[thirdparty/linux.git] / kernel / trace / preemptirq_delay_test.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Preempt / IRQ disable delay thread to test latency tracers
 *
 * Copyright (C) 2018 Joel Fernandes (Google) <joel@joelfernandes.org>
 */

#include <linux/trace_clock.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/string.h>
#include <linux/sysfs.h>

static ulong delay = 100;
static char test_mode[12] = "irq";
static uint burst_size = 1;

module_param_named(delay, delay, ulong, 0444);
module_param_string(test_mode, test_mode, 12, 0444);
module_param_named(burst_size, burst_size, uint, 0444);
MODULE_PARM_DESC(delay, "Period in microseconds (100 us default)");
MODULE_PARM_DESC(test_mode, "Mode of the test such as preempt, irq, or alternate (default irq)");
MODULE_PARM_DESC(burst_size, "The size of a burst (default 1)");

#define MIN(x, y) ((x) < (y) ? (x) : (y))

static void busy_wait(ulong time)
{
	u64 start, end;
	start = trace_clock_local();
	do {
		end = trace_clock_local();
		if (kthread_should_stop())
			break;
	} while ((end - start) < (time * 1000));
}

static __always_inline void irqoff_test(void)
{
	unsigned long flags;
	local_irq_save(flags);
	busy_wait(delay);
	local_irq_restore(flags);
}

static __always_inline void preemptoff_test(void)
{
	preempt_disable();
	busy_wait(delay);
	preempt_enable();
}

static void execute_preemptirqtest(int idx)
{
	if (!strcmp(test_mode, "irq"))
		irqoff_test();
	else if (!strcmp(test_mode, "preempt"))
		preemptoff_test();
	else if (!strcmp(test_mode, "alternate")) {
		if (idx % 2 == 0)
			irqoff_test();
		else
			preemptoff_test();
	}
}

#define DECLARE_TESTFN(POSTFIX)				\
	static void preemptirqtest_##POSTFIX(int idx)	\
	{						\
		execute_preemptirqtest(idx);		\
	}						\

/*
 * We create 10 different functions, so that we can get 10 different
 * backtraces.
 */
DECLARE_TESTFN(0)
DECLARE_TESTFN(1)
DECLARE_TESTFN(2)
DECLARE_TESTFN(3)
DECLARE_TESTFN(4)
DECLARE_TESTFN(5)
DECLARE_TESTFN(6)
DECLARE_TESTFN(7)
DECLARE_TESTFN(8)
DECLARE_TESTFN(9)

static void (*testfuncs[])(int)  = {
	preemptirqtest_0,
	preemptirqtest_1,
	preemptirqtest_2,
	preemptirqtest_3,
	preemptirqtest_4,
	preemptirqtest_5,
	preemptirqtest_6,
	preemptirqtest_7,
	preemptirqtest_8,
	preemptirqtest_9,
};

#define NR_TEST_FUNCS ARRAY_SIZE(testfuncs)

static int preemptirq_delay_run(void *data)
{
	int i;
	int s = MIN(burst_size, NR_TEST_FUNCS);

	for (i = 0; i < s; i++)
		(testfuncs[i])(i);

	set_current_state(TASK_INTERRUPTIBLE);
	while (!kthread_should_stop()) {
		schedule();
		set_current_state(TASK_INTERRUPTIBLE);
	}

	__set_current_state(TASK_RUNNING);

	return 0;
}

static int preemptirq_run_test(void)
{
	struct task_struct *task;

	char task_name[50];

	snprintf(task_name, sizeof(task_name), "%s_test", test_mode);
	task =  kthread_run(preemptirq_delay_run, NULL, task_name);
	if (IS_ERR(task))
		return PTR_ERR(task);
	if (task)
		kthread_stop(task);
	return 0;
}


static ssize_t trigger_store(struct kobject *kobj, struct kobj_attribute *attr,
			 const char *buf, size_t count)
{
	ssize_t ret;

	ret = preemptirq_run_test();
	if (ret)
		return ret;
	return count;
}

static struct kobj_attribute trigger_attribute =
	__ATTR(trigger, 0200, NULL, trigger_store);

static struct attribute *attrs[] = {
	&trigger_attribute.attr,
	NULL,
};

static struct attribute_group attr_group = {
	.attrs = attrs,
};

static struct kobject *preemptirq_delay_kobj;

static int __init preemptirq_delay_init(void)
{
	int retval;

	retval = preemptirq_run_test();
	if (retval != 0)
		return retval;

	preemptirq_delay_kobj = kobject_create_and_add("preemptirq_delay_test",
						       kernel_kobj);
	if (!preemptirq_delay_kobj)
		return -ENOMEM;

	retval = sysfs_create_group(preemptirq_delay_kobj, &attr_group);
	if (retval)
		kobject_put(preemptirq_delay_kobj);

	return retval;
}

static void __exit preemptirq_delay_exit(void)
{
	kobject_put(preemptirq_delay_kobj);
}

module_init(preemptirq_delay_init)
module_exit(preemptirq_delay_exit)
MODULE_LICENSE("GPL v2");
Commit	Line	Data
f96e8577 JFG	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* Preempt / IRQ disable delay thread to test latency tracers
	4	*
	5	* Copyright (C) 2018 Joel Fernandes (Google) <joel@joelfernandes.org>
	6	*/
	7
12ad0cb2	8	#include <linux/trace_clock.h>
f96e8577 JFG	9	#include <linux/delay.h>
	10	#include <linux/interrupt.h>
	11	#include <linux/irq.h>
	12	#include <linux/kernel.h>
79393723	13	#include <linux/kobject.h>
f96e8577	14	#include <linux/kthread.h>
f96e8577 JFG	15	#include <linux/module.h>
	16	#include <linux/printk.h>
	17	#include <linux/string.h>
79393723	18	#include <linux/sysfs.h>
f96e8577 JFG	19
f96e8577 JFG	20	static ulong delay = 100;
79393723 VRB	21	static char test_mode[12] = "irq";
79393723 VRB	22	static uint burst_size = 1;
f96e8577	23
79393723 VRB	24	module_param_named(delay, delay, ulong, 0444);
	25	module_param_string(test_mode, test_mode, 12, 0444);
	26	module_param_named(burst_size, burst_size, uint, 0444);
	27	MODULE_PARM_DESC(delay, "Period in microseconds (100 us default)");
	28	MODULE_PARM_DESC(test_mode, "Mode of the test such as preempt, irq, or alternate (default irq)");
	29	MODULE_PARM_DESC(burst_size, "The size of a burst (default 1)");
	30
	31	#define MIN(x, y) ((x) < (y) ? (x) : (y))
f96e8577 JFG	32
	33	static void busy_wait(ulong time)
	34	{
12ad0cb2 SRV	35	u64 start, end;
12ad0cb2 SRV	36	start = trace_clock_local();
f96e8577	37	do {
12ad0cb2	38	end = trace_clock_local();
f96e8577 JFG	39	if (kthread_should_stop())
f96e8577 JFG	40	break;
12ad0cb2	41	} while ((end - start) < (time * 1000));
f96e8577 JFG	42	}
f96e8577 JFG	43
79393723	44	static __always_inline void irqoff_test(void)
f96e8577 JFG	45	{
f96e8577 JFG	46	unsigned long flags;
79393723 VRB	47	local_irq_save(flags);
	48	busy_wait(delay);
	49	local_irq_restore(flags);
	50	}
f96e8577	51
79393723 VRB	52	static __always_inline void preemptoff_test(void)
	53	{
	54	preempt_disable();
	55	busy_wait(delay);
	56	preempt_enable();
	57	}
	58
	59	static void execute_preemptirqtest(int idx)
	60	{
	61	if (!strcmp(test_mode, "irq"))
	62	irqoff_test();
	63	else if (!strcmp(test_mode, "preempt"))
	64	preemptoff_test();
	65	else if (!strcmp(test_mode, "alternate")) {
	66	if (idx % 2 == 0)
	67	irqoff_test();
	68	else
	69	preemptoff_test();
f96e8577	70	}
79393723 VRB	71	}
	72
	73	#define DECLARE_TESTFN(POSTFIX) \
	74	static void preemptirqtest_##POSTFIX(int idx) \
	75	{ \
	76	execute_preemptirqtest(idx); \
	77	} \
f96e8577	78
79393723 VRB	79	/*
	80	* We create 10 different functions, so that we can get 10 different
	81	* backtraces.
	82	*/
	83	DECLARE_TESTFN(0)
	84	DECLARE_TESTFN(1)
	85	DECLARE_TESTFN(2)
	86	DECLARE_TESTFN(3)
	87	DECLARE_TESTFN(4)
	88	DECLARE_TESTFN(5)
	89	DECLARE_TESTFN(6)
	90	DECLARE_TESTFN(7)
	91	DECLARE_TESTFN(8)
	92	DECLARE_TESTFN(9)
	93
	94	static void (*testfuncs[])(int) = {
	95	preemptirqtest_0,
	96	preemptirqtest_1,
	97	preemptirqtest_2,
	98	preemptirqtest_3,
	99	preemptirqtest_4,
	100	preemptirqtest_5,
	101	preemptirqtest_6,
	102	preemptirqtest_7,
	103	preemptirqtest_8,
	104	preemptirqtest_9,
	105	};
	106
	107	#define NR_TEST_FUNCS ARRAY_SIZE(testfuncs)
	108
	109	static int preemptirq_delay_run(void *data)
	110	{
	111	int i;
	112	int s = MIN(burst_size, NR_TEST_FUNCS);
	113
	114	for (i = 0; i < s; i++)
	115	(testfuncs[i])(i);
d16a8c31 SRV	116
	117	set_current_state(TASK_INTERRUPTIBLE);
	118	while (!kthread_should_stop()) {
	119	schedule();
	120	set_current_state(TASK_INTERRUPTIBLE);
	121	}
	122
	123	__set_current_state(TASK_RUNNING);
	124
f96e8577 JFG	125	return 0;
	126	}
	127
d16a8c31	128	static int preemptirq_run_test(void)
f96e8577	129	{
d16a8c31 SRV	130	struct task_struct *task;
d16a8c31 SRV	131
f96e8577	132	char task_name[50];
f96e8577 JFG	133
f96e8577 JFG	134	snprintf(task_name, sizeof(task_name), "%s_test", test_mode);
d16a8c31 SRV	135	task = kthread_run(preemptirq_delay_run, NULL, task_name);
	136	if (IS_ERR(task))
	137	return PTR_ERR(task);
	138	if (task)
	139	kthread_stop(task);
	140	return 0;
79393723 VRB	141	}
	142
	143
	144	static ssize_t trigger_store(struct kobject kobj, struct kobj_attribute attr,
	145	const char *buf, size_t count)
	146	{
d16a8c31 SRV	147	ssize_t ret;
	148
	149	ret = preemptirq_run_test();
	150	if (ret)
	151	return ret;
79393723 VRB	152	return count;
	153	}
	154
	155	static struct kobj_attribute trigger_attribute =
	156	__ATTR(trigger, 0200, NULL, trigger_store);
	157
	158	static struct attribute *attrs[] = {
	159	&trigger_attribute.attr,
	160	NULL,
	161	};
	162
	163	static struct attribute_group attr_group = {
	164	.attrs = attrs,
	165	};
	166
	167	static struct kobject *preemptirq_delay_kobj;
	168
	169	static int __init preemptirq_delay_init(void)
	170	{
79393723 VRB	171	int retval;
79393723 VRB	172
d16a8c31	173	retval = preemptirq_run_test();
79393723 VRB	174	if (retval != 0)
	175	return retval;
	176
	177	preemptirq_delay_kobj = kobject_create_and_add("preemptirq_delay_test",
	178	kernel_kobj);
	179	if (!preemptirq_delay_kobj)
	180	return -ENOMEM;
	181
	182	retval = sysfs_create_group(preemptirq_delay_kobj, &attr_group);
	183	if (retval)
	184	kobject_put(preemptirq_delay_kobj);
f96e8577	185
79393723	186	return retval;
f96e8577 JFG	187	}
	188
	189	static void __exit preemptirq_delay_exit(void)
	190	{
79393723	191	kobject_put(preemptirq_delay_kobj);
f96e8577 JFG	192	}
	193
	194	module_init(preemptirq_delay_init)
	195	module_exit(preemptirq_delay_exit)
	196	MODULE_LICENSE("GPL v2");