freebsd-dev/lib/libc/sys/sched_get_priority_max.2

.\" $FreeBSD$
.\" Copyright (c) 1998 HD Associates, Inc.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.Dd March 12, 1998
.Dt SCHED_GET_PRIORITY_MAX 2
.Os
.Sh NAME
.Nm sched_get_priority_max ,
.Nm sched_get_priority_min ,
.Nm sched_rr_get_interval
.Nd get scheduling parameter limits
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sched.h
.Ft int
.Fn sched_get_priority_max "int policy"
.Ft int
.Fn sched_get_priority_min "int policy"
.Ft int
.Fn sched_rr_get_interval "pid_t pid" "struct timespec *interval"
.Sh DESCRIPTION
The
.Fn sched_get_priority_max
and
.Fn sched_get_priority_min
functions return the appropriate maximum or minimum, respectively,
for the scheduling policy specified by
.Fa policy .
The
.Fn sched_rr_get_interval
function updates the
.Fa timespec
structure referenced by the
.Fa interval
argument to contain the current execution time limit (i.e., time
quantum) for the process specified by
.Fa pid .
If
.Fa pid
is zero, the current execution time limit for the calling process is
returned.
.Pp
The value of
.Fa policy
should be one of the scheduling policy values defined in
.Fa <sched.h> :
.Bl -tag -width [SCHED_OTHER]
.It Bq Er SCHED_FIFO
First-in-first-out fixed priority scheduling with no round robin scheduling;
.It Bq Er SCHED_OTHER
The standard time sharing scheduler;
.It Bq Er SCHED_RR
Round-robin scheduling across same priority processes.
.El
.Sh RETURN VALUES
If successful, the
.Fn sched_get_priority_max
and
.Fn sched_get_priority_min
functions shall return the appropriate maximum or minimum values,
respectively.  If unsuccessful, they shall return a value of -1 and set
.Fa errno
to indicate the error.
.Pp
.Rv -std sched_rr_get_interval
.Sh ERRORS
On failure
.Va errno
will be set to the corresponding value:
.Bl -tag -width Er
.It Bq Er EINVAL
The value of the
.Fa policy
parameter does not represent a defined scheduling policy.
.It Bq Er ENOSYS
The
.Fn sched_get_priority_max ,
.Fn sched_get_priority_min ,
and
.Fn sched_rr_get_interval
functions are not supported by the implementation.
.It Bq Er ESRCH
No process can be found corresponding to that specified by
.Fa pid .
.El
.Sh SEE ALSO
.Xr sched_getparam 2 ,
.Xr sched_getscheduler 2 ,
.Xr sched_setparam 2 ,
.Xr sched_setscheduler 2
.Sh STANDARDS
The
.Fn sched_get_priority_max ,
.Fn sched_get_priority_min ,
and
.Fn sched_rr_get_interval
functions conform to
.St -p1003.1b-93 .