sleep 함수들

$ man -k sleep Time::HiRes          (3pm)  - High resolution alarm, sleep, gettimeofday, interval timers apmsleep             (1)  - go into suspend or standby mode and wake-up later clock_nanosleep      (2)  - Suspend execution of the currently running thread clock_nanosleep      (3p)  - high resolution sleep with specifiable clock (ADVANCED REALTIME) nanosleep            (2)  - pause execution for a specified time nanosleep            (3p)  - high resolution sleep (REALTIME) sleep                (1)  - delay for a specified amount of time sleep                (1p)  - suspend execution for an interval sleep                (3)  - Sleep for the specified number of seconds sleep                (3p)  - suspend execution for an interval of time usleep               (1)  - sleep some number of microseconds usleep               (3)  - suspend execution for microsecond intervals usleep               (3p)  - suspend execution for an interval

usleep은 1초 까지만 잠재울수 있는 제약이 있다.(1,000,000usec = 1,000msec = 1sec)

USLEEP(P)                  POSIX Programmer’s Manual                 USLEEP(P) NAME        usleep - suspend execution for an interval SYNOPSIS        #include <unistd.h>        int usleep(useconds_t useconds); DESCRIPTION        The  usleep()  function  shall cause the calling thread to be suspended from execution until either the number of        realtime microseconds specified by the argument useconds has elapsed or a signal  is  delivered  to  the  calling        thread  and  its action is to invoke a signal-catching function or to terminate the process.  The suspension time        may be longer than requested due to the scheduling of other activity by the system.        The useconds argument shall be less than one million. If the value of useconds is 0, then the call has no effect.

sleep은 1초 단위로 무제한으로 쓸수 있다.(실질적인 제약은 시스템에 따라 다르지만 32bit / 64bit unsigned int)

SLEEP(P)                   POSIX Programmer’s Manual                  SLEEP(P) NAME        sleep - suspend execution for an interval of time SYNOPSIS        #include <unistd.h>        unsigned sleep(unsigned seconds); DESCRIPTION        The  sleep() function shall cause the calling thread to be suspended from execution until either the number of        realtime seconds specified by the argument seconds has elapsed or a signal is delivered to the calling  thread        and its action is to invoke a signal-catching function or to terminate the process. The suspension time may be        longer than requested due to the scheduling of other activity by the system.        If a SIGALRM signal is generated for the calling process during execution of sleep() and if the SIGALRM signal        is  being  ignored or blocked from delivery, it is unspecified whether sleep() returns when the SIGALRM signal        is scheduled. If the signal is being blocked, it is also unspecified whether it remains pending after  sleep()        returns or it is discarded.

nanosleep은 REALTIME 확장인 듯 한데.. 먼지 모르겠다 ㄱ-
일단은 위의 sleep, usleep과는 다르게 include 파일이 다르다.

NANOSLEEP(P)               POSIX Programmer’s Manual              NANOSLEEP(P) NAME        nanosleep - high resolution sleep (REALTIME) SYNOPSIS        #include <time.h>        int nanosleep(const struct timespec *rqtp, struct timespec *rmtp); DESCRIPTION        The  nanosleep()  function shall cause the current thread to be suspended from execution until either the time        interval specified by the rqtp argument has elapsed or a signal is delivered to the calling  thread,  and  its        action  is to invoke a signal-catching function or to terminate the process. The suspension time may be longer        than requested because the argument value is rounded up to an integer multiple  of  the  sleep  resolution  or        because  of the scheduling of other activity by the system. But, except for the case of being interrupted by a        signal, the suspension time shall not be less than the time specified by rqtp, as measured by the system clock        CLOCK_REALTIME.        The use of the nanosleep() function has no effect on the action or blockage of any signal.