manage memory domain policy
Standard C Library (libc, -lc)
which, id_t id,
which, id_t id,
const domainset_t *mask,
cpuset_setdomain() allow the manipulation of sets of
memory domains and allocation policy available to processes, threads, jails
and other resources. These functions may manipulate sets of memory domains
that contain many processes or per-object anonymous masks that affect only a
The valid values for the level and
which arguments are documented in
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
Masks of type domainset_t are composed using
DOMAINSET macros. The kernel tolerates large
sets as long as all domains specified in the set exist. Sets smaller than
the kernel uses generate an error on calls to
cpuset_getdomain() even if the result set would fit
within the user supplied set. Calls to
cpuset_setdomain() tolerate small sets with no
The supplied mask should have a size of
setsize bytes. This size is usually provided by
sizeof(mask) which is ultimately determined
by the value of
DOMAINSET_SETSIZE as defined in
cpuset_getdomain() retrieves the mask and
policy from the object specified by level,
which and id and stores it in
the space provided by mask and
Valid policy values are as follows:
cpuset_setdomain() attempts to set the
mask and policy for the object specified by level,
which and id to the values in
mask and policy.
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.
The following error codes may be set in errno:
- Memory is allocated on a round-robin basis by cycling through each domain
- Memory is allocated on the domain local to the CPU the requesting thread
is running on. Failure to allocate from this domain will fallback to
- Memory is allocated preferentially from the single domain specified in the
mask. If memory is unavailable the domains listed in the parent cpuset
will be visited in a round-robin order.
- The level or which argument
was not a valid value.
- The mask or policy argument
specified when calling
cpuset_setdomain() was not
a valid value.
cpuset_setdomain() call would leave a thread
without a valid CPU to run on because the set does not overlap with the
thread's anonymous mask.
- The mask pointer passed was invalid.
- The object specified by the id and
which arguments could not be found.
- The domainsetsize was either preposterously large or
smaller than the kernel set size.
- The calling process did not have the credentials required to complete the
- The calling process attempted to act on a process other than itself, while
in capability mode. See
cpuset_getdomain family of system calls first
appeared in FreeBSD 12.0.