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RTPRIO (2) | System calls | Unix Manual Pages | :man

NAME

rtprio - examine or modify a process realtime or idle priority

CONTENTS

Library
Synopsis
Description
Return Values
Errors
See Also
Authors

LIBRARY


.Lb libc

SYNOPSIS


.In sys/types.h
.In sys/rtprio.h int rtprio "int function" "pid_t pid" "struct rtprio *rtp"

DESCRIPTION

The rtprio system call is used to lookup or change the realtime or idle priority of a process.

The function argument specifies the operation to be performed. RTP_LOOKUP to lookup the current priority, and RTP_SET to set the priority. The pid argument specifies the process to be used, 0 for the current process.

The *rtp argument is a pointer to a struct rtprio which is used to specify the priority and priority type. This structure has the following form:
struct rtprio {
u_short type;
u_short prio;
};

The value of the type field may be RTP_PRIO_REALTIME for realtime priorities, RTP_PRIO_NORMAL for normal priorities, and RTP_PRIO_IDLE for idle priorities. The priority specified by the prio field ranges between 0 and RTP_PRIO_MAX (usually 31). 0 is the highest possible priority.

Realtime and idle priority is inherited through fork() and exec().

A realtime process can only be preempted by a process of equal or higher priority, or by an interrupt; idle priority processes will run only when no other real/normal priority process is runnable. Higher real/idle priority processes preempt lower real/idle priority processes. Processes of equal real/idle priority are run round-robin.

RETURN VALUES


.Rv -std rtprio

ERRORS

The rtprio system call will fail if
[EINVAL]
The specified prio was out of range.
[EPERM]
The calling process is not allowed to set the realtime priority. Only root is allowed to change the realtime priority of any process, and non-root may only change the idle priority of the current process.
[ESRCH]
The specified process was not found.

SEE ALSO

nice(1), ps(1), rtprio(1), setpriority(2), nice(3), renice(8)

AUTHORS


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