1PTHREAD_GETCPUCLOCKID(3) Linux Programmer's Manual PTHREAD_GETCPUCLOCKID(3)
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6 pthread_getcpuclockid - retrieve ID of a thread's CPU time clock
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9 #include <pthread.h>
10 #include <time.h>
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12 int pthread_getcpuclockid(pthread_t thread, clockid_t *clock_id);
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14 Compile and link with -pthread.
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17 The pthread_getcpuclockid() function returns the clock ID for the CPU
18 time clock of the thread thread.
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21 On success, this function returns 0; on error, it returns a nonzero
22 error number.
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25 ENOENT Per-thread CPU time clocks are not supported by the system.
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27 ESRCH No thread with the ID thread could be found.
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30 This function is available in glibc since version 2.2.
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33 For an explanation of the terms used in this section, see
34 attributes(7).
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36 ┌────────────────────────┬───────────────┬─────────┐
37 │Interface │ Attribute │ Value │
38 ├────────────────────────┼───────────────┼─────────┤
39 │pthread_getcpuclockid() │ Thread safety │ MT-Safe │
40 └────────────────────────┴───────────────┴─────────┘
42 POSIX.1-2001, POSIX.1-2008.
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45 When thread refers to the calling thread, this function returns an
46 identifier that refers to the same clock manipulated by clock_get‐
47 time(2) and clock_settime(2) when given the clock ID
48 CLOCK_THREAD_CPUTIME_ID.
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51 The program below creates a thread and then uses clock_gettime(2) to
52 retrieve the total process CPU time, and the per-thread CPU time con‐
53 sumed by the two threads. The following shell session shows an example
54 run:
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56 $ ./a.out
57 Main thread sleeping
58 Subthread starting infinite loop
59 Main thread consuming some CPU time...
60 Process total CPU time: 1.368
61 Main thread CPU time: 0.376
62 Subthread CPU time: 0.992
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64 Program source
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66 /* Link with "-lrt" */
67
68 #include <time.h>
69 #include <stdio.h>
70 #include <stdlib.h>
71 #include <unistd.h>
72 #include <pthread.h>
73 #include <string.h>
74 #include <errno.h>
75
76 #define handle_error(msg) \
77 do { perror(msg); exit(EXIT_FAILURE); } while (0)
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79 #define handle_error_en(en, msg) \
80 do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
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82 static void *
83 thread_start(void *arg)
84 {
85 printf("Subthread starting infinite loop\n");
86 for (;;)
87 continue;
88 }
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90 static void
91 pclock(char *msg, clockid_t cid)
92 {
93 struct timespec ts;
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95 printf("%s", msg);
96 if (clock_gettime(cid, &ts) == -1)
97 handle_error("clock_gettime");
98 printf("%4ld.%03ld\n", ts.tv_sec, ts.tv_nsec / 1000000);
99 }
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101 int
102 main(int argc, char *argv[])
103 {
104 pthread_t thread;
105 clockid_t cid;
106 int j, s;
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108 s = pthread_create(&thread, NULL, thread_start, NULL);
109 if (s != 0)
110 handle_error_en(s, "pthread_create");
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112 printf("Main thread sleeping\n");
113 sleep(1);
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115 printf("Main thread consuming some CPU time...\n");
116 for (j = 0; j < 2000000; j++)
117 getppid();
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119 pclock("Process total CPU time: ", CLOCK_PROCESS_CPUTIME_ID);
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121 s = pthread_getcpuclockid(pthread_self(), &cid);
122 if (s != 0)
123 handle_error_en(s, "pthread_getcpuclockid");
124 pclock("Main thread CPU time: ", cid);
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126 /* The preceding 4 lines of code could have been replaced by:
127 pclock("Main thread CPU time: ", CLOCK_THREAD_CPUTIME_ID); */
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129 s = pthread_getcpuclockid(thread, &cid);
130 if (s != 0)
131 handle_error_en(s, "pthread_getcpuclockid");
132 pclock("Subthread CPU time: 1 ", cid);
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134 exit(EXIT_SUCCESS); /* Terminates both threads */
135 }
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138 clock_gettime(2), clock_settime(2), timer_create(2), clock_getcpu‐
139 clockid(3), pthread_self(3), pthreads(7), time(7)
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142 This page is part of release 5.02 of the Linux man-pages project. A
143 description of the project, information about reporting bugs, and the
144 latest version of this page, can be found at
145 https://www.kernel.org/doc/man-pages/.
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149Linux 2019-03-06 PTHREAD_GETCPUCLOCKID(3)