1PTHREAD_GETCPUCLOCKID(3) Linux Programmer's Manual PTHREAD_GETCPUCLOCKID(3)
2
6 pthread_getcpuclockid - retrieve ID of a thread's CPU time clock
7
9 #include <pthread.h>
10 #include <time.h>
11 int pthread_getcpuclockid(pthread_t thread, clockid_t *clockid);
13 Compile and link with -pthread.
15
17 The pthread_getcpuclockid() function obtains the ID of the CPU-time
18 clock of the thread whose ID is given in thread, and returns it in the
19 location pointed to by clockid.
20
22 On success, this function returns 0; on error, it returns a nonzero er‐
23 ror number.
24
26 ENOENT Per-thread CPU time clocks are not supported by the system.
27 ESRCH No thread with the ID thread could be found.
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31 This function is available in glibc since version 2.2.
32
34 For an explanation of the terms used in this section, see at‐
35 tributes(7).
36 ┌────────────────────────────────────────────┬───────────────┬─────────┐
38 │Interface │ Attribute │ Value │
39 ├────────────────────────────────────────────┼───────────────┼─────────┤
40 │pthread_getcpuclockid() │ Thread safety │ MT-Safe │
41 └────────────────────────────────────────────┴───────────────┴─────────┘
42
44 POSIX.1-2001, POSIX.1-2008.
45
47 When thread refers to the calling thread, this function returns an
48 identifier that refers to the same clock manipulated by clock_get‐
49 time(2) and clock_settime(2) when given the clock ID
50 CLOCK_THREAD_CPUTIME_ID.
51
53 The program below creates a thread and then uses clock_gettime(2) to
54 retrieve the total process CPU time, and the per-thread CPU time con‐
55 sumed by the two threads. The following shell session shows an example
56 run:
57 $ ./a.out
59 Main thread sleeping
60 Subthread starting infinite loop
61 Main thread consuming some CPU time...
62 Process total CPU time: 1.368
63 Main thread CPU time: 0.376
64 Subthread CPU time: 0.992
65 Program source
67 /* Link with "-lrt" */
69 #include <time.h>
71 #include <stdio.h>
72 #include <stdint.h>
73 #include <stdlib.h>
74 #include <unistd.h>
75 #include <pthread.h>
76 #include <string.h>
77 #include <errno.h>
78 #define handle_error(msg) \
80 do { perror(msg); exit(EXIT_FAILURE); } while (0)
81 #define handle_error_en(en, msg) \
83 do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
84 static void *
86 thread_start(void *arg)
87 {
88 printf("Subthread starting infinite loop\n");
89 for (;;)
90 continue;
91 }
92 static void
94 pclock(char *msg, clockid_t cid)
95 {
96 struct timespec ts;
97 printf("%s", msg);
99 if (clock_gettime(cid, &ts) == -1)
100 handle_error("clock_gettime");
101 printf("%4jd.%03ld\n", (intmax_t) ts.tv_sec, ts.tv_nsec / 1000000);
102 }
103 int
105 main(int argc, char *argv[])
106 {
107 pthread_t thread;
108 clockid_t cid;
109 int s;
110 s = pthread_create(&thread, NULL, thread_start, NULL);
112 if (s != 0)
113 handle_error_en(s, "pthread_create");
114 printf("Main thread sleeping\n");
116 sleep(1);
117 printf("Main thread consuming some CPU time...\n");
119 for (int j = 0; j < 2000000; j++)
120 getppid();
121 pclock("Process total CPU time: ", CLOCK_PROCESS_CPUTIME_ID);
123 s = pthread_getcpuclockid(pthread_self(), &cid);
125 if (s != 0)
126 handle_error_en(s, "pthread_getcpuclockid");
127 pclock("Main thread CPU time: ", cid);
128 /* The preceding 4 lines of code could have been replaced by:
130 pclock("Main thread CPU time: ", CLOCK_THREAD_CPUTIME_ID); */
131 s = pthread_getcpuclockid(thread, &cid);
133 if (s != 0)
134 handle_error_en(s, "pthread_getcpuclockid");
135 pclock("Subthread CPU time: 1 ", cid);
136 exit(EXIT_SUCCESS); /* Terminates both threads */
138 }
139
141 clock_gettime(2), clock_settime(2), timer_create(2), clock_getcpu‐
142 clockid(3), pthread_self(3), pthreads(7), time(7)
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145 This page is part of release 5.13 of the Linux man-pages project. A
146 description of the project, information about reporting bugs, and the
147 latest version of this page, can be found at
148 https://www.kernel.org/doc/man-pages/.
149Linux 2021-03-22 PTHREAD_GETCPUCLOCKID(3)