[LTP] [PATCH 6/6] sched/cgroup: Add cfs_bandwidth01

[Cyril Hrubis <chrubis@suse.cz>]

On Thu, May 13, 2021 at 04:21:25PM +0100, Richard Palethorpe via ltp wrote:
> Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
> ---
>  runtest/sched                                 |   1 +
>  .../kernel/sched/cfs-scheduler/.gitignore     |   1 +
>  testcases/kernel/sched/cfs-scheduler/Makefile |   4 +-
>  .../sched/cfs-scheduler/cfs_bandwidth01.c     | 175 ++++++++++++++++++
>  4 files changed, 179 insertions(+), 2 deletions(-)
>  create mode 100644 testcases/kernel/sched/cfs-scheduler/cfs_bandwidth01.c
> 
> diff --git a/runtest/sched b/runtest/sched
> index bfc4f2711..592898723 100644
> --- a/runtest/sched
> +++ b/runtest/sched
> @@ -6,6 +6,7 @@ pth_str03 pth_str03
>  time-schedule01		time-schedule
>  trace_sched01		trace_sched -c 1
>  
> +cfs_bandwidth01 cfs_bandwidth01 -i 5
>  hackbench01 hackbench 50 process 1000
>  hackbench02 hackbench 20 thread 1000
>  
> diff --git a/testcases/kernel/sched/cfs-scheduler/.gitignore b/testcases/kernel/sched/cfs-scheduler/.gitignore
> index db2759e4f..c5dacd6ef 100644
> --- a/testcases/kernel/sched/cfs-scheduler/.gitignore
> +++ b/testcases/kernel/sched/cfs-scheduler/.gitignore
> @@ -1 +1,2 @@
>  /hackbench
> +cfs_bandwidth01
> diff --git a/testcases/kernel/sched/cfs-scheduler/Makefile b/testcases/kernel/sched/cfs-scheduler/Makefile
> index aa3bf8459..2ffe1f7f9 100644
> --- a/testcases/kernel/sched/cfs-scheduler/Makefile
> +++ b/testcases/kernel/sched/cfs-scheduler/Makefile
> @@ -18,8 +18,8 @@
>  
>  top_srcdir		?= ../../../..
>  
> -include $(top_srcdir)/include/mk/env_pre.mk
> +include $(top_srcdir)/include/mk/testcases.mk
>  
> -LDLIBS			+= -lpthread
> +hackbench: LDLIBS			+= -lpthread
>  
>  include $(top_srcdir)/include/mk/generic_leaf_target.mk
> diff --git a/testcases/kernel/sched/cfs-scheduler/cfs_bandwidth01.c b/testcases/kernel/sched/cfs-scheduler/cfs_bandwidth01.c
> new file mode 100644
> index 000000000..b1f98d50f
> --- /dev/null
> +++ b/testcases/kernel/sched/cfs-scheduler/cfs_bandwidth01.c
> @@ -0,0 +1,175 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/* Copyright (c) 2021 SUSE LLC <rpalethorpe@suse.com> */
> +/*\
> + *
> + * [Description]
> + *
> + * Creates a multi-level CGroup hierarchy with the cpu controller
> + * enabled. The leaf groups are populated with "busy" processes which
> + * simulate intermittent cpu load. They spin for some time then sleep
> + * then repeat.
> + *
> + * Both the trunk and leaf groups are set cpu bandwidth limits. The
> + * busy processes will intermittently exceed these limits. Causing
> + * them to be throttled. When they begin sleeping this will then cause
> + * them to be unthrottle.
> + *
> + * The test is known to reproduce an issue with an update to
> + * SLE-15-SP1 (kernel 4.12.14-197.64, bsc#1179093).
> + */
> +
> +#include <stdlib.h>
> +
> +#include "tst_test.h"
> +#include "tst_cgroup.h"
> +#include "tst_timer.h"
> +
> +static const struct tst_cgroup_group *cg_test;
> +static struct tst_cgroup_group *cg_level2, *cg_level3a, *cg_level3b;
> +static struct tst_cgroup_group *cg_workers[3];
> +
> +static void set_cpu_quota(const struct tst_cgroup_group *const cg,
> +			  const float quota_percent)
> +{
> +	const unsigned int period_us = 10000;
> +	const unsigned int quota_us = (quota_percent / 100) * (float)period_us;
> +
> +	if (TST_CGROUP_VER(cg, "cpu") != TST_CGROUP_V1) {
> +		SAFE_CGROUP_PRINTF(cg, "cpu.max",
> +				   "%u %u", quota_us, period_us);
> +	} else {
> +		SAFE_CGROUP_PRINTF(cg, "cpu.max",
> +				   "%u", quota_us);
> +		SAFE_CGROUP_PRINTF(cg, "cpu.cfs_period_us",
> +				  "%u", period_us);
> +	}
> +
> +	tst_res(TINFO, "Set '%s/cpu.max' = '%d %d'",
> +		tst_cgroup_group_name(cg), quota_us, period_us);
> +}
> +
> +static struct tst_cgroup_group *
> +mk_cpu_cgroup(const struct tst_cgroup_group *const cg_parent,
> +	      const char *const cg_child_name,
> +	      const float quota_percent)
> +{
> +	struct tst_cgroup_group *const cg =
> +		tst_cgroup_group_mk(cg_parent, cg_child_name);
> +
> +	set_cpu_quota(cg, quota_percent);
> +
> +	return cg;
> +}
> +
> +static void busy_loop(const unsigned int sleep_ms)
> +{
> +	for (;;) {
> +		tst_timer_start(CLOCK_MONOTONIC_RAW);
> +		while (!tst_timer_expired_ms(20))
> +			;
> +
> +		const int ret = tst_checkpoint_wait(0, sleep_ms);
> +
> +		if (!ret)
> +			exit(0);
> +
> +		if (errno != ETIMEDOUT)
> +			tst_brk(TBROK | TERRNO, "tst_checkpoint_wait");
> +	}
> +}
> +
> +static void fork_busy_procs_in_cgroup(const struct tst_cgroup_group *const cg)
> +{
> +	const unsigned int sleeps_ms[] = {3000, 1000, 10};
> +	const pid_t worker_pid = SAFE_FORK();
> +	size_t i;
> +
> +	if (worker_pid)
> +		return;
> +
> +	for (i = 0; i < ARRAY_SIZE(sleeps_ms); i++) {
> +		const pid_t busy_pid = SAFE_FORK();
> +
> +		if (!busy_pid)
> +			busy_loop(sleeps_ms[i]);
> +
> +		SAFE_CGROUP_PRINTF(cg, "cgroup.procs", "%d", busy_pid);
> +	}
> +
> +	tst_reap_children();
> +
> +	exit(0);
> +}
> +
> +static void do_test(void)
> +{
> +	size_t i;
> +
> +	cg_level2 = tst_cgroup_group_mk(cg_test, "level2");
> +
> +	cg_level3a = tst_cgroup_group_mk(cg_level2, "level3a");
> +	cg_workers[0] = mk_cpu_cgroup(cg_level3a, "worker1", 30);
> +	cg_workers[1] = mk_cpu_cgroup(cg_level3a, "worker2", 20);
> +
> +	cg_level3b = tst_cgroup_group_mk(cg_level2, "level3b");
> +	cg_workers[2] = mk_cpu_cgroup(cg_level3b, "worker3", 30);
> +
> +	for (i = 0; i < ARRAY_SIZE(cg_workers); i++)
> +		fork_busy_procs_in_cgroup(cg_workers[i]);
> +
> +	tst_res(TPASS, "Scheduled bandwidth constrained workers");
> +
> +	sleep(1);
> +
> +	set_cpu_quota(cg_level2, 50);
> +
> +	sleep(2);
> +
> +	TST_CHECKPOINT_WAKE2(0, 3 * 3);
> +	tst_reap_children();
> +
> +	tst_res(TPASS, "Workers exited");
> +}
> +
> +static void setup(void)
> +{
> +	tst_cgroup_require("cpu", NULL);
> +
> +	cg_test = tst_cgroup_get_test_group();
> +}
> +
> +static void cleanup(void)
> +{
> +	size_t i;
> +
> +	for (i = 0; i < ARRAY_SIZE(cg_workers); i++) {
> +		if (cg_workers[i])
> +			cg_workers[i] = tst_cgroup_group_rm(cg_workers[i]);
> +	}
> +
> +	if (cg_level3a)
> +		cg_level3a = tst_cgroup_group_rm(cg_level3a);
> +	if (cg_level3b)
> +		cg_level3b = tst_cgroup_group_rm(cg_level3b);
> +	if (cg_level2)
> +		cg_level2 = tst_cgroup_group_rm(cg_level2);

Hmm, I wonder if we can move this part of the cleanup to the test
library as well. If we add all cgroups the user has created into a FIFO
linked list then this could be implemented as a single loop in the
tst_cgroup_clean().

We would have to loop over the list in the tst_cgroup_group_rm() in
order to remove the about to be removed group from the list as well, but
I guess that this is still worth the trouble.

Other than that the test looks nice and clean.

> +	tst_cgroup_cleanup();
> +}
> +
> +static struct tst_test test = {
> +	.test_all = do_test,
> +	.setup = setup,
> +	.cleanup = cleanup,
> +	.forks_child = 1,
> +	.needs_checkpoints = 1,
> +	.taint_check = TST_TAINT_W | TST_TAINT_D,
> +	.tags = (const struct tst_tag[]) {
> +		{"linux-git", "39f23ce07b93"},
> +		{"linux-git", "b34cb07dde7c"},
> +		{"linux-git", "fe61468b2cbc"},
> +		{"linux-git", "5ab297bab984"},
> +		{"linux-git", "6d4d22468dae"},
> +		{ }
> +	}
> +};
> -- 
> 2.31.1
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp

-- 
Cyril Hrubis
chrubis@suse.cz