On Wed, 9 May 2018 20:34:26 -0700 David Ahern <dsah...@gmail.com> wrote:
> Provide a helper for doing a FIB and neighbor lookup in the kernel > tables from an XDP program. The helper provides a fastpath for forwarding > packets. If the packet is a local delivery or for any reason is not a > simple lookup and forward, the packet continues up the stack. > > If it is to be forwarded, the forwarding can be done directly if the > neighbor is already known. If the neighbor does not exist, the first > few packets go up the stack for neighbor resolution. Once resolved, the > xdp program provides the fast path. > > On successful lookup the nexthop dmac, current device smac and egress > device index are returned. > > The API supports IPv4, IPv6 and MPLS protocols, but only IPv4 and IPv6 > are implemented in this patch. The API includes layer 4 parameters if > the XDP program chooses to do deep packet inspection to allow compare > against ACLs implemented as FIB rules. > > Header rewrite is left to the XDP program. > > The lookup takes 2 flags: > - BPF_FIB_LOOKUP_DIRECT to do a lookup that bypasses FIB rules and goes > straight to the table associated with the device (expert setting for > those looking to maximize throughput) > > - BPF_FIB_LOOKUP_OUTPUT to do a lookup from the egress perspective. > Default is an ingress lookup. > > Initial performance numbers collected by Jesper, forwarded packets/sec: > > Full stack XDP FIB lookup XDP Direct lookup > IPv4 1,947,969 7,074,156 7,415,333 > IPv6 1,728,000 6,165,504 7,262,720 > The "Full stack" tests were with netfilter modules unloaded. Default setting with netfilter conntrack loaded and default Fedora firewall rules, show around 700Kpps. > These number are single CPU core forwarding on a Broadwell > E5-1650 v4 @ 3.60GHz. > > Signed-off-by: David Ahern <dsah...@gmail.com> Acked-by: Jesper Dangaard Brouer <bro...@redhat.com> This helper is awesome, as it really shows how XDP is meant to work in concert and cooperate with the existing network stack. -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer
