개요

• 솔라나라에 설명된 어플리케이션에 대해 맨 페이지를 찾아 출력한다.
• MAN 페이지에 대한 설명은 윈디하나의 솔라나라: MAN 페이지을 참고하자.
• svcadm(1M)을 검색하려면 섹션에서 1M 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.

get_sec_fromepoch(3c)

Standard C Library Functions                                    get_hrusec(3C)



NAME
       get_hrusec,   get_sec_fromepoch,  get_nsec_fromepoch  -  timestamp  for
       interval measurements

SYNOPSIS
       #include <sys/types.h>
       #include <sys/system_stats.h>

       void get_hrusec(hrtime_t *usec);

       void get_sec_fromepoch(memtime_sec_t *sec);

       void get_nsec_fromepoch(hrtime_t *nsec);

DESCRIPTION
       These functions are provided for performance reasons. The  overhead  of
       reading  time using these functions is minimum as they return time read
       from memory. No system calls are involved in get_* functions.


       The get_hrusec() function returns high-resolution real  time  which  is
       expressed  as microseconds since some arbitrary time in the past. It is
       not correlated in any way to the time of day, and thus is  not  subject
       to resetting or drifting by way of adjtime(2) or settimeofday(3C). This
       high-resolution time is suited for  performance  measurement.  Although
       the best time accuracy it gives is 1 millisecond unlike gethrtime(3C).


       The  get_sec_fromepoch() and get_nsec_fromepoch() functions return time
       expressed in elapsed seconds from epoch(January 1,  1970)  and  elapsed
       nanoseconds  from epoch respectively. Time returned by both these func‐
       tions are subject to setting or drifting by  adjtime(2)  or  settimeof‐
       day(3C)   calls.   Note   that   the  accuracy  of  nsecs  returned  by
       get_nsec_fromepoch() is 1 millisecond.


       The in memory time that is read by these functions, is  updated  by  an
       interrupt routine and so there will be slight variation compared to the
       time reported  by  the  gettimeofday()  function.  Therefore  the  time
       returned  by the get_sec_fromepoch() and get_nsec_fromepoch() functions
       should not be compared against  time  returned  by  the  gettimeofday()
       function.    For    more   information,   see   the   gettimeofday(3C),
       get_sec_fromepoch(3C) and get_nsec_fromepoch(3C) man pages.

EXAMPLES
       Example 1 Timestamping using get_hrusec(),
                 get_sec_fromepoch(), and
               get_nsec_fromepoch():



         #include <stdio.h>
         #include <unistd.h>
         #include <sys/system_stats.h>
         #include <time.h>

         void main() {
                 hrtime_t hres1, hres2;
                 memtime_sec_t   sec;

                 get_hrusec(&hres1);
                 sleep(1);
                 get_hrusec(&hres2);

                 printf("Slept for %lld microseconds\n",
                     (hres2 - hres1));

                 get_sec_fromepoch(&sec);
                 printf("Current time in seconds : %lld\n",
                     sec);

                 get_nsec_fromepoch(&hres1);
                 printf("Current time in nanoseconds: %lld\n",
                     hres1);
         }



ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE  TYPEAT‐
       TRIBUTE VALUE _ Architecture SPARC and x86 _ Interface StabilityCommit‐
       ted _ MT-LevelMT-Safe


SEE ALSO
       gettimeofday(3C), gethrtime(3C)



Oracle Solaris 11.4               31 Aug 2016                   get_hrusec(3C)