170 lines
4.7 KiB
Groff
170 lines
4.7 KiB
Groff
.\" $FreeBSD$
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.\" Copyright (c) 1998 HD Associates, Inc.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd Mar 12, 1998
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.Dt SCHED_SETSCHEDULER 2
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.Os BSD 4
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.Sh NAME
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.Nm sched_setscheduler ,
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.Nm sched_getscheduler
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.Nd set/get scheduling policy and scheduler parameters
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.Fd #include <sched.h>
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.Ft int
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.Fn sched_setscheduler "pid_t pid" "int policy" "const struct sched_param *param"
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.Ft int
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.Fn sched_getscheduler "pid_t pid"
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.Sh DESCRIPTION
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The
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.Fn sched_setscheduler
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function sets the scheduling policy and scheduling parameters
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of the process specified by
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.Fa pid
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to
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.Fa policy
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and the parameters specified in the
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.Fa sched_param
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structure pointed to by
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.Fa param ,
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respectively.
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The value of the
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.Fa sched_priority
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member in the
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.Fa param
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structure must be any integer within the inclusive priority range for
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the scheduling policy specified by
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.Fa policy .
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.Pp
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In this implementation, if the value of
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.Fa pid
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is negative the function will fail.
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.Pp
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If a process specified by
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.Fa pid
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exists and if the calling process has permission, the scheduling
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policy and scheduling parameters will be set for the process
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whose process ID is equal to
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.Fa pid .
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.Pp
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If
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.Fa pid
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is zero, the scheduling policy and scheduling
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parameters are set for the calling process.
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.Pp
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In this implementation, the policy of when a process can affect
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the scheduling parameters of another process is specified in
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.Xr p1003_1b
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as a write-style operation.
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.Pp
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The scheduling policies are in
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.Fa <sched.h> :
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.Bl -tag -width [SCHED_OTHER]
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.It Bq Er SCHED_FIFO
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First-in-first-out fixed priority scheduling with no round robin scheduling;
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.It Bq Er SCHED_OTHER
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The standard time sharing scheduler;
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.It Bq Er SCHED_RR
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Round-robin scheduling across same priority processes.
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.El
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.Pp
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The
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.Fa sched_param
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structure is defined in
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.Fa <sched.h> :
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.Bd -literal -offset indent
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struct sched_param {
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int sched_priority; /* scheduling priority */
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};
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.Ed
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.Pp
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The
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.Fn sched_getscheduler
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function returns the scheduling policy of the process specified
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by
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.Fa pid .
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.Pp
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If a process specified by
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.Fa pid
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exists and if the calling process has permission,
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the scheduling parameters for the process whose process ID is equal to
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.Fa pid
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are returned.
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.Pp
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In this implementation, the policy of when a process can obtain the
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scheduling parameters of another process are detailed in
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.Xr p1003_1b
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as a read-style operation.
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.Pp
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If
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.Fa pid
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is zero, the scheduling parameters for the calling process will be
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returned. In this implementation, the
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.Fa sched_getscheduler
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function will fail if
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.Fa pid
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is negative.
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.Sh RETURN
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The function will return zero if it completes successfully, or it
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will return a value of -1 and set
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.Va errno
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to indicate the error.
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.Sh ERRORS
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On failure
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.Va errno
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will be set to the corresponding value:
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.Bl -tag -width Er
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.It Bq Er ENOSYS
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The system is not configured to support this functionality.
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.It Bq Er EPERM
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The requesting process doesn not have permission as detailed in
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.Xr p1003_1b .
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.It Bq Er ESRCH
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No process can be found corresponding to that specified by
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.Fa pid .
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.It Bq Er EINVAL
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The value of the
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.Fa policy
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parameter is invalid, or one or more of the parameters contained in
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.Fa param
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is outside the valid range for the specified scheduling policy.
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.El
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.Sh SEE ALSO
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.Xr sched_get_priority_max 2 ,
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.Xr sched_get_priority_min 2 ,
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.Xr sched_getparam 2 ,
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.Xr sched_rr_get_interval 2 ,
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.Xr sched_setparam 2 ,
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.Xr sched_yield 2
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.Sh STANDARDS
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The
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.Fn sched_setscheduler
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and
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.Fn sched_getscheduler
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functions conform to
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.St -p1003.1b-93 .
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