Hi Jonathan, Thanks for the response - this is really helpful. As I said in my original note, I'm casting about for usable advice that we can offer to people today. I want it to be unarguably true, and I want to understand the nuances so that I don't get tripped up by Gotcha's. I'm currently focussed on OpenWrt, as that's a platform where it's easy to roll out fq_codel in current builds simply by downloading a couple packages. I'll work on a draft note with recommendations for OpenWrt and send it past the list for comments. Thanks again. Rich On Apr 9, 2015, at 6:02 PM, Jonathan Morton wrote: > >> On 10 Apr, 2015, at 00:35, Rich Brown wrote: >> >> - Why do we provide an HTB-based shaper in simple.qos and simplest.qos? >> - Do the shapers in these sqm-scripts actually limit bandwidth for various kinds of traffic? Might that not leave unused bandwidth? >> - Or do they just shunt certain packets to higher or lower priority fq_codel tiers/bands/levels (terminology used in Dave's note below)? >> - And if the latter, how does the "link" (I'm not sure of the proper term) know which of the tiers/bands/levels to dequeue next? > > The short answer is: because cake isn’t out in the real world yet. We’re working on it. > > HTB and IFB as used in those scripts is a stopgap solution, to take control of the bottleneck queue so that fq_codel can work on it. Cake includes a shaper which does the job more effectively and more efficiently. > > Ultimately, what we’d like is for fq_codel (or even something as sophisticated as cake) to be implemented in the *actual* bottleneck queues, so that artificially taking control of the bottleneck isn’t necessary. > >> I'll state up front that I'm not entirely clear on the distinction between shapers, qdisc's, IFBs, etc. But I'm groping around for a simple, clear recommendation for what we should tell people to do so they can: >> a) Make their router work very well, with minimal latency >> b) Spend their time more usefully than tweaking QoS/priority settings (for example, by actually playing the game that whose lag you're trying to minimize :-) > > If they’ve got a router with the sqm-scripts installed, use those and follow the directions. The implementation is a little messy, but it works and it keeps things simple for the user. > > When cake arrives, the implementation will get simpler and more efficient. > > - Jonathan Morton >