RE: [PATCH bpf-next 0/8] Add support for transmitting packets using XDP in bpf_prog_run()

[John Fastabend <john.fastabend@gmail.com>]

Toke Høiland-Jørgensen wrote:
> This series adds support for transmitting packets using XDP in
> bpf_prog_run(), by enabling the xdp_do_redirect() callback so XDP programs
> can perform "real" redirects to devices or maps, using an opt-in flag when
> executing the program.
> 
> The primary use case for this is testing the redirect map types and the
> ndo_xdp_xmit driver operation without generating external traffic. But it
> turns out to also be useful for creating a programmable traffic generator.
> The last patch adds a sample traffic generator to bpf/samples, which
> can transmit up to 11.5 Mpps/core on my test machine.
> 
> To transmit the frames, the new mode instantiates a page_pool structure in
> bpf_prog_run() and initialises the pages with the data passed in by
> userspace. These pages can then be redirected using the normal redirection
> mechanism, and the existing page_pool code takes care of returning and
> recycling them. The setup is optimised for high performance with a high
> number of repetitions to support stress testing and the traffic generator
> use case; see patch 6 for details.
> 
> The series is structured as follows: Patches 1-2 adds a few features to
> page_pool that are needed for the usage in bpf_prog_run(). Similarly,
> patches 3-5 performs a couple of preparatory refactorings of the XDP
> redirect and memory management code. Patch 6 adds the support to
> bpf_prog_run() itself, patch 7 adds a selftest, and patch 8 adds the
> traffic generator example to samples/bpf.

Overall looks pretty good. Couple questions in the series though.

Thanks!
John