netdev - Re: [PATCH net-next 2/2] selftests/net: integrate packetdrill with ksft

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Message-ID: <a49069e1-d90b-4edb-9a9a-3d63972c1c5f@redhat.com>
Date: Fri, 6 Sep 2024 09:24:38 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>,
 Jakub Kicinski <kuba@...nel.org>
Cc: netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
 ncardwell@...gle.com, shuah@...nel.org, linux-kselftest@...r.kernel.org,
 fw@...len.de, Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next 2/2] selftests/net: integrate packetdrill with
 ksft

On 9/6/24 03:31, Willem de Bruijn wrote:
> Willem de Bruijn wrote:
>> Willem de Bruijn wrote:
>>> Jakub Kicinski wrote:
>>>> On Wed,  4 Sep 2024 23:07:03 -0400 Willem de Bruijn wrote:
>>>>> +++ b/tools/testing/selftests/net/packetdrill/config
>>>>> @@ -0,0 +1 @@
>>>>> +CONFIG_TCP_MD5SIG=y
>>>>
>>>> Looks like this is not enough:
>>>>
>>>> # 1..2
>>>> # open tun device: No such file or directory
>>>> # not ok 1 ipv4
>>>> # open tun device: No such file or directory
>>>>
>>>> https://netdev-3.bots.linux.dev/vmksft-packetdrill/results/759141/1-tcp-inq-client-pkt/stdout
>>>>
>>>> Resulting config in the build:
>>>>
>>>> # CONFIG_TUN is not set
>>>>
>>>> https://netdev-3.bots.linux.dev/vmksft-packetdrill/results/759141/config
>>>>
>>>> Keep in mind the "Important" note here:
>>>>
>>>> https://github.com/linux-netdev/nipa/wiki/How-to-run-netdev-selftests-CI-style#how-to-build
>>>>
>>>> I recommend using a fresh tree or mrproper for testing vng configs.
>>>>
>>>> Feel free to post v2 without the 24h wait, it's a bit tricky to handle
>>>> new targets in CI, sooner we merge this the less manual work for me..
>>>
>>> Oops sorry. Thanks for the pointer.
>>>
>>> Sent a v2 with CONFIG_TUN and a few other CONFIGS from reviewing
>>> the existing configs and defaults.sh. The above steps work for me now.
>>
>> Packetdrill scripts are sensitive to timing.
>> On the dbg build, I just observe a flaky test.
>>
>> The tool takes --tolerance_usecs and --tolerance_percent arguments.
>> I may have to update ksft_runner.sh to increase one if a dbg build is
>> detected.
>>
>> Let me know if I should respin now. Else I can also follow-up.
>>
>> Need to figure out how best to detect debug builds. It is not in
>> uname, and no proc/config.gz. Existence of /sys/kernel/debug/kmemleak
>> is a proxy for current kernel/configs/debug.config, if a bit crude.
> 
> Should have kept on reading. Will use KSFT_MACHINE_SLOW:
> 
> +declare -a optargs
> +if [[ "${KSFT_MACHINE_SLOW}" == "yes" ]]; then
> +       optargs+=('--tolerance_usecs=10000')
> +fi
> +
>   ktap_print_header
>   ktap_set_plan 2

I'm sorry for the late reply. FWIW, for mptcp pktdrill tests on slow 
machines (VMs over cloud) we use tolerance=100000 - put we have to be 
careful WRT fast retransmissions and timing in the script themself.

Cheers,

Paolo