Re: [PATCH net-next v2 0/3] selftests/net: packetdrill: netns and two imports

Willem de Bruijn
2024-09-12T12:10:05Z

Matthieu Baerts wrote:
> Hi Willem,
>
> On 12/09/2024 02:52, Willem de Bruijn wrote:
> > From: Willem de Bruijn <willemb@google.com>
> >
> > 1/3: run in nets, as discussed, and add missing CONFIGs
> > 2/3: import tcp/zerocopy
> > 3/3: import tcp/slow_start
>
> Thank you for the v2. This new version looks good to me:
>
> Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
>
>
> I didn't pay too much attention to the new tests, because they look
> good, heavily tested I suppose, and I guess the goal is not to diverge
> from the original ones for the moment. Still, please note that the CI
> reported some timing issues with tcp_zerocopy_closed.pkt when using a
> debug kernel config, e.g.
>
> > tcp_zerocopy_closed.pkt:22: timing error: expected system call return at 0.100596 sec but happened at 0.109564 sec; tolerance 0.004000 sec
>
> https://netdev.bots.linux.dev/contest.html?executor=vmksft-packetdrill-dbg&test=tcp-zerocopy-closed-pkt

Thanks Matthieu. I did not run the dbg variant often enough to observe
that. Note to self to run more times before I submit.

It seems to fail 2/10 times on the dbg spinner. I don't have an
explanation for the failure yet. The line itself has no expected delay

# script packet: 0.113203 S 0:0(0) <mss 1460,sackOK,TS val 0 ecr 0,nop,wscale 8>
# actual packet: 0.107191 S 0:0(0) win 65535 <mss 1460,sackOK,TS val 0 ecr 0,nop,wscale 8>

+0.1 recvmsg(4, {msg_name(...)=...,
msg_iov(1)=[{...,0}],
msg_flags=MSG_ERRQUEUE,
msg_control=[]}, MSG_ERRQUEUE) = -1 EAGAIN (Resource temporarily unavailable)

+0...0 connect(4, ..., ...) = 0

+0 > S 0:0(0) <mss 1460,sackOK,TS val 0 ecr 0,nop,wscale 8>

I guess the expectation includes the +0.1 delay before calling recvmsg, and that
timer fired a bit early.

I previously shared a draft patch to adjust --tolerance_usecs in dbg runs.
May have to send that after all.