Re: [PATCH net-next] selftests: drv-net: add BIG TCP test cases

On Fri, Sep 11, 2026 at 10:01:01AM -0700, Jakub Kicinski wrote:

On Thu, 10 Sep 2026 22:06:59 -0700 Narcisa Vasile wrote:

quoted

Add four new test cases that validate coalescing
under increased size limits (BIG TCP):

Looks like SW is struggling to aggregate enough. Do we need longer
timeouts perhaps? Note that the debug kernel build includes 
kernel/configs/debug.config

AI says:

Thanks for adding the BIG TCP coalescing coverage to gro_sw.py. CI is
flagging the new subtests as failing on our debug-kernel executor
(vmksft-net-drv-dbg, gro-sw-py):

  not ok gro_sw.test.ipv4_big_tcp_data_same
  not ok gro_sw.test.ipv4_big_tcp_data_lrg_sml
  not ok gro_sw.test.ipv4_big_tcp_tcp_seq
  not ok gro_sw.test.ipv4_big_tcp_large_max
  (and the ipv6 equivalents)

The rx side never fully coalesces the injected segments before the
background receiver gives up and the test's retry loop (6 attempts) is
exhausted, e.g.:

  Expected {68952 }, Total 1 packets
  Received {20280 [!=68952]40560 [!=0]8112 [!=0]}, Total 3 packets.

I've run the tests in a loop on a slower system running a debug kernel using
10x the previous flush timeout and I still noticed retries every 10-20
iterations, so I've settled on 15x higher timeout to account for variability
across different systems.

1..4
ok 1 gro_sw.test.ipv4_big_tcp_data_same
ok 2 gro_sw.test.ipv4_big_tcp_data_lrg_sml
ok 3 gro_sw.test.ipv4_big_tcp_tcp_seq
ok 4 gro_sw.test.ipv4_big_tcp_large_max
# Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0

1..4
ok 1 gro_sw.test.ipv6_big_tcp_data_same
ok 2 gro_sw.test.ipv6_big_tcp_data_lrg_sml
ok 3 gro_sw.test.ipv6_big_tcp_tcp_seq
ok 4 gro_sw.test.ipv6_big_tcp_large_max
# Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0