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
<davidxu@FreeBSD.org>,
and this manpage was written by Xin LI
<delphij@FreeBSD.org>.