I am submitting a new selftest for the netpoll subsystem specifically
targeting the case where the RX is polling in the TX path, which is
a case that we don't have any test in the tree today. This is done when
netpoll_poll_dev() called, and this test creates a scenario when that is
probably.
The test does the following:
1) Configuring a single RX/TX queue to increase contention on the
interface.
2) Generating background traffic to saturate the network, mimicking
real-world congestion.
3) Sending netconsole messages to trigger netpoll polling and monitor
its behavior.
4) Using dynamic netconsole targets via configfs, with the ability to
delete and recreate targets during the test.
5) Running bpftrace in parallel to verify that netpoll_poll_dev() is
called when expected. If it is called, then the test passes,
otherwise the test is marked as skipped.
In order to achieve it, I stole Jakub's bpftrace helper from [1], and
did some small changes that I found useful to use the helper.
So, this patchset basically contains:
1) The code stolen from Jakub
2) Improvements on bpftrace() helper
3) The selftest itself
Link: https://lore.kernel.org/all/20250421222827.283737-22-kuba@xxxxxxxxxx/ [1]
---
Changes in v3:
- Make pylint happy (Simon)
- Remove the unnecessary patch in bpftrace to raise an exception when it
fails. (Jakub)
- Improved the bpftrace code (Willem)
- Stop sending messages if bpftrace is not alive anymore.
- Link to v2: https://lore.kernel.org/r/20250625-netpoll_test-v2-0-47d27775222c@xxxxxxxxxx
Changes in v2:
- Stole Jakub's helper to run bpftrace
- Removed the DEBUG option and moved logs to logging
- Change the code to have a higher chance of calling netpoll_poll_dev().
In my current configuration, it is hitting multiple times during the
test.
- Save and restore TX/RX queue size (Jakub)
- Link to v1: https://lore.kernel.org/r/20250620-netpoll_test-v1-1-5068832f72fc@xxxxxxxxxx
---
Breno Leitao (2):
selftests: drv-net: Strip '@' prefix from bpftrace map keys
selftests: net: add netpoll basic functionality test
Jakub Kicinski (1):
selftests: drv-net: add helper/wrapper for bpftrace
tools/testing/selftests/drivers/net/Makefile | 1 +
.../selftests/drivers/net/lib/py/__init__.py | 3 +-
.../testing/selftests/drivers/net/netpoll_basic.py | 345 +++++++++++++++++++++
tools/testing/selftests/net/lib/py/utils.py | 35 +++
4 files changed, 383 insertions(+), 1 deletion(-)
---
base-commit: 8efa26fcbf8a7f783fd1ce7dd2a409e9b7758df0
change-id: 20250612-netpoll_test-a1324d2057c8
Best regards,
--
Breno Leitao <leitao@xxxxxxxxxx>
