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.  Typ‐
       ically, 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 cpuset‐
       size 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 3.74 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 http://www.kernel.org/doc/man-pages/.



Linux                                       2014-05-28             PTHREAD_ATTR_SETAFFINITY_NP(3)