Björn Töpel <bjorn.topel@xxxxxxxxx> writes: > On Mon, 25 Nov 2019 at 12:18, Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote: >> >> Björn Töpel <bjorn.topel@xxxxxxxxx> writes: >> >> > From: Björn Töpel <bjorn.topel@xxxxxxxxx> >> > >> > The xdp_call.h header wraps a more user-friendly API around the BPF >> > dispatcher. A user adds a trampoline/XDP caller using the >> > DEFINE_XDP_CALL macro, and updates the BPF dispatcher via >> > xdp_call_update(). The actual dispatch is done via xdp_call(). >> > >> > Note that xdp_call() is only supported for builtin drivers. Module >> > builds will fallback to bpf_prog_run_xdp(). >> >> I don't like this restriction. Distro kernels are not likely to start >> shipping all the network drivers builtin, so they won't benefit from the >> performance benefits from this dispatcher. >> >> What is the reason these dispatcher blocks have to reside in the driver? >> Couldn't we just allocate one system-wide, and then simply change >> bpf_prog_run_xdp() to make use of it transparently (from the driver >> PoV)? That would also remove the need to modify every driver... >> > > Good idea! I'll try that out. Thanks for the suggestion! Awesome! I guess the table may need to be a bit bigger if it's system-wide? But since you've already gone to all that trouble with the binary search, I guess that shouldn't have too much of a performance impact? Maybe the size could even be a config option so users/distros can make their own size tradeoff? -Toke
