PTHREAD_ATTR_AFFINITY_NP(3) FreeBSD Library Functions Manual
NAME
pthread_attr_getaffinity_np, pthread_attr_setaffinity_np - manage CPU
affinity in thread attribute objects
LIBRARY
POSIX Threads Library (libpthread, -lpthread)
SYNOPSIS
#include <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. If the
user-supplied mask is not large enough to fit all of the matching CPUs,
pthread_attr_getaffinity_np() fails with ERANGE. Calls to
pthread_attr_setaffinity_np() tolerate masks of any size with no
restrictions. pthread_attr_setaffinity_np() uses the meaningful part of
the mask, where the upper bound is the maximum CPU id present in the
system. If bits for non-existing CPUs are set, calls to
pthread_attr_setaffinity_np() fail with EINVAL.
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_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.
[ENOMEM] Insufficient memory exists to store the cpuset mask.
SEE ALSO
cpuset(1), cpuset(2), cpuset_getid(2), cpuset_setid(2),
pthread_getaffinity_np(3), pthread_np(3), pthread_setaffinity_np(3)
STANDARDS
The pthread_attr_getaffinity_np and pthread_attr_setaffinity_np functions
are non-standard FreeBSD 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 FreeBSD 7.2.
AUTHORS
The pthread_attr_getaffinity_np and pthread_attr_setaffinity_np functions
were written by David Xu <
[email protected]>, and this manpage was
written by Xin LI <
[email protected]>.
FreeBSD 14.1-RELEASE-p8 January 29, 2023 FreeBSD 14.1-RELEASE-p8