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man pages section 2: System Calls

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Updated: Wednesday, July 27, 2022



pset_create, pset_destroy, pset_assign - manage sets of processors


#include <sys/pset.h>

int pset_create(psetid_t *newpset);
int pset_destroy(psetid_t pset);
int pset_assign(psetid_t pset, processorid_t cpu, psetid_t *opset);


These functions control the creation and management of sets of processors. Psets allow a subset of the system's processors to be set aside for exclusive use by specified LWPs and processes. The binding of LWPs and processes to psets is controlled by pset_bind(2).

The pset_create() function creates an empty pset that contains no processors. On successful return, newpset will contain the ID of the new pset.

The pset_destroy() function destroys the pset, releasing its constituent processors and processes. If pset is PS_MYID, the pset to which the caller is bound is destroyed.

The pset_assign() function assigns the processor cpu to the pset. A processor that has been assigned to a pset will run only LWPs and processes that have been explicitly bound to that pset, unless another LWP requires a physical resource that is only available on that processor.

On successful return, if opset is non-null, opset will contain the pset ID of the former pset of the processor.

If pset is PS_NONE, pset_assign() releases processor cpu from its current pset.

If pset is PS_QUERY, pset_assign() makes no change to processor sets, but returns the current pset ID of processor cpu in opset.

If pset is PS_MYID, processor cpu is assigned to the pset to which the caller belongs. If the caller does not belong to a pset, processor cpu is released from its current pset.

These functions are restricted to privileged processes, except for pset_assign() when pset is PS_QUERY.

Return Values

Upon successful completion, these functions return 0. Otherwise, −1 is returned and errno is set to indicate the error.


These functions will fail if:


The processor could not be moved to the specified pset.


The location pointed to by newpset was not writable by the user, or the location pointed to by opset was not NULL and not writable by the user.


The specified processor does not exist, the specified processor is not on-line, or an invalid pset was specified.


There was insufficient space for pset_create to create a new pset.


For pset_destroy() and pset_assign(), the target pset was created by the resource pools facility. For pset_assign(), this error can also be returned if the target cpus are currently assigned or allocated to a pset created by the resource pools facility. See pool_resource_create(3POOL), or poolcfg(8) for a description of how to destroy and transfer cpus to such psets.

pset_assign() will fail if the target cpu is already transferred or assigned to a pset created by the resource pools facility.


The {PRIV_SYS_RES_CONFIG} privilege is not asserted in the effective set of the calling process.


The process received a signal while attempting the operation.


See attributes(7) for descriptions of the following attributes:

Interface Stability

See Also

p_online(2), processor_bind(2), pset_bind(2), pset_info(2), pset_getloadavg(3C), pool_resource_create(3POOL), attributes(7), privileges(7), pooladm(8), psradm(8), psrinfo(8), psrset(8)


The pset type of PS_SYSTEM is no longer supported.

Processors with LWPs bound to them using processor_bind(2) cannot be assigned to a new pset. If this is attempted, pset_assign() will fail and set errno to EBUSY.