freebsd-dev/lib/libc/sys/sched_setscheduler.2
Peter Dufault 8a6472b723 Finish _POSIX_PRIORITY_SCHEDULING. Needs P1003_1B and
_KPOSIX_PRIORITY_SCHEDULING options to work.  Changes:

Change all "posix4" to "p1003_1b".  Misnamed files are left
as "posix4" until I'm told if I can simply delete them and add
new ones;

Add _POSIX_PRIORITY_SCHEDULING system calls for FreeBSD and Linux;

Add man pages for _POSIX_PRIORITY_SCHEDULING system calls;

Add options to LINT;

Minor fixes to P1003_1B code during testing.
1998-03-28 11:51:01 +00:00

168 lines
4.7 KiB
Groff

.\" $Id:$
.\" 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 Mar 12, 1998
.Dt SCHED_SETSCHEDULER 2
.Os BSD 4
.Sh NAME
.Nm sched_setscheduler ,
.Nm sched_getscheduler
.Nd set/get scheduling policy and scheduler parameters
.Sh SYNOPSIS
.Fd #include <sched.h>
.Ft int
.Fn sched_setscheduler "pid_t pid" "int policy" "const struct sched_param *param"
.Ft int
.Fn sched_getscheduler "pid_t pid"
.Sh DESCRIPTION
The
.Fn sched_setscheduler
function sets the scheduling policy and scheduling parameters
of the process specified by
.Fa pid
to
.Fa policy
and the parameters specified in the
.Fa sched_param
structure pointed to by
.Fa param ,
respectively.
The value of the
.Fa sched_priority
member in the
.Fa param
structure must be any integer within the inclusive priority range for
the scheduling policy specified by
.Fa policy .
.Pp
In this implementation, if the value of
.Fa pid
is negative the function will fail.
.Pp
If a process specified by
.Fa pid
exists and if the calling process has permission, the scheduling
policy and scheduling parameters will be set for the process
whose process ID is equal to
.Fa pid .
.Pp
If
.Fa pid
is zero, the scheduling policy and scheduling
parameters are set for the calling process.
.Pp
In this implementation, the policy of when a process can affect
the scheduling parameters of another process is specified in
.Xr p1003_1b
as a write-style operation.
.Pp
The scheduling policies are 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
.Pp
The
.Fa sched_param
structure is defined in
.Fa <sched.h> :
.Bd -literal -offset indent
struct sched_param {
int sched_priority; /* scheduling priority */
};
.Ed
.Pp
The
.Fn sched_getscheduler
function returns the scheduling policy of the process specified
by
.Fa pid .
.Pp
If a process specified by
.Fa pid
exists and if the calling process has permission,
the scheduling parameters for the process whose process ID is equal to
.Fa pid
are returned.
.Pp
In this implementation, the policy of when a process can obtain the
scheduling parameters of another process are detailed in
.Xr p1003_1b
as a read-style operation.
.Pp
If
.Fa pid
is zero, the scheduling parameters for the calling process will be
returned. In this implementation, the
.Fa sched_getscheduler
function will fail if
.Fa pid
is negative.
.Sh RETURN
The function will return zero if it completes successfully, or it
will return a value of -1 and set
.Va errno
to indicate the error.
.Sh ERRORS
On failure
.Va errno
will be set to the corresponding value:
.Bl -tag -width [EFAULT]
.It Bq Er ENOSYS
The system is not configured to support this functionality.
.It Bq Er EPERM
The requesting process doesn not have permission as detailed in
.Xr p1003_1b .
.It Bq Er ESRCH
No process can be found corresponding to that specified by
.Fa pid .
.It Bq Er EINVAL
The value of the
.Fa policy
parameter is invalid, or one or more of the parameters contained in
.Fa param
is outside the valid range for the specified scheduling policy.
.El
.Sh SEE ALSO
.Xr sched_getparam 2 ,
.Xr sched_setparam 2 ,
.Xr sched_get_priority_max 2 ,
.Xr sched_get_priority_min 2 ,
.Xr sched_rr_get_interval 2 ,
.Xr sched_yield 2
.Sh STANDARDS
The
.Fn sched_setscheduler
and
.Fn sched_getscheduler
functions conform to
.St -p1003.1b-93 .