netdev - Re: Kernel 4.19 network performance - forwarding/routing normal users traffic

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Date:   Fri, 9 Nov 2018 10:56:30 +0100
From:   Paweł Staszewski <pstaszewski@...are.pl>
To:     Saeed Mahameed <saeedm@...lanox.com>,
        "dsahern@...il.com" <dsahern@...il.com>,
        "brouer@...hat.com" <brouer@...hat.com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "yoel@...knet.dk" <yoel@...knet.dk>
Subject: Re: Kernel 4.19 network performance - forwarding/routing normal users
 traffic



W dniu 09.11.2018 o 05:52, Saeed Mahameed pisze:
> On Thu, 2018-11-08 at 17:42 -0700, David Ahern wrote:
>> On 11/8/18 5:40 PM, Paweł Staszewski wrote:
>>> W dniu 08.11.2018 o 17:32, David Ahern pisze:
>>>> On 11/8/18 9:27 AM, Paweł Staszewski wrote:
>>>>>>> What hardware is this?
>>>>>>>
>>>>> mellanox connectx 4
>>>>> ethtool -i enp175s0f0
>>>>> driver: mlx5_core
>>>>> version: 5.0-0
>>>>> firmware-version: 12.21.1000 (SM_2001000001033)
>>>>> expansion-rom-version:
>>>>> bus-info: 0000:af:00.0
>>>>> supports-statistics: yes
>>>>> supports-test: yes
>>>>> supports-eeprom-access: no
>>>>> supports-register-dump: no
>>>>> supports-priv-flags: yes
>>>>>
>>>>> ethtool -i enp175s0f1
>>>>> driver: mlx5_core
>>>>> version: 5.0-0
>>>>> firmware-version: 12.21.1000 (SM_2001000001033)
>>>>> expansion-rom-version:
>>>>> bus-info: 0000:af:00.1
>>>>> supports-statistics: yes
>>>>> supports-test: yes
>>>>> supports-eeprom-access: no
>>>>> supports-register-dump: no
>>>>> supports-priv-flags: yes
>>>>>
>>>>>>> Start with:
>>>>>>>
>>>>>>> echo 1 > /sys/kernel/debug/tracing/events/xdp/enable
>>>>>>> cat /sys/kernel/debug/tracing/trace_pipe
>>>>>>    cat /sys/kernel/debug/tracing/trace_pipe
>>>>>>            <idle>-0     [045] ..s. 68469.467752:
>>>>>> xdp_devmap_xmit:
>>>>>> ndo_xdp_xmit map_id=32 map_index=5 action=REDIRECT sent=0
>>>>>> drops=1
>>>>>> from_ifindex=4 to_ifindex=5 err=-6
>>>> FIB lookup is good, the redirect is happening, but the mlx5
>>>> driver does
>>>> not like it.
>>>>
>>>> I think the -6 is coming from the mlx5 driver and the packet is
>>>> getting
>>>> dropped. Perhaps this check in mlx5e_xdp_xmit:
>>>>
>>>>          if (unlikely(sq_num >= priv->channels.num))
>>>>                   return -ENXIO;
>>> I removed that part and recompiled - but after running now xdp_fwd
>>> i
>>> have kernel pamic :)
> hh, no please don't do such thing :)
yes - dirty "try" :)
Code back in place :)


>
> It must be because the tx netdev has less tx queues than the rx netdev.
> or the rx netdev rings are bound to a high cpu indexes.
>
> anyway, best practice is to open #cores RX/TX netdev on both sides
>
> ethtool -L enp175s0f0  combined $(nproc)
> ethtool -L enp175s0f1  combined $(nproc)
Ok now it is working.

Time for some tests :)

Thanks

>> Jesper or one of the Mellanox folks needs to respond about the config
>> needed to run XDP with this NIC. I don't have a 40G or 100G card to
>> play
>> with.
>