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1 #include <linux/init.h>
2 #include <linux/kthread.h>
3 #include <linux/hrtimer.h>
4 #include <linux/fs.h>
5 #include <linux/debugfs.h>
6 #include <linux/export.h>
7 #include <linux/spinlock.h>
8 
9 
ss_get(void * data,u64 * val)10 static int ss_get(void *data, u64 *val)
11 {
12 	ktime_t start, finish;
13 	int loops;
14 	int cont;
15 	DEFINE_RAW_SPINLOCK(ss_spin);
16 
17 	loops = 1000000;
18 	cont = 1;
19 
20 	start = ktime_get();
21 
22 	while (cont) {
23 		raw_spin_lock(&ss_spin);
24 		loops--;
25 		if (loops == 0)
26 			cont = 0;
27 		raw_spin_unlock(&ss_spin);
28 	}
29 
30 	finish = ktime_get();
31 
32 	*val = ktime_us_delta(finish, start);
33 
34 	return 0;
35 }
36 
37 DEFINE_SIMPLE_ATTRIBUTE(fops_ss, ss_get, NULL, "%llu\n");
38 
39 
40 
41 struct spin_multi_state {
42 	raw_spinlock_t lock;
43 	atomic_t start_wait;
44 	atomic_t enter_wait;
45 	atomic_t exit_wait;
46 	int loops;
47 };
48 
49 struct spin_multi_per_thread {
50 	struct spin_multi_state *state;
51 	ktime_t start;
52 };
53 
multi_other(void * data)54 static int multi_other(void *data)
55 {
56 	int loops;
57 	int cont;
58 	struct spin_multi_per_thread *pt = data;
59 	struct spin_multi_state *s = pt->state;
60 
61 	loops = s->loops;
62 	cont = 1;
63 
64 	atomic_dec(&s->enter_wait);
65 
66 	while (atomic_read(&s->enter_wait))
67 		; /* spin */
68 
69 	pt->start = ktime_get();
70 
71 	atomic_dec(&s->start_wait);
72 
73 	while (atomic_read(&s->start_wait))
74 		; /* spin */
75 
76 	while (cont) {
77 		raw_spin_lock(&s->lock);
78 		loops--;
79 		if (loops == 0)
80 			cont = 0;
81 		raw_spin_unlock(&s->lock);
82 	}
83 
84 	atomic_dec(&s->exit_wait);
85 	while (atomic_read(&s->exit_wait))
86 		; /* spin */
87 	return 0;
88 }
89 
multi_get(void * data,u64 * val)90 static int multi_get(void *data, u64 *val)
91 {
92 	ktime_t finish;
93 	struct spin_multi_state ms;
94 	struct spin_multi_per_thread t1, t2;
95 
96 	ms.lock = __RAW_SPIN_LOCK_UNLOCKED("multi_get");
97 	ms.loops = 1000000;
98 
99 	atomic_set(&ms.start_wait, 2);
100 	atomic_set(&ms.enter_wait, 2);
101 	atomic_set(&ms.exit_wait, 2);
102 	t1.state = &ms;
103 	t2.state = &ms;
104 
105 	kthread_run(multi_other, &t2, "multi_get");
106 
107 	multi_other(&t1);
108 
109 	finish = ktime_get();
110 
111 	*val = ktime_us_delta(finish, t1.start);
112 
113 	return 0;
114 }
115 
116 DEFINE_SIMPLE_ATTRIBUTE(fops_multi, multi_get, NULL, "%llu\n");
117 
118 
119 extern struct dentry *mips_debugfs_dir;
spinlock_test(void)120 static int __init spinlock_test(void)
121 {
122 	struct dentry *d;
123 
124 	if (!mips_debugfs_dir)
125 		return -ENODEV;
126 
127 	d = debugfs_create_file("spin_single", S_IRUGO,
128 				mips_debugfs_dir, NULL,
129 				&fops_ss);
130 	if (!d)
131 		return -ENOMEM;
132 
133 	d = debugfs_create_file("spin_multi", S_IRUGO,
134 				mips_debugfs_dir, NULL,
135 				&fops_multi);
136 	if (!d)
137 		return -ENOMEM;
138 
139 	return 0;
140 }
141 device_initcall(spinlock_test);
142