Re: [PATCH bpf-next v11 2/5] selftests/bpf: Use random netns name for mptcp

On Tue, Aug 08, 2023 at 11:03:30PM -0700, Martin KaFai Lau wrote:

On 8/6/23 11:40 PM, Geliang Tang wrote:

quoted

On Fri, Aug 04, 2023 at 05:23:32PM -0700, Martin KaFai Lau wrote:

quoted

On 8/3/23 10:07 PM, Geliang Tang wrote:

quoted

Use rand() to generate a random netns name instead of using the fixed
name "mptcp_ns" for every test.

By doing that, we can re-launch the test even if there was an issue
removing the previous netns or if by accident, a netns with this generic
name already existed on the system.

Note that using a different name each will also help adding more
subtests in future commits.

Hi Martin,

I tried to run mptcp tests simultaneously, and got "Cannot create
namespace file "/var/run/netns/mptcp_ns": File exists" errors sometimes.
So I add this patch to fix it.

It's easy to reproduce, just run this commands in multiple terminals:
  > for i in `seq 1 100`; do sudo ./test_progs -t mptcp; done

Not only the "-t mptcp" test. Other tests in test_progs also don't support
running parallel in multiple terminals. Does it really help to test the bpf
part of the prog_tests/mptcp.c test by running like this? If it wants to
exercise the other mptcp networking specific code like this, a separate
mptcp test is needed outside of test_progs and it won't be run in the bpf
CI.

If you agree, can you please avoid introducing unnecessary randomness to the
test_progs where bpf CI and most users don't run in this way?

Thanks Martin. Sure, I agree. Let's drop this patch.

Also, please don't resend the patches too fast until the discussion is
concluded. Please give reasonable time for others to reply.

Sure. Please give me a clear reminder next time that it's time to resend
a new version of the patches.

I have a high level question. In LPC 2022
(https://lpc.events/event/16/contributions/1354/), I recall there was idea
in using bpf to make other mptcp decision/policy. Any thought and progress
on this? This set which only uses bpf to change the protocol feels like an
incomplete solution.

We are implementing MPTCP packet scheduler using BPF. Patches aren't
sent to BPF mail list yet, only temporarily on our mptcp repo[1].

Here are the patches:

 selftests/bpf: Add bpf_burst test
 selftests/bpf: Add bpf_burst scheduler
 bpf: Export more bpf_burst related functions
 selftests/bpf: Add bpf_red test
 selftests/bpf: Add bpf_red scheduler
 selftests/bpf: Add bpf_rr test
 selftests/bpf: Add bpf_rr scheduler
 selftests/bpf: Add bpf_bkup test
 selftests/bpf: Add bpf_bkup scheduler
 selftests/bpf: Add bpf_first test
 selftests/bpf: Add bpf_first scheduler
 selftests/bpf: Add bpf scheduler test
 selftests/bpf: add two mptcp netns helpers
 selftests/bpf: use random netns name for mptcp
 selftests/bpf: Add mptcp sched structs
 bpf: Add bpf_mptcp_sched_kfunc_set
 bpf: Add bpf_mptcp_sched_ops

If you could take a look at these patches in advance, I would greatly
appreciate it. Any feedback is welcome.

[1]
https://github.com/multipath-tcp/mptcp_net-next.git

-Geliang