Mikael Abrahamsson <[email protected]> writes: > To me, FQ is important especially for lower speeds. This also maps > well into the CPU based nature of FQ (that it's hard to do in > "silicon").
Well my research has been mainly focused on the consumer / edge case. I.e. things a Linux box can drive in hardware, so up to 100Mbit to a Gbit depending on the size of the box. In these cases, fq_codel adds no measurable overhead compared to the CPU load of just pushing the packets. > We're not going to see FQ_CODEL on a 200 interface large router > designed to push 100 gigabit/s of traffic, at least not in any > interesting price point. Maybe not; but note that recent work in the Linux kernel makes it quite capable of pushing 40GigE, and I believe sched_fq (which does 'real' fairness queueing with a queue per flow, not hash buckets as fq_codel does) has been shown to scale to millions of concurrent flows. > Can we do bidirectional traffic FQ_CODEL on the CPE to try to achieve > basically zero loss in the AR policer for any normal kind of use > scenario using TCP. I have not seen any simulations looking at this. Well this is basically what we're doing with the SQM scripts in CeroWRT: put a software rate limiter in the CPE and configure it to a slightly lower value than whatever the cable/DSL modem runs at. This works quite well, but the software rate limiter is fairly CPU hungry, so small boxes struggle. I had to substitute a full x86 box for my Netgear router to run at 100Mbit for my home connection. > Because my belief is that even though we might say we love FQ here, > we're not going to see high speed FQ on higher end ISP aggregation > routers. So if we want FQ, we're going to have to do it in the CPEs. Well OpenWRT turns on fq_codel by default now. :) And yeah, I'm not holding by breath for big iron vendors to include fq_codel in their products. But that doesn't mean it can't go into CPEs. And end hosts and access points. And inside tunnels (VPN daemons for instance). -Toke _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
