Re: [PATCH 1/2] selftests/kmod: increase the kmod timeout from 45 to 165

From: Shuah Khan
Date: Mon Mar 06 2023 - 11:12:20 EST


On 3/3/23 14:48, Luis Chamberlain wrote:
On Fri, Mar 03, 2023 at 01:35:10PM -0700, Shuah Khan wrote:
On 2/27/23 15:42, Luis Chamberlain wrote:
On Mon, Feb 27, 2023 at 03:32:50PM -0700, Shuah Khan wrote:
On 2/6/23 16:43, Luis Chamberlain wrote:
The default sefltests timeout is 45 seconds. If you run the kmod
selftests on your own with say:

./tools/testings/selftests/kmod.sh

Then the default timeout won't be in effect.

I've never ran kmod selftests using the generic make wrapper
(./tools/testing/selftests/run_kselftest.sh -s) util now
that I have support for it on kdevops [0]. And with that the
test is limitted to the default timeout which we quickly run
into. Bump this up to what I see is required on 8GiB / 8 vcpu
libvirt q35 guest as can be easily created now with kdevops.

To run selftests with kdevops:

make menuconfig # enable dedicated selftests and kmod test
make
make bringup
make linux
make selftests-kmod

This ends up taking about 280 seconds now, give or take add
50 seconds more more and we end up with 350. Document the
rationale.

[0] https://github.com/linux-kdevops/kdevops
Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
---
tools/testing/selftests/kmod/settings | 4 ++++
1 file changed, 4 insertions(+)
create mode 100644 tools/testing/selftests/kmod/settings

diff --git a/tools/testing/selftests/kmod/settings b/tools/testing/selftests/kmod/settings
new file mode 100644
index 000000000000..6fca0f1a4594
--- /dev/null
+++ b/tools/testing/selftests/kmod/settings
@@ -0,0 +1,4 @@
+# measured from a manual run:
+# time ./tools/testing/selftests/kmod/kmod.sh
+# Then add ~50 seconds more gracetime.
+timeout=350

Adding timeouts like this for individual tests increases the overall kselftest
run-time. I am not in favor of adding timeouts.

We have to find a better way to do this.

Well if folks don't have this the test will fail, and so a false
positive. If the goal is to have a low time timeout for "do not run
tests past this time and do not fail if we stopped the test" then
that seems to be likely one way to go and each test may need to be
modified to not fail fatally in case of a special signal.


We are finding more and more that timeout values are requiring
tweaks. I am in favor of coming up a way to exit the test with
a timeout condition.

OK so do we use the existing timeout as a "optional, I don't want my
test to take longer than this" or "if this test takes longer than
this amount this is a fatal issue"?

It isn't a fatal issue. So I wouldn't call it one. I would add a
message saying test timed out.

One way to handle this is:
- Add a test run-time option and have user tune it as needed.

Make the timeout an option so users can set it based on their
environments.


I ask because right now we can't override it even with an environment
variable. If we had such support we can let test runners (like kdevops)
use selftests with its own set of qualified / verified timeouts for the
VMs it uses.

For instance, Iw ant to soon start asking 0day to enable my kdevops
0-day tests for the subsystems I maintain, but I can't do that yet as
the timeout is not correct.

This test isn't part of the default run, so day has to run this as a
special case and it would make prefect sense to provide a tunable
timeout option.

thanks,
-- Shuah

Luis