On Tue, Jul 24, 2018 at 3:33 PM Jonathan Morton wrote: > > On 24 Jul, 2018, at 11:11 pm, Benjamin Cronce wrote: > > > > The problem that I'm getting is by adding my own shaping, a measurable > amount of the benefit of their AQM is lost. While I am limited to Codel, > HFSC+Codel, or FairQ+Codel for now, I am actually doing a worse job of > anti-bufferbloat than my ISP is. Fewer latency spices according to > DSLReports. > > We do know that applying SQM at the entry to the bottleneck link works > much better than at the exit. It's a fundamental principle. > > > That's when I thought of a backpressure-less AQM. Instead of having > backpressure and measuring sojourn time as a function of how long it takes > packets to get scheduled, predict an estimated sojourn time based on the > observed rate of flow, but allow packets to immediately vacate the queue. > The AQM would either mark ECN or drop the packet, but never delay the > packet. > > It's a reasonable idea. The key point is to use a deficit-mode > scheduler/shaper, rather than the credit-mode ones that are common (mainly > TBF/HTB). The latter are why you have such a big, uncontrolled burst from > the ISP in the first place. > > - Jonathan Morton > From what I understand, the ISP is shaping on the core router and they're using whatever algorithm so happens to be implemented. It has been a few years since I last talked to anyone from there and it does seem to be acting differently, so I am not sure if they purposefully made any changes, but when I did talk to them last time, they said they did not do any purposeful configurations to combat bufferbloat and whatever I was seeing was entirely arbitrary. When their shaping was worse, it very much acted like a sliding window in that it pretty much like line rate 1Gb/s through until ~200ms, at which point it started to clamp down very quickly and reach a healthy steady state in ~2 seconds. But during that transition, loss spikes were pretty bad. Now it feels like the window is just much larger. I no longer see it hitting line rate anymore, but it does seems to be capped around 2x provisioned. When I was at 150Mb, It maxed out around 300Mb/s and slowly dropped to 150Mb. Now it maxed out about 500Mb and roughly the same slope down to 250Mb. Here is an example of what I'm seeing https://www.dslreports.com/speedtest/36310277 While there are a few spikes on the download, when running many tests in a row, I see fewer and smaller spikes than if I do my own shaping.