netdev - Re: [PATCH net-next] selftests/net: calibrate txtimestamp

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Date: Tue, 30 Jan 2024 17:47:36 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
 pabeni@...hat.com, linux-kselftest@...r.kernel.org, Willem de Bruijn
 <willemb@...gle.com>
Subject: Re: [PATCH net-next] selftests/net: calibrate txtimestamp

On Fri, 26 Jan 2024 21:31:51 -0500 Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@...gle.com>
> 
> The test sends packets and compares enqueue, transmit and Ack
> timestamps with expected values. It installs netem delays to increase
> latency between these points.
> 
> The test proves flaky in virtual environment (vng). Increase the
> delays to reduce variance. Scale measurement tolerance accordingly.
> 
> Time sensitive tests are difficult to calibrate. Increasing delays 10x
> also increases runtime 10x, for one. And it may still prove flaky at
> some rate.

Willem, do you still want us to apply this as is or should we do 
the 10x only if [ x$KSFT_MACHINE_SLOW != x ] ?