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 *clock_id);
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14       Compile and link with -pthread.
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DESCRIPTION

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

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

33       POSIX.1-2001.
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NOTES

36       When  thread  refers  to  the  calling thread, this function returns an
37       identifier that refers to the  same  clock  manipulated  by  clock_get‐
38       time(2)    and    clock_settime(2)    when    given    the   clock   ID
39       CLOCK_THREAD_CPUTIME_ID.
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EXAMPLE

42       The program below creates a thread and then  uses  clock_gettime(2)  to
43       retrieve  the  total process CPU time, and the per-thread CPU time con‐
44       sumed by the two threads.  The following shell session shows an example
45       run:
46           $ ./a.out
47           Main thread sleeping
48           Subthread starting infinite loop
49           Main thread consuming some CPU time...
50           Process total CPU time:    1.368
51           Main thread CPU time:      0.376
52           Subthread CPU time:        0.992
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54   Program source
55
56       /* Link with "-lrt" */
57
58       #include <time.h>
59       #include <stdio.h>
60       #include <stdlib.h>
61       #include <unistd.h>
62       #include <pthread.h>
63       #include <string.h>
64       #include <errno.h>
65
66       #define handle_error(msg) \
67               do { perror(msg); exit(EXIT_FAILURE); } while (0)
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69       #define handle_error_en(en, msg) \
70               do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
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72       static void *
73       thread_start(void *arg)
74       {
75           printf("Subthread starting infinite loop\n");
76           for (;;)
77               continue;
78       }
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80       static void
81       pclock(char *msg, clockid_t cid)
82       {
83           struct timespec ts;
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85           printf("%s", msg);
86           if (clock_gettime(cid, &ts) == -1)
87               handle_error("clock_gettime");
88           printf("%4ld.%03ld\n", ts.tv_sec, ts.tv_nsec / 1000000);
89       }
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91       int
92       main(int argc, char *argv[])
93       {
94           pthread_t thread;
95           clockid_t cid;
96           int j, s;
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98           s = pthread_create(&thread, NULL, thread_start, NULL);
99           if (s != 0)
100               handle_error_en(s, "pthread_create");
101
102           printf("Main thread sleeping\n");
103           sleep(1);
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105           printf("Main thread consuming some CPU time...\n");
106           for (j = 0; j < 2000000; j++)
107               getppid();
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109           pclock("Process total CPU time: ", CLOCK_PROCESS_CPUTIME_ID);
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111           s = pthread_getcpuclockid(pthread_self(), &cid);
112           if (s != 0)
113               handle_error_en(s, "pthread_getcpuclockid");
114           pclock("Main thread CPU time:   ", cid);
115
116           /* The preceding 4 lines of code could have been replaced by:
117              pclock("Main thread CPU time:   ", CLOCK_THREAD_CPUTIME_ID); */
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119           s = pthread_getcpuclockid(thread, &cid);
120           if (s != 0)
121               handle_error_en(s, "pthread_getcpuclockid");
122           pclock("Subthread CPU time: 1    ", cid);
123
124           exit(EXIT_SUCCESS);         /* Terminates both threads */
125       }
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COLOPHON

132       This page is part of release 3.25 of the Linux  man-pages  project.   A
133       description  of  the project, and information about reporting bugs, can
134       be found at http://www.kernel.org/doc/man-pages/.
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138Linux                             2009-02-08          PTHREAD_GETCPUCLOCKID(3)