[LTP] [PATCH v2] tst_test: Add min_runtime to control lower bound of scaled runtime
Martin Doucha
mdoucha@suse.cz
Mon Jun 23 16:42:50 CEST 2025
Hi!
On 23. 06. 25 16:02, Li Wang wrote:
> When LTP_RUNTIME_MUL is set to a value < 1.0 (commonly in CI or fast test
> modes), the effective runtime of tests may be scaled down too aggressively.
> For some tests especially those relying on probabilistic triggers or sampling
> (e.g., fuzzy sync, CVE stress loops, long fault injection), this can result in
> too few iterations or missed conditions, leading to unreliable results.
>
> This patch introduces a new field: .min_runtime;
>
> If set, this specifies the minimum allowed runtime (in seconds) after applying
> the LTP_RUNTIME_MUL scaling factor. The final runtime is calculated as:
>
> MAX(runtime * LTP_RUNTIME_MUL, min_runtime)
>
> If min_runtime is not set, a default minimum of 1 second is enforced.
>
> This approach replaces the need for special flags such as
> TST_NO_FRAC_RUNTIME_MUL and provides a more systematic, flexible solution.
>
> The following tests are updated to set .min_runtime:
> - preadv203
> - cve-2016-7117
> - tst_fuzzy_sync01
> - tst_fuzzy_sync02
>
> Suggested-by: Martin Doucha <mdoucha@suse.cz>
> Signed-off-by: Li Wang <liwang@redhat.com>
> Cc: Ian Wienand <iwienand@redhat.com>
> ---
>
> Notes:
> v1 --> v2:
> * replace the .flags by a new min_runtime filed
> * set 1 second as the default minimal runtime regardless
> LTP_RUNTIME_MUL value
>
> include/tst_test.h | 9 +++++++++
> lib/newlib_tests/tst_fuzzy_sync01.c | 2 +-
> lib/newlib_tests/tst_fuzzy_sync02.c | 2 +-
> lib/tst_test.c | 11 +++++++++--
> testcases/cve/cve-2016-7117.c | 2 +-
> testcases/kernel/syscalls/preadv2/preadv203.c | 2 +-
> 6 files changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/include/tst_test.h b/include/tst_test.h
> index 6fd8cbae3..9c21c1728 100644
> --- a/include/tst_test.h
> +++ b/include/tst_test.h
> @@ -460,6 +460,14 @@ struct tst_fs {
> * (e.g., TIMEOUT_MUL), ensuring consistent test duration across
> * different environments (e.g., debug vs. stock kernels).
> *
> + * @min_runtime: Optional lower bound (in seconds) applied after runtime is
> + * scaled by LTP_RUNTIME_MUL. If the scaled runtime is smaller
> + * than this value, it will be clamped up to min_runtime.
> + * This is useful for tests that require a minimum execution
> + * time to gather sufficient samples or trigger events (e.g.,
> + * probabilistic or fuzzy synchronization tests).
> + * If not set, a default minimum of 1 second is enforced.
> + *
> * @setup: Setup callback is called once at the start of the test in order to
> * prepare the test environment.
> *
> @@ -584,6 +592,7 @@ struct tst_fs {
>
> int timeout;
> int runtime;
> + int min_runtime;
>
> void (*setup)(void);
> void (*cleanup)(void);
> diff --git a/lib/newlib_tests/tst_fuzzy_sync01.c b/lib/newlib_tests/tst_fuzzy_sync01.c
> index b1390f460..16f30de57 100644
> --- a/lib/newlib_tests/tst_fuzzy_sync01.c
> +++ b/lib/newlib_tests/tst_fuzzy_sync01.c
> @@ -246,5 +246,5 @@ static struct tst_test test = {
> .test = run,
> .setup = setup,
> .cleanup = cleanup,
> - .runtime = 150,
> + .min_runtime = 150,
Lib tests don't need .min_runtime unless you specifically want to test
that LTP_RUNTIME_MUL gets handled correctly.
> };
> diff --git a/lib/newlib_tests/tst_fuzzy_sync02.c b/lib/newlib_tests/tst_fuzzy_sync02.c
> index bc079f6ff..3b0fb8a9b 100644
> --- a/lib/newlib_tests/tst_fuzzy_sync02.c
> +++ b/lib/newlib_tests/tst_fuzzy_sync02.c
> @@ -223,5 +223,5 @@ static struct tst_test test = {
> .test = run,
> .setup = setup,
> .cleanup = cleanup,
> - .runtime = 150,
> + .min_runtime = 150,
> };
> diff --git a/lib/tst_test.c b/lib/tst_test.c
> index 495e022f7..75a78be9a 100644
> --- a/lib/tst_test.c
> +++ b/lib/tst_test.c
> @@ -627,10 +627,14 @@ static void parse_mul(float *mul, const char *env_name, float min, float max)
> static int multiply_runtime(unsigned int runtime)
> {
> static float runtime_mul = -1;
> + int min_runtime = 1;
> +
> + if (tst_test->min_runtime)
> + min_runtime = MAX(1, tst_test->min_runtime);
>
> parse_mul(&runtime_mul, "LTP_RUNTIME_MUL", 0.0099, 100);
>
> - return runtime * runtime_mul;
> + return MAX(runtime * runtime_mul, min_runtime);
> }
>
> static struct option {
> @@ -662,7 +666,7 @@ static void print_help(void)
> fprintf(stderr, "LTP_SINGLE_FS_TYPE Specifies filesystem instead all supported (for .all_filesystems)\n");
> fprintf(stderr, "LTP_FORCE_SINGLE_FS_TYPE Testing only. The same as LTP_SINGLE_FS_TYPE but ignores test skiplist.\n");
> fprintf(stderr, "LTP_TIMEOUT_MUL Timeout multiplier (must be a number >=1)\n");
> - fprintf(stderr, "LTP_RUNTIME_MUL Runtime multiplier (must be a number >=1)\n");
> + fprintf(stderr, "LTP_RUNTIME_MUL Runtime multiplier (must be a number >0)\n");
> fprintf(stderr, "LTP_VIRT_OVERRIDE Overrides virtual machine detection (values: \"\"|kvm|microsoft|xen|zvm)\n");
> fprintf(stderr, "TMPDIR Base directory for template directory (for .needs_tmpdir, default: %s)\n", TEMPDIR);
> fprintf(stderr, "\n");
> @@ -1996,6 +2000,9 @@ void tst_run_tcases(int argc, char *argv[], struct tst_test *self)
> uname(&uval);
> tst_res(TINFO, "Tested kernel: %s %s %s", uval.release, uval.version, uval.machine);
>
> + if (tst_test->min_runtime)
> + tst_test->runtime =tst_test->min_runtime;
If .runtime is set, .min_runtime should not override it. Setting
.runtime < .min_runtime should trigger TBROK during lib setup.
> +
> if (tst_test->runtime)
> context->runtime = multiply_runtime(tst_test->runtime);
>
> diff --git a/testcases/cve/cve-2016-7117.c b/testcases/cve/cve-2016-7117.c
> index dbec2b28b..8c488f447 100644
> --- a/testcases/cve/cve-2016-7117.c
> +++ b/testcases/cve/cve-2016-7117.c
> @@ -151,7 +151,7 @@ static struct tst_test test = {
> .test_all = run,
> .setup = setup,
> .cleanup = cleanup,
> - .runtime = 60,
> + .min_runtime = 60,
The .runtime value in fuzzy_sync tests is calibrated to reliably
reproduce the bug. You can usually set much smaller .min_runtime based
on how long it takes to run 1024 iterations of the fuzzy loop, with some
safety margin (x2?).
> .tags = (const struct tst_tag[]) {
> {"linux-git", "34b88a68f26a"},
> {"CVE", "2016-7117"},
> diff --git a/testcases/kernel/syscalls/preadv2/preadv203.c b/testcases/kernel/syscalls/preadv2/preadv203.c
> index 72a35d3ab..472543e5c 100644
> --- a/testcases/kernel/syscalls/preadv2/preadv203.c
> +++ b/testcases/kernel/syscalls/preadv2/preadv203.c
> @@ -278,6 +278,6 @@ static struct tst_test test = {
> .mntpoint = MNTPOINT,
> .mount_device = 1,
> .all_filesystems = 1,
> - .runtime = 60,
> + .min_runtime = 60,
> .needs_root = 1,
> };
--
Martin Doucha mdoucha@suse.cz
SW Quality Engineer
SUSE LINUX, s.r.o.
CORSO IIa
Krizikova 148/34
186 00 Prague 8
Czech Republic
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