[Cake] the Cake stalemate

Toke Høiland-Jørgensen toke at toke.dk
Tue Jun 19 07:54:44 EDT 2018

Jonathan Morton <chromatix99 at gmail.com> writes:

>> On 19 Jun, 2018, at 12:55 pm, Toke Høiland-Jørgensen <toke at toke.dk> wrote:
>> Not sure there is a stalemate, actually. I just ran out of time to do
>> further revisions; planning to take that up again. Don't see any reason
>> why we shouldn't be able to succeed in getting Cake upstream in its
>> current form(ish) in just a few more revisions (or, who knows, maybe a
>> dozen more; better not jinx it ;)).
> My impression was that we were practically there - but we ran up
> against a hang bug which *may* have had a root cause elsewhere than
> Cake itself.  I strongly suspect we're tickling a HW driver bug, but
> we need someone with a different flavour of 100Gbps NIC to try (and
> hopefully fail) to reproduce it.

Yeah, that and getting the ACK filter approved by the TCP devs are the
major outstanding issues. I'm planning to go poke at the hanging issue
once I have some time, then hopefully fix whatever is causing it, and
resubmit :)

We also saw a bug on 32-bit MIPS where some combinations of 64-bit
netlink attributes would cause stats display in tc to fail. However, I
believe this is more a case of Cake exposing a latent bug somewhere in
the tc or kernel netlink code (alignment issues, perhaps?), and so I'm
not sure it is necessarily a blocker for merging Cake. However, if
someone could take a look that would be very helpful. I forget if the
current head of the cobalt branch exposes the bug, but I think it does.
It's quite obvious when it happens: no stats output whatsoever...


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