Commit | Line | Data |
---|---|---|
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 | ||
1d18d519 MJ |
14 | void lttng_ust_getcpu_init(void) |
15 | __attribute__((visibility("hidden"))); | |
5e1b7b8b | 16 | |
1d18d519 MJ |
17 | extern int (*lttng_get_cpu)(void) |
18 | __attribute__((visibility("hidden"))); | |
2b2d6ff7 | 19 | |
fdb4af10 | 20 | #ifdef LTTNG_UST_DEBUG_VALGRIND |
2b2d6ff7 MD |
21 | |
22 | /* | |
23 | * Fallback on cpu 0 if liblttng-ust is build with Valgrind support. | |
24 | * get_cpu() returns the current CPU number. It may change due to | |
25 | * migration, so it is only statistically accurate. | |
26 | */ | |
27 | static inline | |
5e1b7b8b | 28 | int lttng_ust_get_cpu_internal(void) |
2b2d6ff7 MD |
29 | { |
30 | return 0; | |
31 | } | |
32 | ||
33 | #else | |
34 | ||
08bf1cc1 MD |
35 | /* |
36 | * sched_getcpu. | |
37 | */ | |
38 | #ifdef __linux__ | |
39 | ||
787364e8 | 40 | #if !HAVE_SCHED_GETCPU |
08bf1cc1 MD |
41 | #include <sys/syscall.h> |
42 | #define __getcpu(cpu, node, cache) syscall(__NR_getcpu, cpu, node, cache) | |
43 | /* | |
44 | * If getcpu is not implemented in the kernel, use cpu 0 as fallback. | |
45 | */ | |
46 | static inline | |
5e1b7b8b | 47 | int lttng_ust_get_cpu_internal(void) |
08bf1cc1 MD |
48 | { |
49 | int cpu, ret; | |
50 | ||
51 | ret = __getcpu(&cpu, NULL, NULL); | |
52 | if (caa_unlikely(ret < 0)) | |
53 | return 0; | |
787364e8 | 54 | return cpu; |
08bf1cc1 | 55 | } |
787364e8 | 56 | #else /* HAVE_SCHED_GETCPU */ |
08bf1cc1 MD |
57 | #include <sched.h> |
58 | ||
2b2d6ff7 MD |
59 | /* |
60 | * If getcpu is not implemented in the kernel, use cpu 0 as fallback. | |
61 | */ | |
62 | static inline | |
5e1b7b8b | 63 | int lttng_ust_get_cpu_internal(void) |
2b2d6ff7 MD |
64 | { |
65 | int cpu; | |
66 | ||
67 | cpu = sched_getcpu(); | |
68 | if (caa_unlikely(cpu < 0)) | |
69 | return 0; | |
70 | return cpu; | |
71 | } | |
787364e8 | 72 | #endif /* HAVE_SCHED_GETCPU */ |
08bf1cc1 | 73 | |
4327cb7d | 74 | #elif (defined(__FreeBSD__) || defined(__CYGWIN__)) |
08bf1cc1 MD |
75 | |
76 | /* | |
4327cb7d MD |
77 | * FreeBSD and Cygwin do not allow query of CPU ID. Always use CPU |
78 | * number 0, with the assocated performance degradation on SMP. | |
08bf1cc1 MD |
79 | */ |
80 | static inline | |
5e1b7b8b | 81 | int lttng_ust_get_cpu_internal(void) |
08bf1cc1 MD |
82 | { |
83 | return 0; | |
84 | } | |
85 | ||
86 | #else | |
87 | #error "Please add support for your OS into liblttng-ust/compat.h." | |
88 | #endif | |
2b2d6ff7 MD |
89 | |
90 | #endif | |
91 | ||
5e1b7b8b MD |
92 | static inline |
93 | int lttng_ust_get_cpu(void) | |
94 | { | |
95 | int (*getcpu)(void) = CMM_LOAD_SHARED(lttng_get_cpu); | |
96 | ||
97 | if (caa_likely(!getcpu)) { | |
98 | return lttng_ust_get_cpu_internal(); | |
99 | } else { | |
100 | return getcpu(); | |
101 | } | |
102 | } | |
103 | ||
2b2d6ff7 | 104 | #endif /* _LTTNG_GETCPU_H */ |