pthread_attr_setaffinity_np(3) — Linux manual pages

Linux manual pages	Section 3: Subroutines

Name

pthread_attr_setaffinity_np, pthread_attr_getaffinity_np — set/get CPU affinity attribute in thread attributes object

Synopsis

#define _GNU_SOURCE              /* See feature_test_macros(7) */
#include <pthread.h>

`int pthread_attr_setaffinity_np(`	pthread_attr_t *`attr`,
	size_t `cpusetsize`,
	const cpu_set_t *`cpuset)`;

`int pthread_attr_getaffinity_np(`	pthread_attr_t *`attr`,
	size_t `cpusetsize`,
	cpu_set_t *`cpuset)`;

	Note
	Compile and link with `−pthread`.

DESCRIPTION

The pthread_attr_setaffinity_np() function sets the CPU affinity mask attribute of the thread attributes object referred to by attr to the value specified in cpuset. This attribute determines the CPU affinity mask of a thread created using the thread attributes object attr.

The pthread_attr_getaffinity_np() function returns the CPU affinity mask attribute of the thread attributes object referred to by attr in the buffer pointed to by cpuset.

The argument cpusetsize is the length (in bytes) of the buffer pointed to by cpuset. Typically, this argument would be specified as sizeof(cpu_set_t).

For more details on CPU affinity masks, see sched_setaffinity(2). For a description of a set of macros that can be used to manipulate and inspect CPU sets, see CPU_SET(3).

RETURN VALUE

On success, these functions return 0; on error, they return a nonzero error number.

ERRORS

EINVAL: (pthread_attr_setaffinity_np()) cpuset specified a CPU that was outside the set supported by the kernel. (The kernel configuration option CONFIG_NR_CPUS defines the range of the set supported by the kernel data type used to represent CPU sets.)
EINVAL: (pthread_attr_getaffinity_np()) A CPU in the affinity mask of the thread attributes object referred to by attr lies outside the range specified by cpusetsize (i.e., cpuset/cpusetsize is too small).
ENOMEM: (pthread_attr_setaffinity_np()) Could not allocate memory.

VERSIONS

These functions are provided by glibc since version 2.3.4.

CONFORMING TO

These functions are nonstandard GNU extensions; hence the suffix "_np" (nonportable) in the names.

NOTES

In glibc 2.3.3 only, versions of these functions were provided that did not have a cpusetsize argument. Instead the CPU set size given to the underlying system calls was always sizeof(cpu_set_t).

COLOPHON

This page is part of release 3.52 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man−pages/.

  Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
    <mtk.manpagesgmail.com>

%%%LICENSE_START(VERBATIM)
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.
%%%LICENSE_END