Major changes in v2:
- The old $SECONDS variable is dropped from journalctl. Which allows:
- ... dropping the very short-lived COOLDOWN proposed in version 1.
- A new, optional NDTEST_LOG_DBG code which allows "stress testing"
the approach and proving that it is safe.
I tested and compared for many hours $SECONDS versus the NDTEST_START
approach that Alison submitted a few months ago and the conclusion is
very clear:
- $SECONDS does require a ~1.2 cool down between every test. As it was
done in v1.
- NDTEST_START requires zero cool down.
So that is why I dropped $SECONDS and the cool down.
> Split them into a patchset for easier review and then I'll take a
> look. Thanks!
There are 3 logical changes in the main commit:
A1) Dropping $SECONDS, replaced with NDTEST_START
A2) The new NDTEST_LOG_DBG which was/is critical for:
- proving that $SECONDS required a "cool down" (with version 1)
- proving NDTEST_START does _not_ require any cool down, safe
even without any.
B) The new, _harden_ journalctl check in check_dmesg() and its
kmsg_fail_if_missing and kmsg_no_fail_on. The main feature!
- B) requires A1) because $SECONDS is too imprecise. With B) only, the
tests fail.
- The A2) test code achieves nothing without B), it cannot prove
anything without B).
- A1) and A2) are logically independent but their code are fairly
intertwined and very painful to separate. Plus, B) would have to sit
in the middle: A1->B->A2
Long story short:
- while they could be logically separate, these changes are tightly
coupled with each other.
- breaking down that (relatively small) commit is theoretically
possible but would be very labor intensive. I know because I just went
through a similar "git action" to compare $SECONDS versus
NDTEST_START for COOLDOWN reasons and it was not fun at all.
