73 lines
1.6 KiB
C
73 lines
1.6 KiB
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/kthread.h>
|
|
#include <linux/module.h>
|
|
#include <linux/printk.h>
|
|
#include <linux/string.h>
|
|
|
|
static ulong delay = 100;
|
|
static char test_mode[10] = "irq";
|
|
|
|
module_param_named(delay, delay, ulong, S_IRUGO);
|
|
module_param_string(test_mode, test_mode, 10, S_IRUGO);
|
|
MODULE_PARM_DESC(delay, "Period in microseconds (100 uS default)");
|
|
MODULE_PARM_DESC(test_mode, "Mode of the test such as preempt or irq (default irq)");
|
|
|
|
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 int preemptirq_delay_run(void *data)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (!strcmp(test_mode, "irq")) {
|
|
local_irq_save(flags);
|
|
busy_wait(delay);
|
|
local_irq_restore(flags);
|
|
} else if (!strcmp(test_mode, "preempt")) {
|
|
preempt_disable();
|
|
busy_wait(delay);
|
|
preempt_enable();
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int __init preemptirq_delay_init(void)
|
|
{
|
|
char task_name[50];
|
|
struct task_struct *test_task;
|
|
|
|
snprintf(task_name, sizeof(task_name), "%s_test", test_mode);
|
|
|
|
test_task = kthread_run(preemptirq_delay_run, NULL, task_name);
|
|
return PTR_ERR_OR_ZERO(test_task);
|
|
}
|
|
|
|
static void __exit preemptirq_delay_exit(void)
|
|
{
|
|
return;
|
|
}
|
|
|
|
module_init(preemptirq_delay_init)
|
|
module_exit(preemptirq_delay_exit)
|
|
MODULE_LICENSE("GPL v2");
|