From: Jakub Kicinski <kuba@kernel.org>
To: Jason Xing <kerneljasonxing@gmail.com>
Cc: davem@davemloft.net, edumazet@google.com, pabeni@redhat.com,
horms@kernel.org, willemdebruijn.kernel@gmail.com,
netdev@vger.kernel.org
Subject: Re: [PATCH net-next] selftests: txtimestamp: ignore the old skb from ERRQUEUE
Date: Mon, 3 Mar 2025 07:41:05 -0800 [thread overview]
Message-ID: <20250303074105.0b562205@kernel.org> (raw)
In-Reply-To: <20250303080404.70042-1-kerneljasonxing@gmail.com>
On Mon, 3 Mar 2025 16:04:04 +0800 Jason Xing wrote:
> When I was playing with txtimestamp.c to see how kernel behaves,
> I saw the following error outputs if I adjusted the loopback mtu to
> 1500 and then ran './txtimestamp -4 -L 127.0.0.1 -l 30000 -t 100000':
>
> test SND
> USR: 1740877371 s 488712 us (seq=0, len=0)
> SND: 1740877371 s 489519 us (seq=29999, len=1106) (USR +806 us)
> USR: 1740877371 s 581251 us (seq=0, len=0)
> SND: 1740877371 s 581970 us (seq=59999, len=8346) (USR +719 us)
> USR: 1740877371 s 673855 us (seq=0, len=0)
> SND: 1740877371 s 674651 us (seq=89999, len=30000) (USR +795 us)
> USR: 1740877371 s 765715 us (seq=0, len=0)
> ERROR: key 89999, expected 119999
> ERROR: -12665 us expected between 0 and 100000
> SND: 1740877371 s 753050 us (seq=89999, len=1106) (USR +-12665 us)
> SND: 1740877371 s 800783 us (seq=119999, len=30000) (USR +35068 us)
> USR-SND: count=5, avg=4945 us, min=-12665 us, max=35068 us
>
> Actually, the kernel behaved correctly after I did the analysis. The
> second skb carrying 1106 payload was generated due to tail loss probe,
> leading to the wrong estimation of tskey in this C program.
>
> This patch does:
> - Neglect the old tskey skb received from ERRQUEUE.
> - Add a new test to count how many valid skbs received to compare with
> cfg_num_pkts.
This appears to break some UDP test cases when running in the CI:
https://netdev-3.bots.linux.dev/vmksft-net/results/16721/41-txtimestamp-sh/stdout
--
pw-bot: cr
next prev parent reply other threads:[~2025-03-03 15:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-03 8:04 [PATCH net-next] selftests: txtimestamp: ignore the old skb from ERRQUEUE Jason Xing
2025-03-03 14:07 ` Willem de Bruijn
2025-03-03 15:41 ` Jakub Kicinski [this message]
2025-03-03 16:31 ` Jason Xing
2025-03-03 16:49 ` Jason Xing
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