Hi Jonathan, Sorry I don't have good suggestions but I have a couple of questions.
On Fri, Mar 29, 2019 at 9:17 AM Jonathan Lemon <b...@fb.com> wrote: > > Background: > > With AF_XDP, packets are placed on queues which are serviced directly from > an application running in user space, which promises greatly increased > performance. However, not all incoming packets should be delivered to the > application; there may be management traffic, or packets which should be > handled by normal Linux networking applications. I thought we can put a XDP program to filter for AF_XDP. So pass the management traffic to normal linux networking stack, and other traffic to AF_XDP socket. Does this help? > > Having the AF_XDP application handle the packets and return them to the > kernel for processing is not ideal, nor is adding a bpf filter at the kernel > level which performs the redirection. It would be nicer if the redirection > was done in the NIC itself. Fortunately, there is a facility for this: the > RX network flow classification. > May I know your use case for packets handled in AF_XDP, and then return/re-inject to kernel? Our case is that when packets received from AF_XDP netdev, we want to forward to a vm (tun/tap) or container (veth), so have to reinject to kernel. Regards, William > Unfortunately, the target of the classification is currently a single queue. > > Traffic arriving at a NIC which is not steered to a specific queue can be > distributed across a set of queues through the RX flow hash redirection > table (RSS steering). But being able to target a separate RSS object would > allow arbitrary distribution of previously classified traffic. > > Ask: > > It would be nice to have more than one RSS table, which would be the target > of a classifier or default packet stream. > > Queues would be attached to an RSS object, and flow classifiers could target > the RSS object for further distribution. For example, something like: > > ethtool -X eth0 rss 0 queue 0-13 > ethtool -X eth0 rss 1 queue 14-55 > ethtool -N eth0 flow-type udp6 dst-port 4242 rss 1 > > This would set up a default RSS object (rss 0), which sprays traffic to 14 > queues; this would be equivalent to "ethtool -X eth0 equal 14". At the same > time, a second object (rss 1) is set up, distributing traffic across another > set of queues. > > Is there interest in adding this type of feature? Having the ability to > express this concept (not necessarily in ethtool) should facilitate having > HW vendors add this to their products. I believe that some vendors have > hardware which may be capable of this already. > -- > Jonathan
