pthread_getcpuclockid(3)

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
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SYNOPSIS

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

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.
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RETURN VALUE

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

26       ENOENT Per-thread CPU time clocks are not supported by the system.
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28       ESRCH  No thread with the ID thread could be found.
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VERSIONS

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

34       For  an  explanation  of  the  terms  used   in   this   section,   see
35       attributes(7).
36
37       ┌────────────────────────┬───────────────┬─────────┐
38       │Interface               │ Attribute     │ Value   │
39       ├────────────────────────┼───────────────┼─────────┤
40       │pthread_getcpuclockid() │ Thread safety │ MT-Safe │
41       └────────────────────────┴───────────────┴─────────┘

CONFORMING TO

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

46       When  thread  refers  to  the  calling thread, this function returns an
47       identifier that refers to the  same  clock  manipulated  by  clock_get‐
48       time(2)    and    clock_settime(2)    when    given    the   clock   ID
49       CLOCK_THREAD_CPUTIME_ID.
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EXAMPLES

52       The program below creates a thread and then  uses  clock_gettime(2)  to
53       retrieve  the  total process CPU time, and the per-thread CPU time con‐
54       sumed by the two threads.  The following shell session shows an example
55       run:
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57           $ ./a.out
58           Main thread sleeping
59           Subthread starting infinite loop
60           Main thread consuming some CPU time...
61           Process total CPU time:    1.368
62           Main thread CPU time:      0.376
63           Subthread CPU time:        0.992
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65   Program source
66
67       /* Link with "-lrt" */
68
69       #include <time.h>
70       #include <stdio.h>
71       #include <stdlib.h>
72       #include <unistd.h>
73       #include <pthread.h>
74       #include <string.h>
75       #include <errno.h>
76
77       #define handle_error(msg) \
78               do { perror(msg); exit(EXIT_FAILURE); } while (0)
79
80       #define handle_error_en(en, msg) \
81               do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
82
83       static void *
84       thread_start(void *arg)
85       {
86           printf("Subthread starting infinite loop\n");
87           for (;;)
88               continue;
89       }
90
91       static void
92       pclock(char *msg, clockid_t cid)
93       {
94           struct timespec ts;
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96           printf("%s", msg);
97           if (clock_gettime(cid, &ts) == -1)
98               handle_error("clock_gettime");
99           printf("%4ld.%03ld\n", ts.tv_sec, ts.tv_nsec / 1000000);
100       }
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102       int
103       main(int argc, char *argv[])
104       {
105           pthread_t thread;
106           clockid_t cid;
107           int j, s;
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109           s = pthread_create(&thread, NULL, thread_start, NULL);
110           if (s != 0)
111               handle_error_en(s, "pthread_create");
112
113           printf("Main thread sleeping\n");
114           sleep(1);
115
116           printf("Main thread consuming some CPU time...\n");
117           for (j = 0; j < 2000000; j++)
118               getppid();
119
120           pclock("Process total CPU time: ", CLOCK_PROCESS_CPUTIME_ID);
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122           s = pthread_getcpuclockid(pthread_self(), &cid);
123           if (s != 0)
124               handle_error_en(s, "pthread_getcpuclockid");
125           pclock("Main thread CPU time:   ", cid);
126
127           /* The preceding 4 lines of code could have been replaced by:
128              pclock("Main thread CPU time:   ", CLOCK_THREAD_CPUTIME_ID); */
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130           s = pthread_getcpuclockid(thread, &cid);
131           if (s != 0)
132               handle_error_en(s, "pthread_getcpuclockid");
133           pclock("Subthread CPU time: 1    ", cid);
134
135           exit(EXIT_SUCCESS);         /* Terminates both threads */
136       }
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COLOPHON

143       This page is part of release 5.07 of the Linux  man-pages  project.   A
144       description  of  the project, information about reporting bugs, and the
145       latest    version    of    this    page,    can     be     found     at
146       https://www.kernel.org/doc/man-pages/.
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150Linux                             2020-06-09          PTHREAD_GETCPUCLOCKID(3)