[Bloat] Router congestion, slow ping/ack times with kernel 5.4.60

[Thomas Rosenstein]

On 12 Nov 2020, at 16:42, Jesper Dangaard Brouer wrote:

> On Thu, 12 Nov 2020 14:42:59 +0100
> "Thomas Rosenstein" <thomas.rosenstein at creamfinance.com> wrote:
>
>>> Notice "Adaptive" setting is on.  My long-shot theory(2) is that 
>>> this
>>> adaptive algorithm in the driver code can guess wrong (due to not
>>> taking TSO into account) and cause issues for
>>>
>>> Try to turn this adaptive algorithm off:
>>>
>>>   ethtool -C eth4 adaptive-rx off adaptive-tx off
>>>
> [...]
>>>>
>>>> rx-usecs: 32
>>>
>>> When you run off "adaptive-rx" you will get 31250 interrupts/sec
>>> (calc 1/(32/10^6) = 31250).
>>>
>>>> rx-frames: 64
> [...]
>>>> tx-usecs-irq: 0
>>>> tx-frames-irq: 0
>>>>
>>> [...]
>>
>> I have now updated the settings to:
>>
>> ethtool -c eth4
>> Coalesce parameters for eth4:
>> Adaptive RX: off  TX: off
>> stats-block-usecs: 0
>> sample-interval: 0
>> pkt-rate-low: 0
>> pkt-rate-high: 0
>>
>> rx-usecs: 0
>
> Please put a value in rx-usecs, like 20 or 10.
> The value 0 is often used to signal driver to do adaptive.

Ok, put it now to 10.

Goes a bit quicker (transfer up to 26 MB/s), but discards and pci stalls 
are still there.

Ping times are noticable improved:

64 bytes from x.x.x.x: icmp_seq=39 ttl=64 time=0.172 ms
64 bytes from x.x.x.x: icmp_seq=40 ttl=64 time=0.414 ms
64 bytes from x.x.x.x: icmp_seq=41 ttl=64 time=0.183 ms
64 bytes from x.x.x.x: icmp_seq=42 ttl=64 time=1.41 ms
64 bytes from x.x.x.x: icmp_seq=43 ttl=64 time=0.172 ms
64 bytes from x.x.x.x: icmp_seq=44 ttl=64 time=0.228 ms
64 bytes from x.x.x.x: icmp_seq=46 ttl=64 time=0.120 ms
64 bytes from x.x.x.x: icmp_seq=47 ttl=64 time=1.47 ms
64 bytes from x.x.x.x: icmp_seq=48 ttl=64 time=0.162 ms
64 bytes from x.x.x.x: icmp_seq=49 ttl=64 time=0.160 ms
64 bytes from x.x.x.x: icmp_seq=50 ttl=64 time=0.158 ms
64 bytes from x.x.x.x: icmp_seq=51 ttl=64 time=0.113 ms

>
>> rx-frames: 32
>> rx-usecs-irq: 0
>> rx-frames-irq: 0
>
>
>
> -- 
> Best regards,
>   Jesper Dangaard Brouer
>   MSc.CS, Principal Kernel Engineer at Red Hat
>   LinkedIn: http://www.linkedin.com/in/brouer