PTHREAD_ATTR_SETAFFINITY_NPLinux Programmer's MaPTHREAD_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 configura-
	      tion option CONFIG_NR_CPUS defines the range  of	the  set  sup-
	      ported 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 4.10 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				  2015-07-23	PTHREAD_ATTR_SETAFFINITY_NP(3)