On Thu, Jun 25, 2026 at 3:54 PM Joe Simmons-Talbott <[email protected]> wrote: >
+mailing lists +Tao Cui > 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/[email protected]/ > Signed-off-by: Joe Simmons-Talbott <[email protected]> > --- > v3 -> v4: > - Use usec for adjusting test duration for better accuracy. > - Remove underscore from static function > - Use 1000 as the fallback value for hz since it's the default. > > 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. > > .../cgroup/lib/include/cgroup_util.h | 1 + > tools/testing/selftests/cgroup/test_cpu.c | 47 ++++++++++++++++--- > 2 files changed, 42 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..1f280c1db68a 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 +671,20 @@ 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, duration_sec, duration_nsec; > 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; > + duration_sec = duration_usec / USEC_PER_SEC; > + duration_nsec = duration_usec % USEC_PER_SEC * NSEC_PER_USEC; > + > snprintf(quota_buf, sizeof(quota_buf), "%ld", quota_usec); > > cpucg = cg_name(root, "cpucg_test"); > @@ -670,8 +700,8 @@ 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_sec, > + .tv_nsec = duration_nsec, > }, > .clock_type = CPU_HOG_CLOCK_WALL, > }; > @@ -710,15 +740,20 @@ 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, duration_sec, duration_nsec; > 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; > + duration_sec = duration_usec / USEC_PER_SEC; > + duration_nsec = duration_usec % USEC_PER_SEC * NSEC_PER_USEC; > + > snprintf(quota_buf, sizeof(quota_buf), "%ld", quota_usec); > > parent = cg_name(root, "cpucg_parent"); > @@ -741,8 +776,8 @@ 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_sec, > + .tv_nsec = duration_nsec, > }, > .clock_type = CPU_HOG_CLOCK_WALL, > }; > -- > 2.54.0 >
