projects / linux.git / blame
| 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) <[email protected]> | |
| 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> | |
| 13 | #include <linux/kthread.h> | |
| f96e8577 JFG |
14 | #include <linux/module.h> |
| 15 | #include <linux/printk.h> | |
| 16 | #include <linux/string.h> | |
| 17 | ||
| 18 | static ulong delay = 100; | |
| 19 | static char test_mode[10] = "irq"; | |
| 20 | ||
| 21 | module_param_named(delay, delay, ulong, S_IRUGO); | |
| 22 | module_param_string(test_mode, test_mode, 10, S_IRUGO); | |
| 23 | MODULE_PARM_DESC(delay, "Period in microseconds (100 uS default)"); | |
| 24 | MODULE_PARM_DESC(test_mode, "Mode of the test such as preempt or irq (default irq)"); | |
| 25 | ||
| 26 | static void busy_wait(ulong time) | |
| 27 | { | |
| 12ad0cb2 SRV |
28 | u64 start, end; |
| 29 | start = trace_clock_local(); | |
| f96e8577 | 30 | do { |
| 12ad0cb2 | 31 | end = trace_clock_local(); |
| f96e8577 JFG |
32 | if (kthread_should_stop()) |
| 33 | break; | |
| 12ad0cb2 | 34 | } while ((end - start) < (time * 1000)); |
| f96e8577 JFG |
35 | } |
| 36 | ||
| 518eeca0 | 37 | static int preemptirq_delay_run(void *data) |
| f96e8577 JFG |
38 | { |
| 39 | unsigned long flags; | |
| 40 | ||
| 41 | if (!strcmp(test_mode, "irq")) { | |
| 42 | local_irq_save(flags); | |
| 43 | busy_wait(delay); | |
| 44 | local_irq_restore(flags); | |
| 45 | } else if (!strcmp(test_mode, "preempt")) { | |
| 46 | preempt_disable(); | |
| 47 | busy_wait(delay); | |
| 48 | preempt_enable(); | |
| 49 | } | |
| 50 | ||
| 51 | return 0; | |
| 52 | } | |
| 53 | ||
| 54 | static int __init preemptirq_delay_init(void) | |
| 55 | { | |
| 56 | char task_name[50]; | |
| 57 | struct task_struct *test_task; | |
| 58 | ||
| 59 | snprintf(task_name, sizeof(task_name), "%s_test", test_mode); | |
| 60 | ||
| 61 | test_task = kthread_run(preemptirq_delay_run, NULL, task_name); | |
| 62 | return PTR_ERR_OR_ZERO(test_task); | |
| 63 | } | |
| 64 | ||
| 65 | static void __exit preemptirq_delay_exit(void) | |
| 66 | { | |
| 67 | return; | |
| 68 | } | |
| 69 | ||
| 70 | module_init(preemptirq_delay_init) | |
| 71 | module_exit(preemptirq_delay_exit) | |
| 72 | MODULE_LICENSE("GPL v2"); |