PTHREAD_ATTR_SETAFFINITY_NP(3) Linux Programmer's Manual PTHREAD_ATTR_SETAFFINITY_NP(3)
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(const pthread_attr_t *attr,
size_t cpusetsize, cpu_set_t *cpuset);
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.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
+-------------------------------+---------------+---------+
|Interface | Attribute | Value |
+-------------------------------+---------------+---------+
|pthread_attr_setaffinity_np(), | Thread safety | MT-Safe |
|pthread_attr_getaffinity_np() | | |
+-------------------------------+---------------+---------+
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).
SEE ALSO
sched_setaffinity(2), pthread_attr_init(3), pthread_setaffinity_np(3), cpuset(7), pthreads(7)
COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the
latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
Linux 2017-09-15 PTHREAD_ATTR_SETAFFINITY_NP(3)