1.\" $NetBSD: nanosleep.2,v 1.17 2015/10/02 19:52:49 christos Exp $ 2.\" 3.\" Copyright (c) 1986, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)sleep.3 8.1 (Berkeley) 6/4/93 31.\" 32.Dd October 2, 2015 33.Dt NANOSLEEP 2 34.Os 35.Sh NAME 36.Nm nanosleep 37.Nd high resolution sleep 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In time.h 42.Ft int 43.Fn clock_nanosleep "clockid_t clock_id" "int flags" "const struct timespec *rqtp" "struct timespec *rmtp" 44.Ft int 45.Fn nanosleep "const struct timespec *rqtp" "struct timespec *rmtp" 46.Sh DESCRIPTION 47If the 48.Dv TIMER_ABSTIME 49flag is not set in the 50.Fa flags 51argument, then 52.Fn clock_nanosleep 53suspends execution of the calling thread until either the number of 54seconds and nanoseconds specified in the 55.Fa rqtp 56argument have elapsed using the clock in the 57.Fa clock_id 58argument, or a signal is delivered to the calling process and its 59action is to invoke a signal catching function or to terminate the 60process. 61.Pp 62If the 63.Dv TIMER_ABSTIME 64flag is set in the 65.Fa flags 66argument, then 67.Fn clock_nanosleep 68suspends execution of the calling thread until either the value 69of the clock specified in the 70.Fa clock_id 71argument reaches the value of the 72.Fa rqtp 73argument in seconds and nanoseconds, 74or a signal is delivered to the calling process and its 75action is to invoke a signal catching function or to terminate the 76process. 77.Pp 78The suspension time may be longer than requested due to the 79scheduling of other activity by the system. 80.Pp 81The 82.Fn nanosleep 83function behaves like 84.Fn clock_nanosleep 85with the 86.Fa clock_id 87argument equal to 88.Dv CLOCK_MONOTONIC 89and the 90.Fa flags 91argument having 92.Dv TIMER_ABSTIME 93not set. 94.Pp 95The 96.Em struct timespec 97is described in 98.Xr timespec 3 . 99The 100.Fa clock_id 101specified is the time source. 102.Sh RETURN VALUES 103If the 104.Fn clock_nanosleep 105or the 106.Fn nanosleep 107functions return because the requested time has elapsed, the value 108returned will be zero. 109.Pp 110If the 111.Fn clock_nanosleep 112or the 113.Fn nanosleep 114functions return due to the delivery of a signal, then 115.Fn clock_nanosleep 116will return directly the error number, and 117.Fn nanosleep 118will return \-1, and the global variable 119.Va errno 120will be set to indicate the interruption. 121If 122.Fa rmtp 123is 124.Pf non- Dv NULL , 125the timespec structure it references is updated to contain the 126unslept amount (the request time minus the time actually slept). 127.Sh ERRORS 128If any of the following conditions occur, the 129.Fn nanosleep 130function shall return \-1 and set 131.Va errno 132to the corresponding value, and the 133.Fn clock_nanosleep 134function shall return the errnor number directly. 135.Bl -tag -width Er 136.It Bq Er EFAULT 137Either 138.Fa rqtp 139or 140.Fa rmtp 141points to memory that is not a valid part of the process 142address space. 143.It Bq Er EINTR 144.Nm 145was interrupted by the delivery of a signal. 146.It Bq Er EINVAL 147.Fa rqtp 148specified a nanosecond value less than zero or greater than 1000 million. 149.It Bq Er ENOSYS 150.Nm 151is not supported by this implementation. 152.It Bq Er ENOTSUP 153for 154.Fn clock_nanosleep , 155the clock specified in the 156.Fa clock_id 157argument is not supported. 158.El 159.Sh SEE ALSO 160.Xr sleep 3 , 161.Xr timespec 3 162.Sh STANDARDS 163The 164.Fn nanosleep 165function conforms to 166.St -p1003.1b-93 . 167The 168.Fn clock_nanosleep 169function conforms to 170.St -p1003.1j-2000 . 171.Sh BUGS 172The 173.Nx 174kernel is not tickless, so the maximum sleep resolution is determined 175by the value of 176.Dv HZ 177which is by default 178.Dv 100 179in most architectures. 180This means that a request to sleep for less than 181.Dv 10ms 182(1 / 183.Dv HZ 184seconds), is rounded up to that. 185