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

["Alice Mikityanska" <alice.kernel@fastmail.im>]

On Sat, Aug 15, 2026, at 02:07, Matthieu Baerts wrote:
> 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:

Thanks for the suggestion! I'll switch to KSFT_MACHINE_SLOW.

> 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.