2024-07-04 13:08 (UTC+0200), Mário Kuka: [...] > So I can't achieve my goal: traffic from the hairpin queues is not > dropped if the CPU queue is overloaded. > Any idea how to achieve this in example 4? > What is the problem, full packet buffers/memory in the device that are > shared between the hairpin and CPU queues? > > Any guidance or suggestions on how to achieve this would be greatly > appreciated.
So you want priority traffic to use a dedicated HW buffer pool. Good news: QoS is the mechanism to do it. Bad news: flow rules cannot be used to determine priority, so you need to mark packets with VLAN PCP or IPv4 DSCP. I've reproduced your results roughly with 60 Mpps @ PCP 0 (10 Mpps with MAC for hairpin, 50 Mpps with MAC for normal RxQ), then switched to 10 Mpps @ PCP 0 + 50 Mpps @ PCP 1 and this solved the issue (and so does 10 Mpps @ PCP 1 + 50 Mpps @ PCP 0). I expected the need to tune --buffer_size and --prio2buffer with mlnx_qos [1], but it appears to be unnecessary. No idea why this works and what buffer size is used for PCP 1. [1]: https://enterprise-support.nvidia.com/s/article/mlnx-qos
