On Thu, Oct 6, 2022 at 1:01 AM Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote: > > On Wed, Oct 05, 2022 at 01:11:34AM +0200, Daniel Borkmann wrote: > > I cannot help but feel that prio logic copy-paste from old tc, netfilter and friends > is done because "that's how things were done in the past". > imo it was a well intentioned mistake and all networking things (tc, netfilter, etc) > copy-pasted that cumbersome and hard to use concept. > Let's throw away that baggage? > In good set of cases the bpf prog inserter cares whether the prog is first or not. > Since the first prog returning anything but TC_NEXT will be final. > I think prog insertion flags: 'I want to run first' vs 'I don't care about order' > is good enough in practice. Any complex scheme should probably be programmable > as any policy should. For example in Meta we have 'xdp chainer' logic that is similar > to libxdp chaining, but we added a feature that allows a prog to jump over another > prog and continue the chain. Priority concept cannot express that. > Since we'd have to add some "policy program" anyway for use cases like this > let's keep things as simple as possible? > Then maybe we can adopt this "as-simple-as-possible" to XDP hooks ? > And allow bpf progs chaining in the kernel with "run_me_first" vs "run_me_anywhere" > in both tcx and xdp ? You just described the features already offered by tc opcodes + priority. This problem is solvable by some user space resource arbitration scheme. Reading through the thread - a daemon of some sort will do. A daemon which issues tokens that can be validated in the kernel (kerberos type of approach) would be the best i.e fds alone dont resolve this. cheers, jamal
