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Man Pages


Manual Reference Pages  -  PTHREAD_ATTR_GETAFFINITY_NP (3)

NAME

pthread_attr_getaffinity_np, pthread_attr_setaffinity_np - manage CPU affinity in thread attribute objects

CONTENTS

Library
Synopsis
Description
Return Values
Errors
See Also
Standards
History
Authors

LIBRARY


.Lb libpthread

SYNOPSIS


.In pthread_np.h int pthread_attr_getaffinity_np const pthread_attr_t *pattr size_t cpusetsize cpuset_t *cpusetp int pthread_attr_setaffinity_np pthread_attr_t *pattr size_t cpusetsize const cpuset_t *cpusetp

DESCRIPTION

The pthread_attr_getaffinity_np and pthread_attr_setaffinity_np functions allow the manipulation of sets of CPUs available to the specified thread attribute object.

Masks of type cpuset_t are composed using the CPU_SET macros. The kernel tolerates large sets as long as all CPUs specified in the set exist. Sets smaller than the kernel uses generate an error on calls to pthread_attr_getaffinity_np even if the result set would fit within the user supplied set. Calls to pthread_attr_setaffinity_np tolerate small sets with no restrictions.

The supplied mask should have a size of cpusetsize bytes. This size is usually provided by calling sizeof(cpuset_t) which is ultimately determined by the value of CPU_SETSIZE as defined in
.In sys/cpuset.h .

pthread_attr_getaffinity_np retrieves the mask from the thread attribute object specified by pattr, and stores it in the space provided by cpusetp.

pthread_attr_setaffinity_np sets the mask for the thread attribute object specified by pattr to the value in cpusetp.

RETURN VALUES

If successful, the pthread_attr_getaffinity_np and pthread_attr_setaffinity_np functions will return zero. Otherwise an error number will be returned to indicate the error.

ERRORS

The pthread_attr_getaffinity_np functions will fail if:
[EINVAL]
  The pattr or the attribute specified by it is NULL.
[ERANGE]
  The cpusetsize is too small.

The pthread_attr_setaffinity_np function will fail if:
[EINVAL]
  The pattr or the attribute specified by it is NULL.
[EINVAL]
  The cpusetp specified a CPU that was outside the set supported by the kernel.
[ERANGE]
  The cpusetsize is too small.
[ENOMEM]
  Insufficient memory exists to store the cpuset mask.

SEE ALSO

cpuset(1), cpuset(2), cpuset_getid(2), cpuset_setid(2), pthread_get_affinity_np(3), pthread_set_affinity_np(3)

STANDARDS

The pthread_attr_getaffinity_np and pthread_attr_setaffinity_np functions are non-standard
.Fx extensions and may be not available on other operating systems.

HISTORY

The pthread_attr_getaffinity_np and pthread_attr_setaffinity_np functions first appeared in
.Fx 7.2 .

AUTHORS


.An -nosplit The pthread_attr_getaffinity_np and pthread_attr_setaffinity_np functions were written by
.An David Xu Aq davidxu@FreeBSD.org , and this manpage was written by
.An Xin LI Aq delphij@FreeBSD.org .
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