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Diffstat (limited to 'man3/clock_getcpuclockid.3')
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diff --git a/man3/clock_getcpuclockid.3 b/man3/clock_getcpuclockid.3 new file mode 100644 index 0000000..749fdbe --- /dev/null +++ b/man3/clock_getcpuclockid.3 @@ -0,0 +1,156 @@ +'\" t +.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk +.\" <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH clock_getcpuclockid 3 2023-07-20 "Linux man-pages 6.05.01" +.SH NAME +clock_getcpuclockid \- obtain ID of a process CPU-time clock +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ), +since glibc 2.17 +.PP +Before glibc 2.17, +Real-time library +.RI ( librt ", " \-lrt ) +.SH SYNOPSIS +.B #include <time.h> +.nf +.PP +.BI "int clock_getcpuclockid(pid_t " pid ", clockid_t *" clockid ); +.fi +.PP +.ad l +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.PP +.BR clock_getcpuclockid (): +.nf + _POSIX_C_SOURCE >= 200112L +.fi +.SH DESCRIPTION +The +.BR clock_getcpuclockid () +function obtains the ID of the CPU-time clock of the process whose ID is +.IR pid , +and returns it in the location pointed to by +.IR clockid . +If +.I pid +is zero, then the clock ID of the CPU-time clock +of the calling process is returned. +.SH RETURN VALUE +On success, +.BR clock_getcpuclockid () +returns 0; +on error, it returns one of the positive error numbers listed in ERRORS. +.SH ERRORS +.TP +.B ENOSYS +The kernel does not support obtaining the per-process +CPU-time clock of another process, and +.I pid +does not specify the calling process. +.TP +.B EPERM +The caller does not have permission to access +the CPU-time clock of the process specified by +.IR 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.) +.TP +.B ESRCH +There is no process with the ID +.IR pid . +.SH ATTRIBUTES +For an explanation of the terms used in this section, see +.BR attributes (7). +.TS +allbox; +lbx lb lb +l l l. +Interface Attribute Value +T{ +.na +.nh +.BR clock_getcpuclockid () +T} Thread safety MT-Safe +.TE +.sp 1 +.SH STANDARDS +POSIX.1-2008. +.SH HISTORY +glibc 2.2. +POSIX.1-2001. +.SH NOTES +Calling +.BR clock_gettime (2) +with the clock ID obtained by a call to +.BR clock_getcpuclockid () +with a +.I pid +of 0, +is the same as using the clock ID +.BR CLOCK_PROCESS_CPUTIME_ID . +.SH EXAMPLES +The example program below obtains the +CPU-time clock ID of the process whose ID is given on the command line, +and then uses +.BR clock_gettime (2) +to obtain the time on that clock. +An example run is the following: +.PP +.in +4n +.EX +.RB "$" " ./a.out 1" " # Show CPU clock of init process" +CPU\-time clock for PID 1 is 2.213466748 seconds +.EE +.in +.SS Program source +\& +.\" SRC BEGIN (clock_getcpuclockid.c) +.EX +#define _XOPEN_SOURCE 600 +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <time.h> +#include <unistd.h> +\& +int +main(int argc, char *argv[]) +{ + clockid_t clockid; + struct timespec ts; +\& + if (argc != 2) { + fprintf(stderr, "%s <process\-ID>\en", 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 %jd.%09ld seconds\en", + argv[1], (intmax_t) ts.tv_sec, ts.tv_nsec); + exit(EXIT_SUCCESS); +} +.EE +.\" SRC END +.SH SEE ALSO +.BR clock_getres (2), +.BR timer_create (2), +.BR pthread_getcpuclockid (3), +.BR time (7) |