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diff --git a/man2/nanosleep.2 b/man2/nanosleep.2 deleted file mode 100644 index 122419296..000000000 --- a/man2/nanosleep.2 +++ /dev/null @@ -1,220 +0,0 @@ -.\" Copyright (C) Markus Kuhn, 1996 -.\" and Copyright (C) Linux Foundation, 2008, written by Michael Kerrisk -.\" <mtk.manpages@gmail.com> -.\" -.\" SPDX-License-Identifier: GPL-2.0-or-later -.\" -.\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de> -.\" First version written -.\" Modified, 2004-10-24, aeb -.\" 2008-06-24, mtk -.\" Minor rewrites of some parts. -.\" NOTES: describe case where clock_nanosleep() can be preferable. -.\" NOTES: describe CLOCK_REALTIME versus CLOCK_NANOSLEEP -.\" Replace crufty discussion of HZ with a pointer to time(7). -.TH nanosleep 2 (date) "Linux man-pages (unreleased)" -.SH NAME -nanosleep \- high-resolution sleep -.SH LIBRARY -Standard C library -.RI ( libc ", " \-lc ) -.SH SYNOPSIS -.nf -.B #include <time.h> -.PP -.BI "int nanosleep(const struct timespec *" req , -.BI " struct timespec *_Nullable " rem ); -.fi -.PP -.RS -4 -Feature Test Macro Requirements for glibc (see -.BR feature_test_macros (7)): -.RE -.PP -.BR nanosleep (): -.nf - _POSIX_C_SOURCE >= 199309L -.fi -.SH DESCRIPTION -.BR nanosleep () -suspends the execution of the calling thread -until either at least the time specified in -.I *req -has elapsed, or the delivery of a signal -that triggers the invocation of a handler in the calling thread or -that terminates the process. -.PP -If the call is interrupted by a signal handler, -.BR nanosleep () -returns \-1, sets -.I errno -to -.BR EINTR , -and writes the remaining time into the structure pointed to by -.I rem -unless -.I rem -is NULL. -The value of -.I *rem -can then be used to call -.BR nanosleep () -again and complete the specified pause (but see NOTES). -.PP -The -.BR timespec (3) -structure -is used to specify intervals of time with nanosecond precision. -.PP -The value of the nanoseconds field must be in the range [0, 999999999]. -.PP -Compared to -.BR sleep (3) -and -.BR usleep (3), -.BR nanosleep () -has the following advantages: -it provides a higher resolution for specifying the sleep interval; -POSIX.1 explicitly specifies that it -does not interact with signals; -and it makes the task of resuming a sleep that has been -interrupted by a signal handler easier. -.SH RETURN VALUE -On successfully sleeping for the requested interval, -.BR nanosleep () -returns 0. -If the call is interrupted by a signal handler or encounters an error, -then it returns \-1, with -.I errno -set to indicate the error. -.SH ERRORS -.TP -.B EFAULT -Problem with copying information from user space. -.TP -.B EINTR -The pause has been interrupted by a signal that was -delivered to the thread (see -.BR signal (7)). -The remaining sleep time has been written -into -.I *rem -so that the thread can easily call -.BR nanosleep () -again and continue with the pause. -.TP -.B EINVAL -The value in the -.I tv_nsec -field was not in the range [0, 999999999] or -.I tv_sec -was negative. -.SH VERSIONS -POSIX.1 specifies that -.BR nanosleep () -should measure time against the -.B CLOCK_REALTIME -clock. -However, Linux measures the time using the -.B CLOCK_MONOTONIC -clock. -.\" See also http://thread.gmane.org/gmane.linux.kernel/696854/ -.\" Subject: nanosleep() uses CLOCK_MONOTONIC, should be CLOCK_REALTIME? -.\" Date: 2008-06-22 07:35:41 GMT -This probably does not matter, since the POSIX.1 specification for -.BR clock_settime (2) -says that discontinuous changes in -.B CLOCK_REALTIME -should not affect -.BR nanosleep (): -.RS -.PP -Setting the value of the -.B CLOCK_REALTIME -clock via -.BR clock_settime (2) -shall -have no effect on threads that are blocked waiting for a relative time -service based upon this clock, including the -.BR nanosleep () -function; ... -Consequently, these time services shall expire when the requested relative -interval elapses, independently of the new or old value of the clock. -.RE -.SH STANDARDS -POSIX.1-2008. -.SH HISTORY -POSIX.1-2001. -.PP -In order to support applications requiring much more precise pauses -(e.g., in order to control some time-critical hardware), -.BR nanosleep () -would handle pauses of up to 2 milliseconds by busy waiting with microsecond -precision when called from a thread scheduled under a real-time policy -like -.B SCHED_FIFO -or -.BR SCHED_RR . -This special extension was removed in Linux 2.5.39, -and is thus not available in Linux 2.6.0 and later kernels. -.SH NOTES -If the interval specified in -.I req -is not an exact multiple of the granularity underlying clock (see -.BR time (7)), -then the interval will be rounded up to the next multiple. -Furthermore, after the sleep completes, there may still be a delay before -the CPU becomes free to once again execute the calling thread. -.PP -The fact that -.BR nanosleep () -sleeps for a relative interval can be problematic if the call -is repeatedly restarted after being interrupted by signals, -since the time between the interruptions and restarts of the call -will lead to drift in the time when the sleep finally completes. -This problem can be avoided by using -.BR clock_nanosleep (2) -with an absolute time value. -.SH BUGS -If a program that catches signals and uses -.BR nanosleep () -receives signals at a very high rate, -then scheduling delays and rounding errors in the kernel's -calculation of the sleep interval and the returned -.I remain -value mean that the -.I remain -value may steadily -.I increase -on successive restarts of the -.BR nanosleep () -call. -To avoid such problems, use -.BR clock_nanosleep (2) -with the -.B TIMER_ABSTIME -flag to sleep to an absolute deadline. -.PP -In Linux 2.4, if -.BR nanosleep () -is stopped by a signal (e.g., -.BR SIGTSTP ), -then the call fails with the error -.B EINTR -after the thread is resumed by a -.B SIGCONT -signal. -If the system call is subsequently restarted, -then the time that the thread spent in the stopped state is -.I not -counted against the sleep interval. -This problem is fixed in Linux 2.6.0 and later kernels. -.SH SEE ALSO -.BR clock_nanosleep (2), -.BR restart_syscall (2), -.BR sched_setscheduler (2), -.BR timer_create (2), -.BR sleep (3), -.BR timespec (3), -.BR usleep (3), -.BR time (7) |