Mikael Abrahamsson <[email protected]> writes: > On Thu, 23 Aug 2018, Dave Taht wrote: > >> I should also point out that the kinds of routing latency numbers in >> those blog entries was on very high end intel hardware. It would be >> good to re-run those sort of tests on the armada and others for >> 1,10,100, 1000 routes. Clever complicated algorithms have a tendency >> to bloat icache and cost more than they are worth, fairly often, on >> hardware that typically has 32k i/d caches, and a small L2. > > My testing has been on OpenWrt with 4.14 on intel x86-64. Looking how the > box behaves, I'd say it's limited by context switching / interrupt load, > and not actually by CPU being busy doing "hard work". > > All of the fast routing implementations (snabbswitch, FD.IO/VPP etc) > they take away CPU and devices from Linux, and runs busy-loop with > polling a lot of the time, an never context switching which means L1 > cache is never churned. This is how they become fast. I see potential > to do "XDP offload" of forwarding here, basically doing similar job to > what a hardware packet accelerator does.
Yup, that would help; we see basically 2-3x improvement in routing performance with XDP over the regular stack. Don't think there's XDP support in any of the low-end ethernet drivers yet, though... -Toke _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
