PTHREADGETCPUCLOCKID(3) Linux Programmer's Manual PTHREADGETCPUCLOCKID(3)

NAME
       pthreadgetcpuclockid - retrieve ID of a thread's CPU time clock

SYNOPSIS
       #include 
       #include 

       int pthreadgetcpuclockid(pthreadt thread, clockidt *clockid);

       Compile and link with -pthread.

DESCRIPTION
       The  pthreadgetcpuclockid()  function returns the clock ID for the CPU
       time clock of the thread thread.

RETURN VALUE
       On success, this function returns 0; on error,  it  returns  a  nonzero
       error number.

ERRORS
       ENOENT Per-thread CPU time clocks are not supported by the system.

       ESRCH  No thread with the ID thread could be found.

VERSIONS
       This function is available in glibc since version 2.2.

ATTRIBUTES
       For   an   explanation   of   the  terms  used  in  this  section,  see
       attributes(7).

       ┌────────────────────────┬───────────────┬─────────┐
       │Interface               │ Attribute     │ Value   │
       ├────────────────────────┼───────────────┼─────────┤
       │pthreadgetcpuclockid() │ Thread safety │ MT-Safe │
       └────────────────────────┴───────────────┴─────────┘
CONFORMING TO
       POSIX.1-2001.

NOTES
       When thread refers to the calling  thread,  this  function  returns  an
       identifier  that  refers  to  the  same clock manipulated by clockget‐
       time(2)   and   clocksettime(2)    when    given    the    clock    ID
       CLOCKTHREADCPUTIMEID.

EXAMPLE
       The  program  below  creates a thread and then uses clockgettime(2) to
       retrieve the total process CPU time, and the per-thread CPU  time  con‐
       sumed by the two threads.  The following shell session shows an example
       run:
           $ ./a.out
           Main thread sleeping
           Subthread starting infinite loop
           Main thread consuming some CPU time...
           Process total CPU time:    1.368
           Main thread CPU time:      0.376
           Subthread CPU time:        0.992

   Program source

       /* Link with "-lrt" */

       #include 
       #include 
       #include 
       #include 
       #include 
       #include 
       #include 

       #define handleerror(msg) \
               do { perror(msg); exit(EXITFAILURE); } while (0)

       #define handleerroren(en, msg) \
               do { errno = en; perror(msg); exit(EXITFAILURE); } while (0)

       static void *
       threadstart(void *arg)
       {
           printf("Subthread starting infinite loop\n");
           for (;;)
               continue;
       }

       static void
       pclock(char *msg, clockidt cid)
       {
           struct timespec ts;

           printf("%s", msg);
           if (clockgettime(cid, &ts) == -1)
               handleerror("clockgettime");
           printf("%4ld.%03ld\n", ts.tvsec, ts.tvnsec / 1000000);
       }

       int
       main(int argc, char *argv[])
       {
           pthreadt thread;
           clockidt cid;
           int j, s;

           s = pthreadcreate(&thread, NULL, threadstart, NULL);
           if (s != 0)
               handleerroren(s, "pthreadcreate");

           printf("Main thread sleeping\n");
           sleep(1);

           printf("Main thread consuming some CPU time...\n");
           for (j = 0; j < 2000000; j++)
               getppid();

           pclock("Process total CPU time: ", CLOCKPROCESSCPUTIMEID);

           s = pthreadgetcpuclockid(pthreadself(), &cid);
           if (s != 0)
               handleerroren(s, "pthreadgetcpuclockid");
           pclock("Main thread CPU time:   ", cid);

           /* The preceding 4 lines of code could have been replaced by:
              pclock("Main thread CPU time:   ", CLOCKTHREADCPUTIMEID); */

           s = pthreadgetcpuclockid(thread, &cid);
           if (s != 0)
               handleerroren(s, "pthreadgetcpuclockid");
           pclock("Subthread CPU time: 1    ", cid);

           exit(EXITSUCCESS);         /* Terminates both threads */
       }

SEE ALSO
       clockgettime(2),  clocksettime(2),   timercreate(2),   clockgetcpu‐
       clockid(3), pthreadself(3), pthreads(7), time(7)

COLOPHON
       This  page  is  part of release 3.53 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.



Linux                             2009-02-08          PTHREADGETCPUCLOCKID(3)