277 lines
7.2 KiB
Groff
277 lines
7.2 KiB
Groff
.\" $NetBSD: sched.3,v 1.11 2011/12/04 21:08:44 jym Exp $
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.\"
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.\" Copyright (c) 2008 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Mindaugas Rasiukevicius <rmind at NetBSD org>.
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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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd December 4, 2011
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.Dt SCHED 3
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.Os
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.Sh NAME
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.Nm sched_setparam ,
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.Nm sched_getparam ,
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.Nm sched_setscheduler ,
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.Nm sched_getscheduler ,
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.Nm sched_get_priority_max ,
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.Nm sched_get_priority_min ,
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.Nm sched_rr_get_interval ,
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.Nm sched_yield
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.Nd process scheduling
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.Sh LIBRARY
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.Lb librt
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.Sh SYNOPSIS
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.In sched.h
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.Ft int
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.Fn sched_setparam "pid_t pid" "const struct sched_param *param"
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.Ft int
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.Fn sched_getparam "pid_t pid" "struct sched_param *param"
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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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.Ft int
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.Fn sched_get_priority_max "int policy"
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.Ft int
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.Fn sched_get_priority_min "int policy"
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.Ft int
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.Fn sched_rr_get_interval "pid_t pid" "struct timespec *interval"
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.Ft int
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.Fn sched_yield "void"
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.Sh DESCRIPTION
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This section describes the functions used to get scheduling information
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about processes, and control the scheduling of processes.
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.Pp
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Available scheduling policies (classes) are:
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.Bl -tag -width SCHED_OTHER
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.It Dv SCHED_OTHER
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Time-sharing (TS) scheduling policy.
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The default policy in
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.Nx .
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.It Dv SCHED_FIFO
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First in, first out (FIFO) scheduling policy.
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.It Dv SCHED_RR
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Round robin scheduling policy.
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.El
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.Pp
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The
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.Fa struct sched_param
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contains at least one member:
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.Bl -tag -width flags
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.It Fa sched_priority
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Specifies the priority of the process.
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.El
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.Sh FUNCTIONS
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.Bl -tag -width compact
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.It Fn sched_setparam pid param
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Sets the scheduling parameters for the process specified by
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.Fa pid
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to
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.Fa param .
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If the value of
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.Fa pid
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is equal to zero, then the calling process is used.
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.It Fn sched_getparam pid param
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Gets the scheduling parameters of the process specified by
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.Fa pid
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into the structure
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.Fa param .
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If the value of
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.Fa pid
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is equal to zero, then the calling process is used.
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.It Fn sched_setscheduler pid policy param
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Set the scheduling policy and parameters for the process specified by
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.Fa pid .
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If the value of
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.Fa pid
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is equal to zero, then the calling process is used.
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.It Fn sched_getscheduler pid
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Returns the scheduling policy of the process specified by
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.Fa pid .
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If the value of
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.Fa pid
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is equal to zero, then the calling process is used.
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.It Fn sched_get_priority_max policy
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Returns the maximal priority which may be used for the scheduling policy
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specified by
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.Fa policy .
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.It Fn sched_get_priority_min policy
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Returns the minimal priority which may be used for the scheduling policy
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specified by
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.Fa policy .
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.It Fn sched_rr_get_interval pid interval
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Returns the time quantum into the structure
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.Fa interval
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of the process specified by
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.Fa pid .
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If the value of
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.Fa pid
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is equal to zero, then the calling process is used.
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The process must be running at
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.Fa SCHED_RR
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scheduling policy.
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.It Fn sched_yield
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Yields a processor voluntarily and gives other threads a chance to run
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without waiting for an involuntary preemptive switch.
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.It Fn sched_setaffinity_np pid size cpuset
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Set the affinity mask specified by
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.Fa cpuset
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for the process specified by
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.Fa pid .
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At least one valid CPU must be set in the mask.
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.It Fn sched_getaffinity_np pid size cpuset
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Get the affinity mask of the process specified by
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.Fa pid
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into the
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.Fa cpuset .
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.El
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.Sh IMPLEMENTATION NOTES
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Setting CPU
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.Xr affinity 3
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requires super-user privileges.
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Ordinary users can be allowed to control CPU affinity
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of their threads via the
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.Pa security.models.extensions.user_set_cpu_affinity
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.Xr sysctl 7 .
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See
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.Xr secmodel_extensions 9 .
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.Pp
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Portable applications should not use the
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.Fn sched_setaffinity_np
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and
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.Fn sched_getaffinity_np
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functions.
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.Sh RETURN VALUES
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.Fn sched_setparam ,
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.Fn sched_getparam ,
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.Fn sched_rr_get_interval ,
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and
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.Fn sched_yield
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return 0 on success.
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Otherwise, \-1 is returned and
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.Va errno
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is set to indicate the error.
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.Pp
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.Fn sched_setscheduler
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returns the previously used scheduling policy on success.
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Otherwise, \-1 is returned and
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.Va errno
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is set to indicate the error.
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.Pp
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.Fn sched_getscheduler
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returns the scheduling policy on success.
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Otherwise, \-1 is returned and
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.Va errno
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is set to indicate the error.
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.Pp
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.Fn sched_get_priority_max
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and
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.Fn sched_get_priority_min
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return the maximal/minimal priority value on success.
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Otherwise, \-1 is returned and
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.Va errno
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is set to indicate the error.
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.Pp
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.Fn sched_setaffinity_np
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and
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.Fn sched_getaffinity_np
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return 0 on success.
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Otherwise, \-1 is returned and
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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The
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.Fn sched_setparam
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and
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.Fn sched_setscheduler
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functions fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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At least one of the specified scheduling parameters was invalid.
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.It Bq Er EPERM
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The calling process has no appropriate privileges to perform the operation.
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.It Bq Er ESRCH
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No process can be found corresponding to the PID specified by
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.Fa pid ,
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and the value of
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.Fa pid
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is not zero.
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.El
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.Pp
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The
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.Fn sched_getparam
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and
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.Fn sched_getscheduler
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functions fail if:
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.Bl -tag -width Er
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.It Bq Er EPERM
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The calling process is not a super-user and its effective user id does not
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match the effective user-id of the specified process.
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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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and the value of
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.Fa pid
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is not zero.
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.El
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.Pp
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The
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.Fn sched_get_priority_max
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and
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.Fn sched_get_priority_min
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functions fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The specified scheduling policy is invalid.
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.El
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.Pp
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The
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.Fn sched_rr_get_interval
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function fails if:
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.Bl -tag -width Er
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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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and the value of
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.Fa pid
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is not zero.
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.El
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.Sh SEE ALSO
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.Xr affinity 3 ,
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.Xr cpuset 3 ,
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.Xr pset 3 ,
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.Xr schedctl 8
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.Sh STANDARDS
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These functions, except
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.Fn sched_setaffinity_np
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and
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.Fn sched_getaffinity_np ,
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are expected to conform the
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.St -p1003.1-2001
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standard.
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.Sh HISTORY
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The scheduling functions appeared in
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.Nx 5.0 .
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