From a2703c2980c0776e9be7d8f9e144afd054dddb12 Mon Sep 17 00:00:00 2001 From: Joe Simmons-Talbott Date: Fri, 26 Jun 2026 16:29:22 -0400 Subject: [PATCH] selftests/cgroup: Adjust cpu test duration based on HZ MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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/20260625203307.1114538-1-joest@redhat.com/ Signed-off-by: Joe Simmons-Talbott Acked-by: Michal Koutný Signed-off-by: Tejun Heo --- .../cgroup/lib/include/cgroup_util.h | 1 + tools/testing/selftests/cgroup/test_cpu.c | 43 ++++++++++++++++--- 2 files changed, 38 insertions(+), 6 deletions(-) diff --git a/tools/testing/selftests/cgroup/lib/include/cgroup_util.h b/tools/testing/selftests/cgroup/lib/include/cgroup_util.h index febc1723d090..8ebb2b4d4ec0 100644 --- a/tools/testing/selftests/cgroup/lib/include/cgroup_util.h +++ b/tools/testing/selftests/cgroup/lib/include/cgroup_util.h @@ -8,6 +8,7 @@ #define MB(x) (x << 20) +#define NSEC_PER_USEC 1000L #define USEC_PER_SEC 1000000L #define NSEC_PER_SEC 1000000000L diff --git a/tools/testing/selftests/cgroup/test_cpu.c b/tools/testing/selftests/cgroup/test_cpu.c index 7a40d76b9548..a5eccfcabef5 100644 --- a/tools/testing/selftests/cgroup/test_cpu.c +++ b/tools/testing/selftests/cgroup/test_cpu.c @@ -639,6 +639,31 @@ 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 1000 (the default) to + * indicate failure. + */ +static long +get_config_hz(void) +{ + long hz = 1000; + 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 +671,18 @@ 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_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]; + duration_usec = duration_seconds * USEC_PER_SEC * 1000 / hz; + snprintf(quota_buf, sizeof(quota_buf), "%ld", quota_usec); cpucg = cg_name(root, "cpucg_test"); @@ -670,8 +698,8 @@ static int test_cpucg_max(const char *root) struct cpu_hog_func_param param = { .nprocs = 1, .ts = { - .tv_sec = duration_seconds, - .tv_nsec = 0, + .tv_sec = duration_usec / USEC_PER_SEC, + .tv_nsec = duration_usec % USEC_PER_SEC * NSEC_PER_USEC, }, .clock_type = CPU_HOG_CLOCK_WALL, }; @@ -710,15 +738,18 @@ 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_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]; + duration_usec = duration_seconds * USEC_PER_SEC * 1000 / hz; + snprintf(quota_buf, sizeof(quota_buf), "%ld", quota_usec); parent = cg_name(root, "cpucg_parent"); @@ -741,8 +772,8 @@ static int test_cpucg_max_nested(const char *root) struct cpu_hog_func_param param = { .nprocs = 1, .ts = { - .tv_sec = duration_seconds, - .tv_nsec = 0, + .tv_sec = duration_usec / USEC_PER_SEC, + .tv_nsec = duration_usec % USEC_PER_SEC * NSEC_PER_USEC, }, .clock_type = CPU_HOG_CLOCK_WALL, };