Dave Taht <dave.t...@gmail.com> writes: > On Wed, Aug 1, 2018 at 10:25 AM Dave Taht <dave.t...@gmail.com> wrote: >> >> I wonder if ebpf has opcode space for an invsqrt? > > bpf_ktime_get_ns() exists... > > one thing that I don't know if bpf can do is read/write the > skb->tstamp field. The plan would be to rigorously write it (if not > supplied by hw) on all ingress ports and check it on all egress ports.
An XDP eBPF program (run at earliest possible ingress) has access to a buffer of arbitrary data that is attached to the skb and that can be read from later eBPF programs. So it doesn't need to muck with skb->tstamp for this. > That said, every time I've tried to do something in ebpf I hit a > limitation I'd not thunk of yet. Yeah, the whole XDP/eBPF system is somewhat of a work in progress ;) > For example, where can you attach the egress filter? > > My thought would be to use a bfifo > bpf -> bql, but from what little > I understand, it's bpf -> bfifo -> bql Yeah, it is. Don't think there's a way to run an eBPF program after the qdisc... -Toke _______________________________________________ Cake mailing list Cake@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/cake