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1 | /* test-cmpxchg.c |
2 | * |
3 | * Test time spent in a LTTng instrumentation probe. |
4 | */ |
5 | |
6 | |
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7 | #include <linux/jiffies.h> |
8 | #include <linux/compiler.h> |
9 | #include <linux/init.h> |
10 | #include <linux/module.h> |
11 | |
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12 | #if 0 |
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13 | #define cmpxchg_up(ptr,o,n)\ |
14 | ((__typeof__(*(ptr)))__cmpxchg_up((ptr),(unsigned long)(o),\ |
15 | (unsigned long)(n),sizeof(*(ptr)))) |
16 | static inline unsigned long __cmpxchg_up(volatile void *ptr, unsigned long old, |
17 | unsigned long new, int size) |
18 | { |
19 | unsigned long prev; |
20 | switch (size) { |
21 | case 1: |
22 | __asm__ __volatile__("cmpxchgb %b1,%2" |
23 | : "=a"(prev) |
24 | : "q"(new), "m"(*__xg(ptr)), "0"(old) |
25 | : "memory"); |
26 | return prev; |
27 | case 2: |
28 | __asm__ __volatile__("cmpxchgw %w1,%2" |
29 | : "=a"(prev) |
30 | : "r"(new), "m"(*__xg(ptr)), "0"(old) |
31 | : "memory"); |
32 | return prev; |
33 | case 4: |
34 | __asm__ __volatile__("cmpxchgl %1,%2" |
35 | : "=a"(prev) |
36 | : "r"(new), "m"(*__xg(ptr)), "0"(old) |
37 | : "memory"); |
38 | return prev; |
39 | } |
40 | return old; |
41 | } |
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42 | #endif //0 |
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43 | |
44 | #define NR_LOOPS 20000 |
45 | |
46 | volatile int test_val = 100; |
47 | |
48 | |
49 | static inline void do_test(void) |
50 | { |
51 | int val, ret; |
52 | |
53 | val = test_val; |
54 | |
55 | ret = cmpxchg_up(&test_val, val, val+1); |
56 | } |
57 | |
58 | static int ltt_test_init(void) |
59 | { |
60 | unsigned int i; |
61 | cycles_t time1, time2, time; |
62 | cycles_t max_time = 0, min_time = 18446744073709551615ULL; /* (2^64)-1 */ |
63 | cycles_t tot_time = 0; |
64 | unsigned long flags; |
65 | printk(KERN_ALERT "test init\n"); |
66 | |
67 | local_irq_save(flags); |
68 | time1 = get_cycles(); |
69 | for(i=0; i<NR_LOOPS; i++) { |
70 | //for(int j=0; j<10; j++) { |
71 | do_test(); |
72 | //} |
73 | //max_time = max(max_time, time); |
74 | //min_time = min(min_time, time); |
75 | //printk("val : %d\n", test_val); |
76 | } |
77 | time2 = get_cycles(); |
78 | local_irq_restore(flags); |
79 | time = time2 - time1; |
80 | tot_time += time; |
81 | |
82 | printk(KERN_ALERT "test results : time non locked cmpxchg\n"); |
83 | printk(KERN_ALERT "number of loops : %d\n", NR_LOOPS); |
84 | printk(KERN_ALERT "total time : %llu\n", tot_time); |
85 | //printk(KERN_ALERT "min : %llu\n", min_time); |
86 | //printk(KERN_ALERT "max : %llu\n", max_time); |
87 | |
88 | printk(KERN_ALERT "test end\n"); |
89 | |
90 | return -EAGAIN; /* Fail will directly unload the module */ |
91 | } |
92 | |
93 | static void ltt_test_exit(void) |
94 | { |
95 | printk(KERN_ALERT "test exit\n"); |
96 | } |
97 | |
98 | module_init(ltt_test_init) |
99 | module_exit(ltt_test_exit) |
100 | |
101 | MODULE_LICENSE("GPL"); |
102 | MODULE_AUTHOR("Mathieu Desnoyers"); |
103 | MODULE_DESCRIPTION("Linux Trace Toolkit Test"); |
104 | |