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man pages section 2: System Calls

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Updated: Wednesday, July 27, 2022



priocntlset - generalized process scheduler control


#include <sys/types.h>
#include <sys/procset.h>
#include <sys/priocntl.h>
#include <sys/rtpriocntl.h>
#include <sys/tspriocntl.h>
#include <sys/iapriocntl.h>
#include <sys/fsspriocntl.h>
#include <sys/fxpriocntl.h>

long priocntlset(procset_t *psp, int cmd, /* arg */ ...);


The priocntlset() function changes the scheduling properties of running processes. priocntlset() has the same functions as the priocntl() function, but a more general way of specifying the set of processes whose scheduling properties are to be changed, which includes specifying LWPs of processes other than the calling process.

cmd specifies the function to be performed. arg is a pointer to a structure whose type depends on cmd. See priocntl(2) for the valid values of cmd and the corresponding arg structures.

psp is a pointer to a procset structure, which priocntlset() uses to specify the set of processes whose scheduling properties are to be changed. The procset structure contains the following members:

idop_t    p_op;        /* operator connecting left/right sets */
idtype_t  p_lidtype;   /* left set ID type */
id_t      p_lid;       /* left set ID */
idtype_t  p_ridtype;   /* right set ID type */
id_t      p_rid;       /* right set ID */

The p_lidtype and p_lid members specify the ID type and ID of one (“left”) set of processes; the p_ridtype and p_rid members specify the ID type and ID of a second (“right”) set of processes. ID types and IDs are specified just as for the priocntl() function. The p_op member specifies the operation to be performed on the two sets of processes to get the set of processes the function is to apply to. The valid values for p_op and the processes they specify are:


Set difference: processes in left set and not in right set.


Set intersection: processes in both left and right sets.


Set union: processes in either left or right sets or both.


Set exclusive-or: processes in left or right set but not in both.

The following macro, which is defined in <procset.h>, offers a convenient way to initialize a procset structure:

#define  setprocset(psp, op, ltype, lid, rtype, rid) \
(psp)->p_op       = (op), \
(psp)->p_lidtype  = (ltype), \
(psp)->p_lid      = (lid), \
(psp)->p_ridtype  = (rtype), \
(psp)->p_rid      = (rid),

Return Values

Unless otherwise noted above, priocntlset() returns 0 on success. Otherwise, it returns −1 and sets errno to indicate the error.


The priocntlset() function will fail if:


An attempt to change the class of a process failed because of insufficient resources other than memory (for example, class-specific kernel data structures).


One of the arguments points to an illegal address.


The argument cmd was invalid, an invalid or unconfigured class was specified, or one of the parameters specified was invalid.


An attempt to change the class of a process failed because of insufficient memory.


The {PRIV_PROC_PRIOCNTL} privilege is not asserted in the effective set of the calling LWP.

The calling LWP does not have sufficient privileges to affect the target LWP.


The requested time quantum is out of range.


None of the specified processes exist.

See Also

priocntl(1), priocntl(2)