focal (2) cpuset_getaffinity.2freebsd.gz

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.

     [ECAPMODE]         The calling process attempted to act on a process other than itself, while in capability
                        mode.  See capsicum(4).

SEE ALSO

     capsicum(4), cpuset(1), cpuset(2), cpuset_getid(2), cpuset_setid(2), cpuset_getdomain(2),
     cpuset_setdomain(2), pthread_affinity_np(3), pthread_attr_affinity_np(3), cpuset(9)

HISTORY

     The cpuset_getaffinity family of system calls first appeared in FreeBSD 7.1.

AUTHORS

     Jeffrey Roberson <jeff@FreeBSD.org>