int setpriority(int which, id_t who, int value);
Specifies the type of target. Can be one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER.
Is the target of the
setpriority()request; a process ID, process group ID, or user ID, respectively, depending on the value of which. A value of 0 indicates that the target is the current process, process group, or user.
Is the new nice value for the process. Values in the range [-NZERO,(NZERO-1)] are valid; values outside that range are silently clipped to this range.
A request was made to change the nice value to a lower numeric value and the current process does not have appropriate privilege.
The value of the which parameter was not recognized, or the value of the who parameter is not a valid process ID, process group ID or user ID.
The value of the which or who parameter is not currently supported.
A process was located, but neither the real nor effective user ID of the executing process match the effective user ID of the process whose nice value is to be changed.
No process could be locating using the which and who parameter values specified.
UNIX 98, with exceptions.
UNIX 98 documentation refers to NZERO as the default nice value, and then states that the value parameter is interpreted as (value + NZERO). This is confusing, and somewhat contradictory with standard UNIX behavior. The NuTCRACKER Platform implementation uses values of -NZERO to NZERO-1, which is the same thing. NZERO is defined as 20 in <limits.h>.
The PRIO_PGRP and PRIO_USER values for
which are not currently supported; if either value is
When PRIO_PROCESS is specified for which, only 0
or the return value of
The NuTCRACKER Platform does not restrict a process from lowering its nice value (that is, raising its priority), as most UNIX platforms do. This is in keeping with the way the underlying Win32 APIs are implemented.
The following table shows the
mapping between nice values and Win32 priorities. Refer to the
Win32 documentation for
|nice value||Win32 Priority|
|-20 to -16||THREAD_PRIORITY_HIGHEST|
|-15 to -6||THREAD_PRIORITY_ABOVE_NORMAL|
|-5 to +4||THREAD_PRIORITY_NORMAL|
|+5 to +14||THREAD_PRIORITY_BELOW_NORMAL|
|+15 to +19||THREAD_PRIORITY_LOWEST|
This API results in a call to the Windows function
Do not adjust the Windows Priority Class with the Windows
SetPriorityClass()API. This can cause NuTCRACKER Platform core data structures to become corrupt and unusable or other undesirable results; all of which could result in the system hanging or worse.
PTC MKS Toolkit for Professional Developers
PTC MKS Toolkit for Professional Developers 64-Bit Edition
PTC MKS Toolkit for Enterprise Developers
PTC MKS Toolkit for Enterprise Developers 64-Bit Edition
execl(), execle(), execlp(), execlpe(), execv(), execve(), execvp(), execvpe(), fork(), getpriority(), nice()
PTC MKS Toolkit 10.4 Documentation Build 39.