[LTP] [RFC PATCH] tst_test: Add flags to control runtime scaling in timing sensitive tests

[Li Wang]

On Mon, Jun 23, 2025 at 7:43 PM Martin Doucha <mdoucha@suse.cz> wrote:

> On 23. 06. 25 11:12, Li Wang via ltp wrote:
> > Some tests, such as those using fuzzy synchronization or probabilistic
> triggers
> > (e.g. preadv203), require sufficient runtime to collect meaningful
> results.
> > These tests often rely on thresholds like `fzsync_pair.min_samples`,
> which must
> > be met during the runtime window.
> >
> > When LTP_RUNTIME_MUL is set to a value < 1.0 (commonly in CI
> environments),
> > tests may run for too short a time, failing to gather enough samples and
> > silently producing false negatives or unstable results.
> >
> > This patch introduces the following test flags in `enum tst_flag` to
> provide
> > fine-grained control over runtime and timeout scaling:
> >
> >    - TST_NO_RUNTIME_MUL:
> >        Ignore LTP_RUNTIME_MUL and use the original .runtime value.
> >
> >    - TST_NO_TIMEOUT_MUL:
> >        Ignore LTP_TIMEOUT_MUL and use the original .timeout value.
> >
> >    - TST_NO_FRACTIONAL_RUNTIME_MUL:
> >        If LTP_RUNTIME_MUL is less than 1.0, round it up to 1.0 to
> preserve
> >        intended test duration.
>
> I think it'd make more sense to define a minimal runtime in the LTP
> library (e.g. 1 second) and allow tests to override the value with
> tst_test.min_runtime. Then you can apply fractional LTP_RUNTIME_MUL
> safely to any test.
>

That has been achieved in
https://lists.linux.it/pipermail/ltp/2025-June/043960.html.
which avoids .runtime being rounded to zero with fractional LTP_RUNTIME_MUL.

This patch introduces TST_NO_FRACTIONAL_RUNTIME_MUL, mainly to
solve the problem that some special tests (e.g. fuzzy-lib, preadv203) should
not reduce the runtime during execution. Setting a minimum runtime (e.g. 1
second)
does not meet the requirements.



-- 
Regards,
Li Wang