2008-11-05 04:39:33 +00:00
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.\" 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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.\" 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.\" manual page may be incorrect or out-of-date.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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.\" professionally.
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.\"
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2008-11-14 16:40:32 +00:00
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.TH PTHREAD_ATTR_SETAFFINITY_NP 3 2008-11-14 "Linux" "Linux Programmer's Manual"
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.SH NAME
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pthread_attr_setaffinity_np, pthread_attr_getaffinity_np \- set/get
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CPU affinity attribute in thread attributes object
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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 <pthread.h>
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.BI "int pthread_attr_setaffinity_np(pthread_attr_t " attr ,
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.BI " size_t " cpusetsize ", const cpu_set_t *" cpuset );
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.BI "int pthread_attr_getaffinity_np(pthread_attr_t " attr ,
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.BI " size_t " cpusetsize ", cpu_set_t *" cpuset );
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.sp
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Compile and link with \fI\-pthread\fP.
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.SH DESCRIPTION
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The
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.BR pthread_attr_setaffinity_np ()
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sets the CPU affinity mask attribute of the
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thread attributes object referred to by
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.I attr
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to the value specified in
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.IR cpuset .
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This attribute determines the CPU affinity mask
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of a thread created using the thread attributes object
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.IR attr .
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The
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.BR pthread_attr_getaffinity_np ()
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returns the CPU affinity mask attribute of the thread attributes object
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referred to by
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.IR attr
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in the buffer pointed to by
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.IR cpuset .
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The argument
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.I cpusetsize
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is the length (in bytes) of the buffer pointed to by
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.IR cpuset .
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Typically, this argument would be specified as
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.IR sizeof(cpu_set_t) .
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2008-11-12 18:47:08 +00:00
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For more details on CPU affinity masks, see
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.BR sched_setaffinity (2).
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For a description of a set of macros
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that can be used to manipulate and inspect CPU sets, see
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.BR CPU_SET (3).
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.SH RETURN VALUE
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On success, these functions return 0;
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on error, they return a non-zero error number.
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.SH ERRORS
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.TP
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.BR EINVAL
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.RB ( pthread_attr_setaffinity_np ())
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.I cpuset
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specified a CPU that was outside the set supported by the kernel.
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(The kernel configuration option
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.BR CONFIG_NR_CPUS
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defines the range of the set supported by the kernel data type
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.\" cpumask_t
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used to represent CPU sets.)
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.\" The raw sched_getaffinity() system call returns the size (in bytes)
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.\" of the cpumask_t type.
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.TP
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.B EINVAL
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.RB ( pthread_attr_getaffinity_np ())
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A CPU in the affinity mask of the thread attributes object referred to by
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.I attr
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lies outside the range specified by
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.IR cpusetsize
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(i.e.,
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.IR cpuset / cpusetsize
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is too small).
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.TP
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.B ENOMEM
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.RB ( pthread_attr_setaffinity_np ())
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Could not allocate memory.
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.SH VERSIONS
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These functions are provided by glibc since version 2.3.4.
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.SH CONFORMING TO
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2008-11-05 13:59:40 +00:00
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These functions are non-standard GNU extensions;
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hence the suffix "_np" (non-portable) in the names.
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.SH NOTES
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In glibc 2.3.3 only,
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versions of these functions were provided that did not have a
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.I cpusetsize
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argument.
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Instead the CPU set size given to the underlying system calls was always
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.IR sizeof(cpu_set_t) .
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.SH SEE ALSO
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.BR sched_setaffinity (2),
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.BR pthread_attr_init (3),
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.BR pthread_setaffinity_np (3),
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.BR cpuset (7),
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.BR pthreads (7)
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