2008-11-12 18:31:28 +00:00
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.\" Copyright (C) 2006 Michael Kerrisk
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.\" and Copyright (C) 2008 Linux Foundation, written by Michael Kerrisk
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.\" <mtk.manpages@gmail.com>
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.TH CPU_SET 2 2008-11-12 "Linux" "Linux Programmer's Manual"
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.SH NAME
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CPU_CLR, CPU_ISSET, CPU_SET, CPU_ZERO \-
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macros for manipulating CPU sets
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.SH SYNOPSIS
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.nf
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.B #define _GNU_SOURCE
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.B #include <sched.h>
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.sp
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.BI "void CPU_CLR(int " cpu ", cpu_set_t *" set );
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.br
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.BI "int CPU_ISSET(int " cpu ", cpu_set_t *" set );
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.br
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.BI "void CPU_SET(int " cpu ", cpu_set_t *" set );
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.br
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.BI "void CPU_ZERO(cpu_set_t *" set );
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.fi
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.SH DESCRIPTION
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The
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.I cpu_set_t
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data structure represents a set of CPUs.
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CPU sets are used by
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.BR sched_setaffinity (2)
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and similar interfaces.
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The following macros are provided to operate on the CPU set
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.IR set :
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.TP 16
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.BR CPU_ZERO ()
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clears
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.I set
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so that it contains no CPUs.
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.TP
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.BR CPU_SET ()
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adds CPU
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.I cpu
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to
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.IR set .
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.TP
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.BR CPU_CLR ()
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removes CPU
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.I cpu
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from
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.IR set .
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.TP
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.BR CPU_ISSET ()
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tests to see if CPU
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.I cpu
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is a member of
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.IR set .
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.PP
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Where a
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.I cpu
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argument is specified, it should not produce side effects,
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since the above macros may evaluate the argument more than once.
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.PP
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The first available CPU on the system corresponds to a
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.I cpu
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value of 0, the next CPU corresponds to a
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.I cpu
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value of 1, and so on.
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The constant
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.B CPU_SETSIZE
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(1024) specifies a value one greater than the maximum CPU
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number that can be stored in a CPU set.
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.SH "RETURN VALUE"
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.BR CPU_ISSET ()
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returns non-zero if
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.I cpu
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is in
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.IR set ;
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otherwise, it returns 0.
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The other functions do not return a value.
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.\" .SH ERRORS
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.\" AFAICT, no E* errors are occur.
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.SH VERSIONS
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The
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.BR CPU_ZERO (),
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.BR CPU_CLR (),
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.BR CPU_SET (),
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and
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.BR CPU_ISSET ()
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macros were added in glibc 2.3.3.
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.SH "CONFORMING TO"
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These interfaces are Linux-specific.
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.SH "SEE ALSO"
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.BR sched_setaffinity (2),
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.BR CPU_SET (3),
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.BR pthread_attr_setaffinity_np (3),
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.BR pthread_setaffinity_np (3),
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.BR cpuset (7)
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