v7 man page for pthread_attr_getaffinity_np

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)