table of contents
CPUSET_GETAFFINITY(2) | System Calls Manual | CPUSET_GETAFFINITY(2) |
NAME¶
cpuset_getaffinity
,
cpuset_setaffinity
—
manage CPU affinity
LIBRARY¶
Standard C Library (libc, -lc)SYNOPSIS¶
#include
<sys/param.h>
#include
<sys/cpuset.h>
int
cpuset_getaffinity
(cpulevel_t
level,
cpuwhich_t
which, id_t
id, size_t
setsize,
cpuset_t *mask);
int
cpuset_setaffinity
(cpulevel_t
level,
cpuwhich_t
which, id_t
id, size_t
setsize, const
cpuset_t *mask);
DESCRIPTION¶
cpuset_getaffinity
() and
cpuset_setaffinity
() allow the manipulation
of sets of CPUs available to processes, threads, interrupts, jails and other
resources. These functions may manipulate sets of CPUs that contain many
processes or per-object anonymous masks that effect only a single object.
The valid values for the level and
which arguments are documented in
cpuset(2). These arguments specify which object
and which set of the object we are referring to. Not all possible combinations
are valid. For example, only processes may belong to a numbered set accessed
by a level argument of
CPU_LEVEL_CPUSET
. All resources, however,
have a mask which may be manipulated with
CPU_LEVEL_WHICH
.
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
cpuset_getaffinity
() even if the result set
would fit within the user supplied set. Calls to
cpuset_setaffinity
() tolerate small sets
with no restrictions.
The supplied mask should have a size of setsize
bytes. This size is usually provided by calling
sizeof(mask)
which is ultimately determined by the
value of CPU_SETSIZE
as defined in
<sys/cpuset.h>
.
cpuset_getaffinity
() retrieves the mask from
the object specified by level,
which and id
and stores it in the space provided by mask.
cpuset_setaffinity
() attempts to set the mask
for the object specified by level,
which and id
to the value in mask.
RETURN VALUES¶
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.ERRORS¶
The following error codes may be set in errno:- [
EINVAL
] - The level or which argument was not a valid value.
- [
EINVAL
] - The mask argument specified when calling
cpuset_setaffinity
() was not a valid value. - [
EDEADLK
] - The
cpuset_setaffinity
() 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 mask pointer passed was invalid.
- [
ESRCH
] - The object specified by the id and which arguments could not be found.
- [
ERANGE
] - The cpusetsize was either preposterously large or smaller than the kernel set size.
- [
EPERM
] - The calling process did not have the credentials required to complete the operation.
SEE ALSO¶
cpuset(1), cpuset(2), cpuset_getid(2), cpuset_setid(2), pthread_affinity_np(3), pthread_attr_affinity_np(3)HISTORY¶
Thecpuset_getaffinity
family of system calls
first appeared in FreeBSD 7.1.
AUTHOR¶
Jeffrey Roberson ⟨jeff@FreeBSD.org⟩
September 10, 2010 | Debian |