forked from Imagelibrary/rtems
9b4422a251
Script does what is expected and tries to do it as smartly as possible. + remove occurrences of two blank comment lines next to each other after Id string line removed. + remove entire comment blocks which only exited to contain CVS Ids + If the processing left a blank line at the top of a file, it was removed.
217 lines
4.5 KiB
Perl
217 lines
4.5 KiB
Perl
@c
|
|
@c COPYRIGHT (c) 1988-2002.
|
|
@c On-Line Applications Research Corporation (OAR).
|
|
@c All rights reserved.
|
|
|
|
@chapter Scheduler Manager
|
|
|
|
@section Introduction
|
|
|
|
The scheduler manager ...
|
|
|
|
The directives provided by the scheduler manager are:
|
|
|
|
@itemize @bullet
|
|
@item @code{sched_get_priority_min} - Get Minimum Priority Value
|
|
@item @code{sched_get_priority_max} - Get Maximum Priority Value
|
|
@item @code{sched_rr_get_interval} - Get Timeslicing Quantum
|
|
@item @code{sched_yield} - Yield the Processor
|
|
@end itemize
|
|
|
|
@section Background
|
|
|
|
@subsection Priority
|
|
|
|
In the RTEMS implementation of the POSIX API, the priorities range from
|
|
the low priority of @code{sched_get_priority_min()} to the highest priority of
|
|
@code{sched_get_priority_max()}. Numerically higher values represent higher
|
|
priorities.
|
|
|
|
@subsection Scheduling Policies
|
|
|
|
The following scheduling policies are available:
|
|
|
|
@table @b
|
|
@item SCHED_FIFO
|
|
Priority-based, preemptive scheduling with no timeslicing. This is equivalent
|
|
to what is called "manual round-robin" scheduling.
|
|
|
|
@item SCHED_RR
|
|
Priority-based, preemptive scheduling with timeslicing. Time quantums are
|
|
maintained on a per-thread basis and are not reset at each context switch.
|
|
Thus, a thread which is preempted and subsequently resumes execution will
|
|
attempt to complete the unused portion of its time quantum.
|
|
|
|
@item SCHED_OTHER
|
|
Priority-based, preemptive scheduling with timeslicing. Time quantums are
|
|
maintained on a per-thread basis and are reset at each context switch.
|
|
|
|
@item SCHED_SPORADIC
|
|
Priority-based, preemptive scheduling utilizing three additional parameters:
|
|
budget, replenishment period, and low priority. Under this policy, the
|
|
thread is allowed to execute for "budget" amount of time before its priority
|
|
is lowered to "low priority". At the end of each replenishment period,
|
|
the thread resumes its initial priority and has its budget replenished.
|
|
|
|
@end table
|
|
|
|
@section Operations
|
|
|
|
There is currently no text in this section.
|
|
|
|
@section Directives
|
|
|
|
This section details the scheduler manager's directives.
|
|
A subsection is dedicated to each of this manager's directives
|
|
and describes the calling sequence, related constants, usage,
|
|
and status codes.
|
|
|
|
@c
|
|
@c
|
|
@c
|
|
@page
|
|
@subsection sched_get_priority_min - Get Minimum Priority Value
|
|
|
|
@findex sched_get_priority_min
|
|
@cindex get minimum priority value
|
|
|
|
@subheading CALLING SEQUENCE:
|
|
|
|
@example
|
|
#include <sched.h>
|
|
|
|
int sched_get_priority_min(
|
|
int policy
|
|
);
|
|
@end example
|
|
|
|
@subheading STATUS CODES:
|
|
|
|
On error, this routine returns -1 and sets errno to one of the following:
|
|
|
|
@table @b
|
|
@item EINVAL
|
|
The indicated policy is invalid.
|
|
|
|
@end table
|
|
|
|
@subheading DESCRIPTION:
|
|
|
|
This routine return the minimum (numerically and logically lowest) priority
|
|
for the specified @code{policy}.
|
|
|
|
@subheading NOTES:
|
|
|
|
NONE
|
|
|
|
@c
|
|
@c
|
|
@c
|
|
@page
|
|
@subsection sched_get_priority_max - Get Maximum Priority Value
|
|
|
|
@findex sched_get_priority_max
|
|
@cindex get maximum priority value
|
|
|
|
@subheading CALLING SEQUENCE:
|
|
|
|
@example
|
|
#include <sched.h>
|
|
|
|
int sched_get_priority_max(
|
|
int policy
|
|
);
|
|
@end example
|
|
|
|
@subheading STATUS CODES:
|
|
|
|
On error, this routine returns -1 and sets errno to one of the following:
|
|
|
|
@table @b
|
|
@item EINVAL
|
|
The indicated policy is invalid.
|
|
|
|
@end table
|
|
|
|
@subheading DESCRIPTION:
|
|
|
|
This routine return the maximum (numerically and logically highest) priority
|
|
for the specified @code{policy}.
|
|
|
|
@subheading NOTES:
|
|
|
|
NONE
|
|
|
|
@c
|
|
@c
|
|
@c
|
|
@page
|
|
@subsection sched_rr_get_interval - Get Timeslicing Quantum
|
|
|
|
@findex sched_rr_get_interval
|
|
@cindex get timeslicing quantum
|
|
|
|
@subheading CALLING SEQUENCE:
|
|
|
|
@example
|
|
#include <sched.h>
|
|
|
|
int sched_rr_get_interval(
|
|
pid_t pid,
|
|
struct timespec *interval
|
|
);
|
|
@end example
|
|
|
|
@subheading STATUS CODES:
|
|
|
|
On error, this routine returns -1 and sets errno to one of the following:
|
|
|
|
@table @b
|
|
@item ESRCH
|
|
The indicated process id is invalid.
|
|
|
|
@item EINVAL
|
|
The specified interval pointer parameter is invalid.
|
|
|
|
@end table
|
|
|
|
@subheading DESCRIPTION:
|
|
|
|
This routine returns the length of the timeslice quantum in the
|
|
@code{interval} parameter for the specified @code{pid}.
|
|
|
|
@subheading NOTES:
|
|
|
|
The @code{pid} argument should be 0 to indicate the calling process.
|
|
|
|
@c
|
|
@c
|
|
@c
|
|
@page
|
|
@subsection sched_yield - Yield the Processor
|
|
|
|
@findex sched_yield
|
|
@cindex yield the processor
|
|
|
|
@subheading CALLING SEQUENCE:
|
|
|
|
@example
|
|
#include <sched.h>
|
|
|
|
int sched_yield( void );
|
|
@end example
|
|
|
|
@subheading STATUS CODES:
|
|
|
|
This routine always returns zero to indicate success.
|
|
|
|
@subheading DESCRIPTION:
|
|
|
|
This call forces the calling thread to yield the processor to another
|
|
thread. Normally this is used to implement voluntary round-robin
|
|
task scheduling.
|
|
|
|
@subheading NOTES:
|
|
|
|
NONE
|