> On Jul 3, 2018, at 11:18 AM, Jonathan Morton <[email protected]> wrote: > >> On 3 Jul, 2018, at 1:23 am, Toke Høiland-Jørgensen <[email protected]> wrote: >> >> My hunch is that this has something to do with the way mlx5 uses multiple >> receive queues (and thus multiple CPUs). Which is probably different from >> veth... > > At this stage I'm pretty confident it has nothing to do with Cake, and > everything to do with the Mellanox hardware and driver. It does strike me > that Linux' default handling of multiqueue hardware doesn't map very well to > the qdisc interface.
That’s looking highly likely to me too. I’ll stop trying to repro this unless we come up with something new to try. I wonder if enabling the “lockless qdisc” support (https://lwn.net/Articles/698135/) we discussed late last year would change anything. It should work either way, even with a single qdisc lock, but just speculating, at those speeds with multiple cores competing for a single qdisc lock I wonder if we’re exposing a problem in the driver or somewhere else. _______________________________________________ Cake mailing list [email protected] https://lists.bufferbloat.net/listinfo/cake
