Re: [PATCH bpf-next v7 1/3] bpf: Add "live packet" mode for XDP in bpf_prog_run()

On Wed, Jan 12, 2022 at 05:37:54PM -0800, Alexei Starovoitov wrote:

On Sun, Jan 9, 2022 at 4:30 AM Toke Høiland-Jørgensen [off-list ref] wrote:

quoted

I left that out on purpose: I feel it's exposing an internal
implementation detail as UAPI (as you said). And I'm not convinced it
really needed (or helpful) - see below.

It's irrelevant whether it's documented or not.
Once this implementation detail is being relied upon
by user space it becomes an undocumented uapi that we cannot change.

quoted

I'll try implementing a TCP stream mode in xdp_trafficgen just to make
sure I'm not missing something. But I believe that sending out a stream
of packets that looks like a coherent TCP stream should be simple
enough, at least. Dealing with the full handshake + CWND control loop
will be harder, though, and right now I think it'll require multiple
trips back to userspace.

The patch set looks very close to being able to do such TCP streaming.
Let's make sure nothing is missing from API before we land it.

Hi Toke,  I am also looking at ways to blast tcp packets by using
bpf to overcome the pktgen udp-only limitation.
Are you planning to respin with a TCP stream mode in xdp_trafficgen ?
Thanks !