From: Martin KaFai Lau <martin.lau@linux.dev>
To: Kui-Feng Lee <sinquersw@gmail.com>, Stanislav Fomichev <sdf@fomichev.me>
Cc: Kui-Feng Lee <thinker.li@gmail.com>,
bpf@vger.kernel.org, ast@kernel.org, song@kernel.org,
kernel-team@meta.com, andrii@kernel.org, kuifeng@meta.com
Subject: Re: [PATCH bpf-next 0/4] monitor network traffic for flaky test cases
Date: Mon, 15 Jul 2024 16:56:15 -0700 [thread overview]
Message-ID: <940fff33-ed2b-41e0-bac6-d388deda9446@linux.dev> (raw)
In-Reply-To: <4c658385-dc3c-46ff-a868-0159edf84dc1@gmail.com>
On 7/15/24 3:07 PM, Kui-Feng Lee wrote:
>
>
> On 7/15/24 14:33, Stanislav Fomichev wrote:
>> On 07/12, Kui-Feng Lee wrote:
>>> Run tcpdump in the background for flaky test cases related to network
>>> features.
>>
>> Have you considered linking against libpcap instead of shelling out
>> to tcpdump? As long as we have this lib installed on the runners
>> (likely?) that should be a bit cleaner than doing tcpdump.. WDYT?
>
> I just checked the script building the root image for vmtest. [1]
> It doesn't install libpcap.
>
> If our approach is to capture the packets in a file, and let developers
> download the file, it would be a simple and straight forward solution.
> If we want a log in text, it would be more complicated to parse
> packets.
>
> Martin & Stanislay,
>
> WDYT about capture packets in a file and using libpcap directly?
> Developers can download the file and parse it with tcpdump locally.
thinking out loud...
Re: libpcap (instead of tcpdump) part. I am not very experienced in libpcap. I
don't have a strong preference. I do hope patch 1 could be more straight forward
that no need to use loops and artificial udp packets to ensure the tcpdump is
fully ready to capture. I assume using libpcap can make this sync part
easier/cleaner (pthread_cond?) and not too much code is needed to use libpcap?
Re: dump to file and download by developer. If I read patch 1 correctly, it only
dumps everything at the end of the test (by calling traffic_monitor_report).
imo, it lost the chronological ordering with other ASSERT_* logs and does not
make a big difference (vs downloading as a file).
The developer needs to go through another exercise to figure out (e.g.) a
captured packet may be related to a ASSERT_* failure by connecting the timestamp
between the ASSERT_* log and the captured packet (afaik, there is a timestamp in
the CI raw log). Ideally, the packet can be logged to stderr/out as soon as it
is captured such that the developer can still sort of relate the packet with the
other ASSERT_*() log around it.
next prev parent reply other threads:[~2024-07-15 23:56 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-13 5:55 [PATCH bpf-next 0/4] monitor network traffic for flaky test cases Kui-Feng Lee
2024-07-13 5:55 ` [PATCH bpf-next 1/4] selftests/bpf: Add traffic monitor functions Kui-Feng Lee
2024-07-14 0:18 ` Kui-Feng Lee
2024-07-14 15:27 ` kernel test robot
2024-07-13 5:55 ` [PATCH bpf-next 2/4] selftests/bpf: Monitor traffic for tc_redirect/tc_redirect_dtime Kui-Feng Lee
2024-07-13 5:55 ` [PATCH bpf-next 3/4] selftests/bpf: Monitor traffic for sockmap_listen Kui-Feng Lee
2024-07-13 5:55 ` [PATCH bpf-next 4/4] selftests/bpf: Monitor traffic for select_reuseport Kui-Feng Lee
2024-07-13 19:29 ` [PATCH bpf-next 0/4] monitor network traffic for flaky test cases Kui-Feng Lee
2024-07-15 21:33 ` Stanislav Fomichev
2024-07-15 22:07 ` Kui-Feng Lee
2024-07-15 23:56 ` Martin KaFai Lau [this message]
2024-07-16 0:57 ` Kui-Feng Lee
2024-07-16 3:25 ` Stanislav Fomichev
2024-07-16 6:46 ` Kui-Feng Lee
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