netdev - Re: [PATCH net] selftests/net: packetdrill: increase timing tolerance in debug mode

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Message-ID: <0849977a-e772-4778-9130-c8ac0539bbdc@kernel.org>
Date: Fri, 20 Sep 2024 00:03:11 +0200
From: Matthieu Baerts <matttbe@...nel.org>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>, netdev@...r.kernel.org
Cc: davem@...emloft.net, kuba@...nel.org, edumazet@...gle.com,
 pabeni@...hat.com, sdf@...ichev.me, linux-kselftest@...r.kernel.org,
 Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net] selftests/net: packetdrill: increase timing tolerance
 in debug mode

Hi Willem,

On 19/09/2024 14:43, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@...gle.com>
> 
> Some packetdrill tests are flaky in debug mode. As discussed, increase
> tolerance.

Thank you for the patch!

> We have been doing this for debug builds outside ksft too.
> 
> Previous setting was 10000. A manual 50 runs in virtme-ng showed two
> failures that needed 12000. To be on the safe side, Increase to 14000.

So far (in 3 runs), it looks like 14000 is enough. But I guess it is
still a bit too early to conclude that.

https://netdev.bots.linux.dev/contest.html?executor=vmksft-packetdrill-dbg

(Your patch has been introduced in the net-next-2024-09-19--15-00 branch.)


Personally, I would not be chocked if the tolerance was even 10x higher
to cope with this very slow environment where we care less about timing
I think. But if less works, that's good:

Acked-by: Matthieu Baerts (NGI0) <matttbe@...nel.org>


Just one question for later: in the GitHub repo, some tests set the
tolerance in the .pkt file, will it be OK for these tests? I guess yes,
because the max they set is 10k, but I just want to double-check.


(Note that it is now easier to spot other errors :) e.g.)


https://netdev-3.bots.linux.dev/vmksft-packetdrill-dbg/results/779660/22-tcp-zerocopy-epoll-exclusive-pkt/stdout


Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.