Commit | Line | Data |
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2b2d6ff7 | 1 | /* |
c0c0989a | 2 | * SPDX-License-Identifier: LGPL-2.1-only |
2b2d6ff7 | 3 | * |
c0c0989a | 4 | * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
2b2d6ff7 MD |
5 | */ |
6 | ||
c0c0989a MJ |
7 | #ifndef _LTTNG_GETCPU_H |
8 | #define _LTTNG_GETCPU_H | |
9 | ||
2b2d6ff7 | 10 | #include <urcu/compiler.h> |
5e1b7b8b MD |
11 | #include <urcu/system.h> |
12 | #include <urcu/arch.h> | |
13 | ||
247c2ecd MJ |
14 | #include <lttng/ust-getcpu.h> |
15 | ||
16 | ||
17 | /* | |
18 | * Initialize the getcpu plugin if it's present. | |
19 | */ | |
20 | void lttng_ust_getcpu_plugin_init(void) | |
1d18d519 | 21 | __attribute__((visibility("hidden"))); |
5e1b7b8b | 22 | |
247c2ecd MJ |
23 | /* |
24 | * Function pointer to the user provided getcpu callback, can be set at library | |
25 | * initialization by a dlopened plugin or at runtime by a user by calling | |
26 | * lttng_ust_getcpu_override() from the public API. | |
27 | */ | |
28 | extern int (*lttng_ust_get_cpu_sym)(void) | |
1d18d519 | 29 | __attribute__((visibility("hidden"))); |
2b2d6ff7 | 30 | |
fdb4af10 | 31 | #ifdef LTTNG_UST_DEBUG_VALGRIND |
2b2d6ff7 MD |
32 | |
33 | /* | |
34 | * Fallback on cpu 0 if liblttng-ust is build with Valgrind support. | |
35 | * get_cpu() returns the current CPU number. It may change due to | |
36 | * migration, so it is only statistically accurate. | |
37 | */ | |
38 | static inline | |
5e1b7b8b | 39 | int lttng_ust_get_cpu_internal(void) |
2b2d6ff7 MD |
40 | { |
41 | return 0; | |
42 | } | |
43 | ||
44 | #else | |
45 | ||
08bf1cc1 MD |
46 | /* |
47 | * sched_getcpu. | |
48 | */ | |
49 | #ifdef __linux__ | |
50 | ||
787364e8 | 51 | #if !HAVE_SCHED_GETCPU |
08bf1cc1 MD |
52 | #include <sys/syscall.h> |
53 | #define __getcpu(cpu, node, cache) syscall(__NR_getcpu, cpu, node, cache) | |
54 | /* | |
55 | * If getcpu is not implemented in the kernel, use cpu 0 as fallback. | |
56 | */ | |
57 | static inline | |
5e1b7b8b | 58 | int lttng_ust_get_cpu_internal(void) |
08bf1cc1 MD |
59 | { |
60 | int cpu, ret; | |
61 | ||
62 | ret = __getcpu(&cpu, NULL, NULL); | |
63 | if (caa_unlikely(ret < 0)) | |
64 | return 0; | |
787364e8 | 65 | return cpu; |
08bf1cc1 | 66 | } |
787364e8 | 67 | #else /* HAVE_SCHED_GETCPU */ |
08bf1cc1 MD |
68 | #include <sched.h> |
69 | ||
2b2d6ff7 MD |
70 | /* |
71 | * If getcpu is not implemented in the kernel, use cpu 0 as fallback. | |
72 | */ | |
73 | static inline | |
5e1b7b8b | 74 | int lttng_ust_get_cpu_internal(void) |
2b2d6ff7 MD |
75 | { |
76 | int cpu; | |
77 | ||
78 | cpu = sched_getcpu(); | |
79 | if (caa_unlikely(cpu < 0)) | |
80 | return 0; | |
81 | return cpu; | |
82 | } | |
787364e8 | 83 | #endif /* HAVE_SCHED_GETCPU */ |
08bf1cc1 | 84 | |
4327cb7d | 85 | #elif (defined(__FreeBSD__) || defined(__CYGWIN__)) |
08bf1cc1 MD |
86 | |
87 | /* | |
4327cb7d MD |
88 | * FreeBSD and Cygwin do not allow query of CPU ID. Always use CPU |
89 | * number 0, with the assocated performance degradation on SMP. | |
08bf1cc1 MD |
90 | */ |
91 | static inline | |
5e1b7b8b | 92 | int lttng_ust_get_cpu_internal(void) |
08bf1cc1 MD |
93 | { |
94 | return 0; | |
95 | } | |
96 | ||
97 | #else | |
98 | #error "Please add support for your OS into liblttng-ust/compat.h." | |
99 | #endif | |
2b2d6ff7 MD |
100 | |
101 | #endif | |
102 | ||
5e1b7b8b MD |
103 | static inline |
104 | int lttng_ust_get_cpu(void) | |
105 | { | |
247c2ecd | 106 | int (*lttng_ust_get_cpu_current)(void) = CMM_LOAD_SHARED(lttng_ust_get_cpu_sym); |
5e1b7b8b | 107 | |
247c2ecd MJ |
108 | /* |
109 | * Fallback to the internal getcpu implementation if no override was | |
110 | * provided the user. | |
111 | */ | |
112 | if (caa_likely(!lttng_ust_get_cpu_current)) { | |
5e1b7b8b MD |
113 | return lttng_ust_get_cpu_internal(); |
114 | } else { | |
247c2ecd | 115 | return lttng_ust_get_cpu_current(); |
5e1b7b8b MD |
116 | } |
117 | } | |
118 | ||
2b2d6ff7 | 119 | #endif /* _LTTNG_GETCPU_H */ |