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

[Richard Palethorpe <rpalethorpe@suse.de>]

Hello,

Cyril Hrubis <chrubis@suse.cz> writes:

> 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.

This sounds good. We probably need to check if the groups have processes
in them to print a nice error message. My main concern with automatic
cleanup is confusing errors from deep in the lib.

>
> 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


-- 
Thank you,
Richard.