On Thu, Jun 18, 2020 at 5:23 PM Jonathan Lemon <jonathan.lemon@xxxxxxxxx> wrote: > > On Sun, Jun 14, 2020 at 10:55:30AM +0200, Kal Cutter Conley wrote: > > Hi Saeed, > > Thanks for explaining the reasoning behind the special mlx5 queue > > numbering with XDP zerocopy. > > > > We have a process using AF_XDP that also shares the network interface > > with other processes on the system. ethtool rx flow classification > > rules are used to route the traffic to the appropriate XSK queue > > N..(2N-1). The issue is these queues are only valid as long they are > > active (as far as I can tell). This means if my AF_XDP process dies > > other processes no longer receive ingress traffic routed over queues > > N..(2N-1) even though my XDP program is still loaded and would happily > > always return XDP_PASS. Other drivers do not have this usability issue > > because they use queues that are always valid. Is there a simple > > workaround for this issue? It seems to me queues N..(2N-1) should > > simply map to 0..(N-1) when they are not active? > > If your XDP program returns XDP_PASS, the packet should be delivered to > the xsk socket. If the application isn't running, where would it go? XDP_PASS means the packet is passed to the normal network stack for processing. XDP_REDIRECT means the packet should be delivered to the xsk socket. > > I do agree that the usability of this can be improved. What if the flow > rules are inserted and removed along with queue creatioin/destruction? The problem is the mlx5 driver allows flow rules to be set on N..(2N-1) at any time; even when no XDP program is loaded. Given this fact, it would be totally weird if they just suddenly disappeared the first time the queues go inactive. That's why I suggested that they just always map to queues 0..(N-1) when they are not active. This way, at least it's less surprising. What do people think? > Jonathan Kal
|