pthread_attr_setaffinity_np(3) — Linux manual page



NAME         top

       pthread_attr_setaffinity_np,  pthread_attr_getaffinity_np  -  set/get
       CPU affinity attribute in thread attributes object

SYNOPSIS         top

       #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         top

       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

       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

       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         top

       On success, these functions return 0; on error, they return a nonzero
       error number.

ERRORS         top

       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

       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         top

       These functions are provided by glibc since version 2.3.4.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface                      Attribute     Value   │
       │pthread_attr_setaffinity_np(), │ Thread safety │ MT-Safe │
       │pthread_attr_getaffinity_np()  │               │         │

CONFORMING TO         top

       These functions are nonstandard GNU extensions; hence the suffix
       "_np" (nonportable) in the names.

NOTES         top

       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         top

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

COLOPHON         top

       This page is part of release 5.08 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

Linux                            2017-09-15   PTHREAD_ATTR_SETAFFINITY_NP(3)

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