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¶
The
cpuset_getaffinity
family of system calls
first appeared in
FreeBSD 7.1.
AUTHOR¶
Jeffrey Roberson
⟨jeff@FreeBSD.org⟩