* Re: [PATCH v4] selftests/cgroup: Adjust cpu test duration based on HZ
[not found] <20260625195415.1102409-1-joest@redhat.com>
@ 2026-06-25 20:20 ` Joe Simmons-Talbott
2026-06-25 20:30 ` Joe Simmons-Talbott
0 siblings, 1 reply; 2+ messages in thread
From: Joe Simmons-Talbott @ 2026-06-25 20:20 UTC (permalink / raw)
To: Tejun Heo, Johannes Weiner, Michal Koutný, Shuah Khan
Cc: Nhat Pham, Guopeng Zhang, Shakeel Butt, Li Wang, Sebastian Chlad,
cgroups, linux-kselftest, linux-kernel, cui.tao
On Thu, Jun 25, 2026 at 3:54 PM Joe Simmons-Talbott <joest@redhat.com> 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/20260624160358.430354-1-joest@redhat.com/
> Signed-off-by: Joe Simmons-Talbott <joest@redhat.com>
> ---
> 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
>
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v4] selftests/cgroup: Adjust cpu test duration based on HZ
2026-06-25 20:20 ` [PATCH v4] selftests/cgroup: Adjust cpu test duration based on HZ Joe Simmons-Talbott
@ 2026-06-25 20:30 ` Joe Simmons-Talbott
0 siblings, 0 replies; 2+ messages in thread
From: Joe Simmons-Talbott @ 2026-06-25 20:30 UTC (permalink / raw)
To: Joe Simmons-Talbott
Cc: Tejun Heo, Johannes Weiner, Michal Koutný, Shuah Khan,
Nhat Pham, Guopeng Zhang, Shakeel Butt, Li Wang, Sebastian Chlad,
cgroups, linux-kselftest, linux-kernel, cui.tao
On Thu, Jun 25, 2026 at 04:20:25PM -0400, Joe Simmons-Talbott wrote:
> On Thu, Jun 25, 2026 at 3:54 PM Joe Simmons-Talbott <joest@redhat.com> wrote:
> >
>
> +mailing lists
> +Tao Cui
I messed this up. Please ignore this patch. I will resend.
Thanks,
Joe
>
>
>
> > 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/20260624160358.430354-1-joest@redhat.com/
> > Signed-off-by: Joe Simmons-Talbott <joest@redhat.com>
> > ---
> > 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
> >
^ permalink raw reply [flat|nested] 2+ messages in thread
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[not found] <20260625195415.1102409-1-joest@redhat.com>
2026-06-25 20:20 ` [PATCH v4] selftests/cgroup: Adjust cpu test duration based on HZ Joe Simmons-Talbott
2026-06-25 20:30 ` Joe Simmons-Talbott
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