On Tue, Oct 26, 2021 at 4:08 AM Konrad Zemek <konrad@xxxxxxxx> wrote: > > On Monday, October 25th, 2021 at 8:26 PM, Jun Hu <hujun.work@xxxxxxxxx> wrote: > > > On Mon, Oct 25, 2021 at 3:48 AM Toke Høiland-Jørgensen toke@xxxxxxxxxx wrote: > > > > > Jun Hu hujun.work@xxxxxxxxx writes: > > > > > > > Hi, > > > > > > > > I want to put a timestamp in the egress packets, and I want to use > > > > > > > > AF_XDP socket for both sending and receiving packets; since a XDP > > > > > > > > kernel program only work in ingress direction, I wonder if I could use > > > > > > > > a tc kernel program to change a packet sent out via an AF_XDP socket? > > > > > > > > I searched around, but couldn't find any direct answer... > > > > > > Nope, AF_XDP bypasses the stack completely, so TC won't see the packet > > > > > > on egress... > > > > > > -Toke > > > > Ok, thanks for the clarification, I guess I have to wait for the XDP > > > > egress support ... > > You can also directly modify the packet that you send out through an AF_XDP socket, before putting it on the outgoing queue. Is there anything specific that you would want to do in an egress-attached BPF program that you would not be able to do in the userspace program that manages your AF_XDP socket? > > Konrad Yes, that's what I am doing right now, however ideally I want to add a timestamp to the packet as close as it egress the NIC; since AF_XDP doesn't have access to hardware timestamp, that's why I was searching for an alternative solution.
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