table of contents
|CPUSET_GETAFFINITY(2)||System Calls Manual||CPUSET_GETAFFINITY(2)|
cpuset_setaffinity — manage
Standard C Library (libc, -lc)
which, id_t id,
which, id_t id,
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
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
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
even if the result set would fit within the user supplied set. Calls to
cpuset_setaffinity() 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
CPU_SETSIZE as defined in
retrieves the mask from the object specified by level,
which and id and stores it in
the space provided by mask.
attempts to set the mask for the object specified by
level, which and
id to the value in mask.
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:
- The level or which argument was not a valid value.
- The mask argument specified when calling
cpuset_setaffinity() was not a valid value.
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.
- The mask pointer passed was invalid.
- The object specified by the id and which arguments could not be found.
- The cpusetsize was either preposterously large or smaller than the kernel set size.
- The calling process did not have the credentials required to complete the operation.
cpuset(1), cpuset(2), cpuset_getid(2), cpuset_setid(2), pthread_affinity_np(3), pthread_attr_affinity_np(3), cpuset(9)
cpuset_getaffinity family of system
calls first appeared in FreeBSD 7.1.
Jeffrey Roberson <jeff@FreeBSD.org>
|June 2, 2016||Debian|