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.\" Copyright (C) Tom Bjorkholm & Markus Kuhn, 1996
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.\" 1996-04-01 Tom Bjorkholm <tomb@mydata.se>
.\"            First version written
.\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
.\"            revision
.\"
.TH RR_GET_INTERVAL 2 1996-04-10 "Linux 1.3.81" "Linux Programmer's Manual"
.SH NAME
sched_rr_get_interval  \- get the SCHED_RR interval for the named process
.SH SYNOPSIS
.B #include <sched.h>
.sp
\fBint sched_rr_get_interval(pid_t \fIpid\fB, struct timespec *\fItp\fB);
.sp
.nf
.ta 4n 12n 24n
\fBstruct timespec {
	time_t	tv_sec;	/* seconds */
	long	tv_nsec;	/* nanoseconds */
};
.ta
.fi
.SH DESCRIPTION
.BR sched_rr_get_interval ()
writes into the \fItimespec\fR structure pointed to by \fItp\fR the
round robin time quantum for the process identified by \fIpid\fR. If
\fIpid\fR is zero, the time quantum for the calling process is written
into *\fItp\fR. The identified process should be running under the
.I SCHED_RR 
scheduling policy.

The round robin time quantum value is not alterable under Linux
1.3.81.

POSIX systems on which
.BR sched_rr_get_interval ()
is available define
.I _POSIX_PRIORITY_SCHEDULING
in <unistd.h>.
.SH "RETURN VALUE"
On success,
.BR sched_rr_get_interval ()
returns 0.
On error, \-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
.TP
.B EFAULT
Problem with copying information to userspace.
.TP
.B EINVAL
Invalid pid.
.TP
.B ENOSYS
The system call is not yet implemented.
.TP
.B ESRCH
The process whose ID is \fIpid\fR could not be found.
.SH "CONFORMING TO"
POSIX.1-2001.
.SH BUGS
As of Linux 1.3.81 \fBsched_rr_get_interval\fR() returns with error
ENOSYS, because SCHED_RR has not yet been fully implemented and tested
properly.
.SH "SEE ALSO"
.BR sched_setscheduler (2)
has a description of the Linux scheduling scheme.
.PP
.I Programming for the real world \- POSIX.4
by Bill O. Gallmeister, O'Reilly & Associates, Inc., ISBN 1-56592-074-0