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

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Message-ID: <Zuhhe4-MQHd3EkfN@mini-arch>
Date: Mon, 16 Sep 2024 09:48:59 -0700
From: Stanislav Fomichev <stfomichev@...il.com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: Matthieu Baerts <matttbe@...nel.org>, netdev@...r.kernel.org,
	davem@...emloft.net, kuba@...nel.org, edumazet@...gle.com,
	pabeni@...hat.com, ncardwell@...gle.com, shuah@...nel.org,
	linux-kselftest@...r.kernel.org,
	Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next v2 0/3] selftests/net: packetdrill: netns and
 two imports

On 09/12, Willem de Bruijn wrote:
> Matthieu Baerts wrote:
> > Hi Willem,
> > 
> > On 12/09/2024 02:52, Willem de Bruijn wrote:
> > > From: Willem de Bruijn <willemb@...gle.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@...nel.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.
> 
> https://lore.kernel.org/netdev/66da5b8b27259_27bb41294c@willemb.c.googlers.com.notmuch/

Not sure you've seen, but tcp_slow_start_slow-start-after-win-update.pkt
also just popped up on the dashboard for dbg:

# tcp_slow_start_slow-start-after-win-update.pkt:39: error handling packet: timing error: expected outbound packet in relative time range +0.600000~+0.620000

https://netdev-3.bots.linux.dev/vmksft-packetdrill-dbg/results/774981/1-tcp-slow-start-slow-start-after-win-update-pkt/stdout

Do we want to follow up with that '--tolerance_usecs=10000' you've
mentioned above?