Re: [PATCH net-next 4/4] selftests: net: Fix slow configurations in big_tcp_tunnels.sh

Hi Alice,

On 14/08/2026 21:41, Alice Mikityanska wrote:

From: Alice Mikityanska <redacted>

The combination of checksum offload disabled (that causes software GSO)
and CONFIG_DEBUG_NET=y is inherently slow. Depending on the CPU power
and load, RTT may increase, limiting sk_pacing_rate, so tcp_tso_autosize
caps SKBs at around 40 segments, and zero BIG TCP packets are produced.

Increase sysctl net.ipv4.tcp_min_tso_segs and set a bigger initial value
of CWND in these configurations to force BIG TCP.

Just an innocent question: would it affect the test somehow if the
sysctl and initial cwnd is always modified, not just for a specific config?

(Note that apart from looking at ${KSFT_MACHINE_SLOW} in patch 2, I
think the series looks good to me, and can probably be sent to net after
the merge with net-next.)

Cheers,
Matt