100 lines
3.3 KiB
Groff
100 lines
3.3 KiB
Groff
.\" $NetBSD: pthread_attr_getscope.3,v 1.2 2010/07/07 10:22:33 njoly Exp $
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.\"
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.\" Copyright (c) 2010 Jukka Ruohonen <jruohonen@iki.fi>
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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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.\"
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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 July 7, 2010
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.Dt PTHREAD_ATTR_GETSCOPE 3
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.Os
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.Sh NAME
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.Nm pthread_attr_getscope
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.Nd get and set the contention scope attribute
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.Sh LIBRARY
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.Lb libpthread
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.Sh SYNOPSIS
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.In pthread.h
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.Ft int
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.Fn pthread_attr_getscope \
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"const pthread_attr_t * restrict attr" "int * restrict contentionscope"
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.Ft int
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.Fn pthread_attr_setscope "pthread_attr_t *attr" "int contentionscope"
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.Sh DESCRIPTION
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The
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.Fn pthread_attr_getscope
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and
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.Fn pthread_attr_setscope
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functions get and set, respectively, the contention scope attribute in the
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.Fa attr
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object.
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.Pp
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The
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.Fa contentionscope
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parameter specifies the scheduling contention scope of a thread.
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It is only possible to set the scope of a thread before the thread is created.
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There are two possible contention scopes:
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.Bl -tag -width PTHREAD_SCOPE_PROCESS -offset 2n
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.It Dv PTHREAD_SCOPE_SYSTEM
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The thread will contend for
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.Tn CPU
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resources with all other processes and threads in the system.
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Generally this means that the user thread is bound directly to the
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kernel scheduling for its entire lifetime.
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.It Dv PTHREAD_SCOPE_PROCESS
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The thread will contend with other threads with the same scope attribute.
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In general, this means that all
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.Dv PTHREAD_SCOPE_PROCESS
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threads are grouped together and this group of threads contends for
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.Tn CPU
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resources.
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This is commonly seen to require a hybrid
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.Pq Dq M:N
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threading model in order to multiplex the user and kernel space scheduling.
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.El
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.Pp
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Only
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.Dv PTHREAD_SCOPE_SYSTEM
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is supported in
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.Nx .
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.Sh RETURN VALUES
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Upon successful completion, both functions return 0.
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Otherwise an error number is returned to indicate the error.
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.Sh ERRORS
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No errors are defined for
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.Fn pthread_attr_getscope .
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.Pp
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The
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.Fn pthread_attr_setscope
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function shall fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Invalid parameter.
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.El
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.Sh SEE ALSO
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.Xr pthread_attr 3 ,
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.Xr csf 9
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.Sh STANDARDS
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Both functions conform to
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.St -p1003.1-96 .
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