PTHREAD_AFFINITY_NP(3)					   BSD Library Functions Manual 				    PTHREAD_AFFINITY_NP(3)

NAME

     pthread_getaffinity_np, pthread_setaffinity_np -- manage CPU affinity

LIBRARY

     POSIX Threads Library (libpthread, -lpthread)

SYNOPSIS

     #include <pthread_np.h>

     int
     pthread_getaffinity_np(pthread_t td, size_t cpusetsize, cpuset_t *cpusetp);

     int
     pthread_setaffinity_np(pthread_t td, size_t cpusetsize, const cpuset_t *cpusetp);

DESCRIPTION

     pthread_getaffinity_np() and pthread_setaffinity_np() allow the manipulation of sets of CPUs available to the specified thread.

     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_getaffinity_np() even if the result set would fit within the
     user supplied set.  Calls to pthread_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 <sys/cpuset.h>.

     pthread_getaffinity_np() retrieves the mask from the thread specified by td, and stores it in the space provided by cpusetp.

     pthread_setaffinity_np() attempts to set the mask for the thread specified by td to the value in cpusetp.

RETURN VALUES

     If successful, the pthread_getaffinity_np() and pthread_setaffinity_np() functions will return zero.  Otherwise an error number will be
     returned to indicate the error.

ERRORS

     The pthread_getaffinity_np() and pthread_setaffinity_np() functions may fail if:

     [EDEADLK]		The pthread_setaffinity_np() call would leave a thread without a valid CPU to run on because the set does not overlap with
			the thread's anonymous mask.

     [EFAULT]		The cpusetp pointer passed was invalid.

     [ESRCH]		The thread specified by the td argument could not be found.

     [ERANGE]		The cpusetsize was either preposterously large or smaller than the kernel set size.

     [EPERM]		The calling thread did not have the credentials required to complete the operation.

SEE ALSO

     cpuset(1), cpuset(2), cpuset_getid(2), cpuset_setid(2), pthread(3), pthread_attr_getaffinity_np(3), pthread_attr_setaffinity_np(3)

STANDARDS

     The pthread_getaffinity_np and pthread_setaffinity_np functions are non-standard FreeBSD extensions and may be not available on other operat-
     ing systems.

HISTORY

     The pthread_getaffinity_np and pthread_setaffinity_np function first appeared in FreeBSD 7.2.

AUTHORS

     The pthread_getaffinity_np and pthread_setaffinity_np functions were written by David Xu <davidxu@FreeBSD.org>, and this manpage was written
     by Xin LI <delphij@FreeBSD.org>.

BSD
								  March 23, 2010							       BSD