pthread_attr_setaffinity_np(3) — Linux manual page

pthread_...finity_np(3) Library Functions Manual pthread_...finity_np(3)

NAME

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

LIBRARY

       POSIX threads library (libpthread, -lpthread)

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);

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.

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()       │               │         │
       └─────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       GNU; hence the suffix "_np" (nonportable) in the names.

HISTORY

       glibc 2.3.4.

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

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Linux man-pages 6.9.1          2024-05-02        pthread_...finity_np(3)

Pages that refer to this page: CPU_SET(3), pthread_attr_init(3), pthread_attr_setscope(3), pthread_getattr_default_np(3), pthread_getattr_np(3), pthread_setaffinity_np(3)

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