NAME
pset_assign — change processor set assignment
SYNOPSIS
#include <sys/pset.h>
int pset_assign(
psetid_t pset,
spu_t spu,
psetid_t *opset);
DESCRIPTION
The
pset_assign()
function assigns the processor
spu
to the processor set
pset,
removing the processor
spu
from its current processor set.
A processor may not belong to more than one processor set at any given
time. If
opset
is not NULL, it contains the processor set ID of
the previously assigned processor set upon successful operation.
A superuser, a PRIV_PSET privilege user, or a user with WRITE
permissions on the processor sets may change the
processor set assignment for a processor using
pset_assign()
function. A user other than superuser or without PRIV_PSET privileges must have
WRITE permissions in both processor sets to make the processor reassignment,
unless the target processor set is the system default processor set.
That is,
only a superuser or a PRIV_PSET privilege user may move a processor out
of the system default processor set.
Currently, processor 0 cannot be reassigned
to another processor set from the system default processor set. The
system default processor set is never empty.
If
pset
is
PS_DEFAULT
or
PS_NONE,
the processor
spu
is assigned to the system default processor set.
If
pset
is
PS_QUERY,
the processor's assignment is not changed, but
the current processor set ID of processor
spu
is returned in
opset.
No superuser access or WRITE permission is needed for
PS_QUERY
operation.
If there are threads or processes with binding to the processor
spu
(in its old processor set),
the binding of affected threads and processes is changed to another processor
in that processor set. If
spu
is the last processor in the locality domain that contributes to its current
processor set and there are threads or processes with binding to the
locality domain, their binding is changed to another locality domain
in the processor set. See
mpctl(2)
for binding to processors and locality domains.
If
spu
is the last processor in its current processor set, the
behavior of
pset_assign()
is dependent on the value of the
PSET_ATTR_LASTSPU
attribute. The following attribute values are defined for this attribute:
- PSET_ATTRVAL_DFLTPSET
Assign the processor to the specified processor
set, and migrate all threads and processes to
the system default processor set,
PS_DEFAULT.
This is the default behavior.
If the threads and processes being migrated to the system default
processor set
(pset)
have binding to processor or locality domain, their binding is reassigned to
another processor or locality domain in the system default processor set.
- PSET_ATTRVAL_FAIL
Make the request fail if there are active threads
and processes assigned to the processor set.
EXAMPLE
Reassign
spu
from its current processor set to
new_pset,
and retrieve the current processor set in
old_pset.
#include <sys/pset.h>
spu_t spu;
psetid_t new_pset, old_pset;
int ret;
/*
* Initialize spu and new_pset first.
* spu identifies the processor to be reassigned, whereas
* new_pset identifies the target processor set.
*/
if ((ret = pset_assign(new_pset, spu, &old_pset)) < 0) {
perror("pset_assign");
exit(1);
}
RETURN VALUE
pset_assign
returns zero on successful completion.
Otherwise, -1 is returned and
errno
is set to indicate the error.
ERRORS
pset_assign
fails if one or more of the following is true:
- [EBUSY]
The processor set currently assigned to the processor
spu
has active threads and processes, and the processor set attributes
do not allow this operation.
- [EFAULT]
The memory location pointed to by
opset
is not writable by the user.
- [EINTR]
The operation was interrupted.
- [EINVAL]
The processor
spu
or
processor set
pset
is not valid.
- [EINVAL]
The
spu
is not enabled.
- [EINVAL]
The memory location pointed to by
opset
is NULL, and the PS_QUERY operation is requested.
- [ENOSYS]
The processor set functionality is not supported by the
underlying HP-UX version.
- [EPERM]
The user does not have necessary permissions to assign
spu
to
pset.
Printable version
