Re: [PATCH net-next 2/4] selftests: net: Lower threshold on debug kernels for big_tcp_tunnels.sh

[Matthieu Baerts <matttbe@kernel.org>]

Hi Alice,

On 14/08/2026 21:41, Alice Mikityanska wrote:
> From: Alice Mikityanska <alice@isovalent.com>
> 
> CONFIG_DEBUG_NET kernels run slower and generate fewer BIG TCP packets,
> making the test flaky on upstream CI runners. Lower the default
> threshold for those kernels.

Thank you for looking at that!

> Signed-off-by: Alice Mikityanska <alice@isovalent.com>
> ---
>  tools/testing/selftests/net/big_tcp_tunnels.sh | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/big_tcp_tunnels.sh b/tools/testing/selftests/net/big_tcp_tunnels.sh
> index 9b7d0456bcc1..e27774eae20e 100755
> --- a/tools/testing/selftests/net/big_tcp_tunnels.sh
> +++ b/tools/testing/selftests/net/big_tcp_tunnels.sh
> @@ -17,11 +17,25 @@ CLIENT_IP6="2001:db8::1:2"
>  CLIENT_IP4_TUN="192.168.2.2"
>  CLIENT_IP6_TUN="2001:db8::2:2"
>  
> -: "${PACKETS_THRESHOLD:=1000}"
> -
>  # Kselftest framework requirement - SKIP code is 4.
>  ksft_skip=4
>  
> +is_debug() {
> +	local config="/proc/config.gz"
> +	[ -f "$config" ] || config="/boot/config-$(uname -r)"
> +	[ -f "$config" ] || return 1 # No config found; assume non-debug.
> +	gzip -dcfq "$config" | grep -qx 'CONFIG_DEBUG_NET=y' || return 1

Are you sure it is CONFIG_DEBUG_NET that causes that? It shouldn't be
that heavy.

Do you not want to change the thresholds only for the -dbg runners using
kernel/configs/debug.config? If yes, you should check if
KSFT_MACHINE_SLOW == yes:

https://github.com/linux-netdev/nipa/wiki/How-to-run-netdev-selftests-CI-style#dealing-with-slow-runners-in-performancelatency-tests

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