use-case may be an edge case, as I have AT&T gigabit fiber but I limit it to 40mbit with cake, since empirically that's the highest throughput I've found that I can use while also maintaining the low jitter / latency over wifi. So certainly the WAN NIC is getting a lot of traffic that cake on the LAN NIC is throwing away. That is, there is basically always a large number of bytes in LAN cake's backlog. For now I've solved this by using the "prio" tc qdisc such that xbox traffic bypasses cake, and all other traffic goes thru cake. Is this a known issue at all? I was quite surprised to see this behaviour. Let me know if I can help debug this. It likely only happens when multiple other hosts are doing bulk downloads / video streaming. Thanks, Dan _______________________________________________ Bloat mailing list Bloat@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/bloat
