172 lines
5.3 KiB
Groff
172 lines
5.3 KiB
Groff
.\" $FreeBSD$
|
|
.\" 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_SETPARAM 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm sched_setparam ,
|
|
.Nm sched_getparam
|
|
.Nd set/get scheduling parameters
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In sched.h
|
|
.Ft int
|
|
.Fn sched_setparam "pid_t pid" "const struct sched_param *param"
|
|
.Ft int
|
|
.Fn sched_getparam "pid_t pid" "struct sched_param *param"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn sched_setparam
|
|
system call sets the scheduling parameters of the process specified by
|
|
.Fa pid
|
|
to the values specified by the
|
|
.Fa sched_param
|
|
structure pointed to by
|
|
.Fa param .
|
|
The value of the
|
|
.Fa sched_priority
|
|
member in the
|
|
.Fa param
|
|
structure must be any integer within the inclusive priority range for
|
|
the current scheduling policy of the process specified by
|
|
.Fa pid .
|
|
Higher numerical values for the priority represent higher priorities.
|
|
.Pp
|
|
In this implementation, if the value of
|
|
.Fa pid
|
|
is negative the system call will fail.
|
|
.Pp
|
|
If a process specified by
|
|
.Fa pid
|
|
exists and if the calling process has permission, the scheduling
|
|
parameters are set for the process whose process ID is equal to
|
|
.Fa pid .
|
|
.Pp
|
|
If
|
|
.Fa pid
|
|
is zero, the 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
|
|
.St -p1003.1b-93
|
|
as a write-style operation.
|
|
.Pp
|
|
The target process, whether it is running or not running, will resume
|
|
execution after all other runnable processes of equal or greater
|
|
priority have been scheduled to run.
|
|
.Pp
|
|
If the priority of the process specified by the
|
|
.Fa pid
|
|
argument is set higher than that of the lowest priority running process
|
|
and if the specified process is ready to run, the process specified by
|
|
the
|
|
.Fa pid
|
|
argument will preempt a lowest priority running process. Similarly, if
|
|
the process calling
|
|
.Fn sched_setparam
|
|
sets its own priority lower than that of one or more other nonempty
|
|
process lists, then the process that is the head of the highest priority
|
|
list will also preempt the calling process. Thus, in either case, the
|
|
originating process might not receive notification of the completion of
|
|
the requested priority change until the higher priority process has
|
|
executed.
|
|
.Pp
|
|
In this implementation, when the current scheduling policy for the
|
|
process specified by
|
|
.Fa pid
|
|
is normal timesharing (SCHED_OTHER, aka SCHED_NORMAL when not POSIX-source)
|
|
or the idle policy (SCHED_IDLE when not POSIX-source) then the behavior
|
|
is as if the process had been running under SCHED_RR with a priority
|
|
lower than any actual realtime priority.
|
|
.Pp
|
|
The
|
|
.Fn sched_getparam
|
|
system call will return the scheduling parameters of a process specified
|
|
by
|
|
.Fa pid
|
|
in the
|
|
.Fa sched_param
|
|
structure pointed to by
|
|
.Fa param .
|
|
.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
|
|
.St -p1003.1b-93
|
|
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_getparam
|
|
system call will fail if
|
|
.Fa pid
|
|
is negative.
|
|
.Sh RETURN VALUES
|
|
.Rv -std
|
|
.Sh ERRORS
|
|
On failure
|
|
.Va errno
|
|
will be set to the corresponding value:
|
|
.Bl -tag -width Er
|
|
.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
|
|
.St -p1003.1b-93 .
|
|
.It Bq Er ESRCH
|
|
No process can be found corresponding to that specified by
|
|
.Fa pid .
|
|
.It Bq Er EINVAL
|
|
For
|
|
.Fn sched_setparam :
|
|
one or more of the requested scheduling parameters
|
|
is outside the range defined for the scheduling policy of the specified
|
|
.Fa pid .
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr sched_getscheduler 2 ,
|
|
.Xr sched_get_priority_max 2 ,
|
|
.Xr sched_get_priority_min 2 ,
|
|
.Xr sched_rr_get_interval 2 ,
|
|
.Xr sched_setscheduler 2 ,
|
|
.Xr sched_yield 2
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn sched_setparam
|
|
and
|
|
.Fn sched_getparam
|
|
system calls conform to
|
|
.St -p1003.1b-93 .
|