For lower HZ values a quota of 1000us is much lower than the amount of microseconds per tick which makes the tests test_cpucg_max and test_cpugc_max_nested fail. Increase the test duration to accommodate for lower HZ values.
Link: https://lore.kernel.org/lkml/20260623194239.GA899029@oak/ Signed-off-by: Joe Simmons-Talbott <[email protected]> --- v2 -> v3: - Instead of changing cpu.max quota extend the test duration based on the HZ value. - don't call pclose() if popen() fails. - check return value of fscanf(). v1 -> v2: - Try checking /proc/config.gz to get the actual kernel HZ value and fallback to 1000 if the value cannot be determined. tools/testing/selftests/cgroup/test_cpu.c | 44 ++++++++++++++++++++--- 1 file changed, 40 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_cpu.c b/tools/testing/selftests/cgroup/test_cpu.c index 7a40d76b9548..feb7eb6a875c 100644 --- a/tools/testing/selftests/cgroup/test_cpu.c +++ b/tools/testing/selftests/cgroup/test_cpu.c @@ -639,6 +639,30 @@ test_cpucg_nested_weight_underprovisioned(const char *root) return run_cpucg_nested_weight_test(root, false); } +/* + * Best effort attempt to get the kernel's HZ value from the config. + * Return the HZ value if found otherwise return -1 to indicate failure. + */ +static long +_get_config_hz(void) +{ + long hz = -1; + FILE *f; + char cmd[256] = "zcat /proc/config.gz 2>/dev/null | grep '^CONFIG_HZ='"; + + f = popen(cmd, "r"); + + if (!f) + return hz; + + if (fscanf(f, "CONFIG_HZ=%ld", &hz) == EOF) + goto out; + +out: + pclose(f); + return hz; +} + /* * This test creates a cgroup with some maximum value within a period, and * verifies that a process in the cgroup is not overscheduled. @@ -646,15 +670,21 @@ test_cpucg_nested_weight_underprovisioned(const char *root) static int test_cpucg_max(const char *root) { int ret = KSFT_FAIL; + long hz = _get_config_hz(); long quota_usec = 1000; long default_period_usec = 100000; /* cpu.max's default period */ - long duration_seconds = 1; + long duration_seconds; - long duration_usec = duration_seconds * USEC_PER_SEC; + long duration_usec; long usage_usec, n_periods, remainder_usec, expected_usage_usec; char *cpucg; char quota_buf[32]; + if (hz == -1) + hz = 1000; + duration_seconds = 1000 / hz; + duration_usec = duration_seconds * USEC_PER_SEC; + snprintf(quota_buf, sizeof(quota_buf), "%ld", quota_usec); cpucg = cg_name(root, "cpucg_test"); @@ -710,15 +740,21 @@ static int test_cpucg_max(const char *root) static int test_cpucg_max_nested(const char *root) { int ret = KSFT_FAIL; + long hz = _get_config_hz(); long quota_usec = 1000; long default_period_usec = 100000; /* cpu.max's default period */ - long duration_seconds = 1; + long duration_seconds; - long duration_usec = duration_seconds * USEC_PER_SEC; + long duration_usec; long usage_usec, n_periods, remainder_usec, expected_usage_usec; char *parent, *child; char quota_buf[32]; + if (hz == -1) + hz = 1000; + duration_seconds = 1000 / hz; + duration_usec = duration_seconds * USEC_PER_SEC; + snprintf(quota_buf, sizeof(quota_buf), "%ld", quota_usec); parent = cg_name(root, "cpucg_parent"); -- 2.54.0
