CLOCK_GETCPUCLOCKID(3) - man page online | library functions

Obtain ID of a process CPU-time clock.

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


clock_getcpuclockid - obtain ID of a process CPU-time clock


#include <time.h> int clock_getcpuclockid(pid_t pid, clockid_t *clock_id); Link with -lrt (only for glibc versions before 2.17). Feature Test Macro Requirements for glibc (see feature_test_macros(7)): clock_getcpuclockid(): _XOPEN_SOURCE >= 600 || _POSIX_C_SOURCE >= 200112L


The clock_getcpuclockid() function obtains the ID of the CPU-time clock of the process whose ID is pid, and returns it in the location pointed to by clock_id. If pid is zero, then the clock ID of the CPU-time clock of the calling process is returned.


On success, clock_getcpuclockid() returns 0; on error, it returns one of the positive error numbers listed in ERRORS.


ENOSYS The kernel does not support obtaining the per-process CPU-time clock of another process, and pid does not specify the calling process. EPERM The caller does not have permission to access the CPU-time clock of the process specified by pid. (Specified in POSIX.1-2001; does not occur on Linux unless the kernel does not support obtaining the per-process CPU-time clock of another process.) ESRCH There is no process with the ID pid.


The clock_getcpuclockid() function is available in glibc since version 2.2.


For an explanation of the terms used in this section, see attributes(7). ┌──────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├──────────────────────┼───────────────┼─────────┤ │clock_getcpuclockid() │ Thread safety │ MT-Safe │ └──────────────────────┴───────────────┴─────────┘


POSIX.1-2001, POSIX.1-2008.


Calling clock_gettime(2) with the clock ID obtained by a call to clock_getcpuclockid() with a pid of 0, is the same as using the clock ID CLOCK_PROCESS_CPUTIME_ID.


The example program below obtains the CPU-time clock ID of the process whose ID is given on the command line, and then uses clock_gettime(2) to obtain the time on that clock. An example run is the following: $ ./a.out 1 # Show CPU clock of init process CPU-time clock for PID 1 is 2.213466748 seconds Program source #define _XOPEN_SOURCE 600 #include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <time.h> int main(int argc, char *argv[]) { clockid_t clockid; struct timespec ts; if (argc != 2) { fprintf(stderr, "%s <process-ID>\n", argv[0]); exit(EXIT_FAILURE); } if (clock_getcpuclockid(atoi(argv[1]), &clockid) != 0) { perror("clock_getcpuclockid"); exit(EXIT_FAILURE); } if (clock_gettime(clockid, &ts) == -1) { perror("clock_gettime"); exit(EXIT_FAILURE); } printf("CPU-time clock for PID %s is %ld.%09ld seconds\n", argv[1], (long) ts.tv_sec, (long) ts.tv_nsec); exit(EXIT_SUCCESS); }


clock_getres(2), timer_create(2), pthread_getcpuclockid(3), time(7)


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Linux 2015-08-08 CLOCK_GETCPUCLOCKID(3)
This manual Reference Other manuals
clock_getcpuclockid(3) referred by clock_getres(2) | clock_nanosleep(2) | pthread_getcpuclockid(3) | time(7) | timer_create(2)
refer to attributes(7) | clock_getres(2) | feature_test_macros(7) | pthread_getcpuclockid(3) | time(7) | timer_create(2)