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AIX Version 4.3 Base Operating System and Extensions Technical Reference, Volume 2
setpri Subroutine
Purpose
Sets a process scheduling priority to a constant value.
Library
Standard C Library (libc.a)
Syntax
#include <sys/sched.h>
int setpri (ProcessID, Priority)
pid_t ProcessID;
int Priority;
Description
The setpri subroutine sets the scheduling priority of
all threads in a process to be a constant. All threads have their scheduling policies changed to SCHED_RR.
A process nice value and CPU usage can no longer be used to determine a process scheduling priority. Only processes that have root user authority can set a process scheduling priority to a constant.
Parameters
ProcessID |
Specifies the process ID. If this value is 0 then the current process scheduling priority is set to a constant. |
Priority |
Specifies the scheduling priority for the process. A lower number value designates a higher scheduling priority. The Priority parameter must be in the range PRIORITY_MIN < Priority < PRIORITY_MAX. (See the sys/sched.h file.) |
Return Values
Upon successful completion, the setpri subroutine returns the former scheduling priority of the process just changed. Otherwise, a value of -1 is returned and the errno global variable is set to indicate the error.
Error Codes
The setpri subroutine is unsuccessful if one or more of the following is true:
EINVAL |
The priority specified by the Priority parameter is outside the range of acceptable priorities. |
EPERM |
The process executing the setpri subroutine call does not have root user authority. |
ESRCH |
No process can be found corresponding to that specified by the ProcessID parameter. |
Implementation Specifics
This subroutine is part of Base Operating System (BOS) Runtime.
Related Information
The getpri subroutine.
Performance-Related Subroutines in AIX Versions 3.2 and 4 Performance Tuning Guide.
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