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CPU_SET.3: New page documenting CPU_* macros 

This page contains material moved out of sched_setscheduler(2).
It overwrites a previously existing link file with the same name.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
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Michael Kerrisk 2008-11-12 13:31:28 -05:00
parent ad3f4748db
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.so man2/sched_setaffinity.2
.\" Copyright (C) 2006 Michael Kerrisk
.\" and Copyright (C) 2008 Linux Foundation, written by Michael Kerrisk
.\" <mtk.manpages@gmail.com>
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.TH CPU_SET 2 2008-11-12 "Linux" "Linux Programmer's Manual"
.SH NAME
CPU_CLR, CPU_ISSET, CPU_SET, CPU_ZERO \-
macros for manipulating CPU sets
.SH SYNOPSIS
.nf
.B #define _GNU_SOURCE
.B #include <sched.h>
.sp
.BI "void CPU_CLR(int " cpu ", cpu_set_t *" set );
.br
.BI "int CPU_ISSET(int " cpu ", cpu_set_t *" set );
.br
.BI "void CPU_SET(int " cpu ", cpu_set_t *" set );
.br
.BI "void CPU_ZERO(cpu_set_t *" set );
.fi
.SH DESCRIPTION
The
.I cpu_set_t
data structure represents a set of CPUs.
CPU sets are used by
.BR sched_setaffinity (2)
and similar interfaces.
The following macros are provided to operate on the CPU set
.IR set :
.TP 16
.BR CPU_ZERO ()
clears
.I set
so that it contains no CPUs.
.TP
.BR CPU_SET ()
adds CPU
.I cpu
to
.IR set .
.TP
.BR CPU_CLR ()
removes CPU
.I cpu
from
.IR set .
.TP
.BR CPU_ISSET ()
tests to see if CPU
.I cpu
is a member of
.IR set .
.PP
Where a
.I cpu
argument is specified, it should not produce side effects,
since the above macros may evaluate the argument more than once.
.PP
The first available CPU on the system corresponds to a
.I cpu
value of 0, the next CPU corresponds to a
.I cpu
value of 1, and so on.
The constant
.B CPU_SETSIZE
(1024) specifies a value one greater than the maximum CPU
number that can be stored in a CPU set.
.SH "RETURN VALUE"
.BR CPU_ISSET ()
returns non-zero if
.I cpu
is in
.IR set ;
otherwise, it returns 0.
The other functions do not return a value.
.\" .SH ERRORS
.\" AFAICT, no E* errors are occur.
.SH VERSIONS
The
.BR CPU_ZERO (),
.BR CPU_CLR (),
.BR CPU_SET (),
and
.BR CPU_ISSET ()
macros were added in glibc 2.3.3.
.SH "CONFORMING TO"
These interfaces are Linux-specific.
.SH "SEE ALSO"
.BR sched_setaffinity (2),
.BR CPU_SET (3),
.BR pthread_attr_setaffinity_np (3),
.BR pthread_setaffinity_np (3),
.BR cpuset (7)