1PTHREAD_GETCPUCLOCKID(3)   Linux Programmer's Manual  PTHREAD_GETCPUCLOCKID(3)
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NAME

6       pthread_getcpuclockid - retrieve ID of a thread's CPU time clock
7

SYNOPSIS

9       #include <pthread.h>
10       #include <time.h>
11
12       int pthread_getcpuclockid(pthread_t thread, clockid_t *clock_id);
13
14       Compile and link with -pthread.
15

DESCRIPTION

17       The  pthread_getcpuclockid()  function returns the clock ID for the CPU
18       time clock of the thread thread.
19

RETURN VALUE

21       On success, this function returns 0; on error,  it  returns  a  nonzero
22       error number.
23

ERRORS

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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VERSIONS

30       This function is available in glibc since version 2.2.
31

ATTRIBUTES

33       For   an   explanation   of   the  terms  used  in  this  section,  see
34       attributes(7).
35
36       ┌────────────────────────┬───────────────┬─────────┐
37Interface               Attribute     Value   
38       ├────────────────────────┼───────────────┼─────────┤
39pthread_getcpuclockid() │ Thread safety │ MT-Safe │
40       └────────────────────────┴───────────────┴─────────┘

CONFORMING TO

42       POSIX.1-2001, POSIX.1-2008.
43

NOTES

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.
49

EXAMPLE

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:
55
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
63
64   Program source
65
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)
78
79       #define handle_error_en(en, msg) \
80               do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
81
82       static void *
83       thread_start(void *arg)
84       {
85           printf("Subthread starting infinite loop\n");
86           for (;;)
87               continue;
88       }
89
90       static void
91       pclock(char *msg, clockid_t cid)
92       {
93           struct timespec ts;
94
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       }
100
101       int
102       main(int argc, char *argv[])
103       {
104           pthread_t thread;
105           clockid_t cid;
106           int j, s;
107
108           s = pthread_create(&thread, NULL, thread_start, NULL);
109           if (s != 0)
110               handle_error_en(s, "pthread_create");
111
112           printf("Main thread sleeping\n");
113           sleep(1);
114
115           printf("Main thread consuming some CPU time...\n");
116           for (j = 0; j < 2000000; j++)
117               getppid();
118
119           pclock("Process total CPU time: ", CLOCK_PROCESS_CPUTIME_ID);
120
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);
125
126           /* The preceding 4 lines of code could have been replaced by:
127              pclock("Main thread CPU time:   ", CLOCK_THREAD_CPUTIME_ID); */
128
129           s = pthread_getcpuclockid(thread, &cid);
130           if (s != 0)
131               handle_error_en(s, "pthread_getcpuclockid");
132           pclock("Subthread CPU time: 1    ", cid);
133
134           exit(EXIT_SUCCESS);         /* Terminates both threads */
135       }
136

SEE ALSO

138       clock_gettime(2),  clock_settime(2),   timer_create(2),   clock_getcpu‐
139       clockid(3), pthread_self(3), pthreads(7), time(7)
140

COLOPHON

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)
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