table of contents
CPUSET(2) | System Calls Manual | CPUSET(2) |
NAME¶
cpuset_getaffinity, cpuset_setaffinity — manage CPU affinityLIBRARY¶
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 ofCPU_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(2) 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.
- [
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), CPU_SET(3), 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⟩
January 8, 2010 | Debian |