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
       #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);

       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).

SEE ALSO
       sched_setaffinity(2), pthread_attr_init(3), pthread_setaffinity_np(3), cpuset(7), pthreads(7)

COLOPHON
       This page is part of release 3.25 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/.



Linux                                                      2009-02-01                             PTHREAD_ATTR_SETAFFINITY_NP(3)