Re: Need help in interpreting ip status output

["André Hartmann" <aha_1980@gmx.de>]

Hi Oliver,

thanks for your answer. I hope you are well.

> Hi André,
>
> I have an idea ;-)
>
> On 12/03/2020 18.43, André Hartmann wrote:
>
>>> can someone help me interpreting the following ip output:
>>>
>>> ip -s link show can1
>>>       3: can1: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state
>>> UNKNOWN mode DEFAULT group default qlen 100
>>>           link/can
>>>           RX: bytes  packets  errors  dropped overrun mcast
>>>           0          9987413  1       74      1       0
>>>           TX: bytes  packets  errors  dropped carrier collsns
>>>           0          0        0       0       0       0
>>>
>>> I'm especially interested in the meaning of the
>>>
>>> * 1 errors
>>> * 74 dropped
>>> * 1 overrun
>
> E.g. if you look into
> linux/drivers/net/can/sja1000/sja1000.c
> you can see that an overrun error also triggers the error counter to
> increase - that's why both are set to 1.
>
> The reason for the overrun error is a notification from the CAN
> controller itself. It tells us that the received CAN frame has not been
> read from the controller until the next CAN frame arrived.

Ok, that's what I thought too, thanks for the confirmation.

> The dropped counter usually indicates that the CAN driver did not get a
> skbuff data structure (e.g. out of memory condition).
>
> This is NOT good. What CAN hardware/setup are you using?

Actually it's not my system. The report is from a customer doing a full
load test on an iMX8: https://bugreports.qt.io/browse/QTBUG-82610

I guess the customer should try a more recent Kernel than 4.14 first?

Thanks, and best regards,
André

>
> Regards,
> Oliver