forked from Imagelibrary/rtems
4ebb4862d2
automatically generated. Removed any attempts to link across chapter boundaries since the manual is incomplete.
174 lines
3.5 KiB
Perl
174 lines
3.5 KiB
Perl
@c
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@c COPYRIGHT (c) 1988-1998.
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@c On-Line Applications Research Corporation (OAR).
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@c All rights reserved.
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@c
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@c $Id$
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@c
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@chapter Scheduler Manager
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@section Introduction
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The scheduler manager ...
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The directives provided by the scheduler manager are:
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@itemize @bullet
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@item @code{sched_get_priority_min} -
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@item @code{sched_get_priority_max} -
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@item @code{sched_rr_get_interval} -
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@item @code{sched_yield} -
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@end itemize
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@section Background
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@subsection Priority
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In the RTEMS implementation of the POSIX API, the priorities range from
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the low priority of sched_get_priority_min() to the highest priority of
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sched_get_priority_max(). Numerically higher values represent higher
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priorities.
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@subsection Scheduling Policies
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The following scheduling policies are available:
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@table @b
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@item SCHED_FIFO
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Priority-based, preemptive scheduling with no timeslicing. This is equivalent
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to what is called "manual round-robin" scheduling.
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@item SCHED_RR
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Priority-based, preemptive scheduling with timeslicing. Time quantums are
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maintained on a per-thread basis and are not reset at each context switch.
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Thus, a thread which is preempted and subsequently resumes execution will
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attempt to complete the unused portion of its time quantum.
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@item SCHED_OTHER
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Priority-based, preemptive scheduling with timeslicing. Time quantums are
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maintained on a per-thread basis and are reset at each context switch.
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@item SCHED_SPORADIC
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Priority-based, preemptive scheduling utilizing three additional parameters:
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budget, replenishment period, and low priority. Under this policy, the
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thread is allowed to execute for "budget" amount of time before its priority
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is lowered to "low priority". At the end of each replenishment period,
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the thread resumes its initial priority and has its budget replenished.
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@end table
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@section Operations
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@section Directives
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This section details the scheduler manager's directives.
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A subsection is dedicated to each of this manager's directives
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and describes the calling sequence, related constants, usage,
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and status codes.
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@page
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@subsection sched_get_priority_min
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@subheading CALLING SEQUENCE:
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@example
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#include <sched.h>
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int sched_get_priority_min(
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int policy
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);
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@end example
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@subheading STATUS CODES:
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On error, this routine returns -1 and sets errno to one of the following:
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@table @b
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@item EINVAL
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The indicated policy is invalid.
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@end table
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@subheading DESCRIPTION:
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@subheading NOTES:
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@page
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@subsection sched_get_priority_max
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@subheading CALLING SEQUENCE:
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@example
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#include <sched.h>
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int sched_get_priority_max(
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int policy
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);
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@end example
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@subheading STATUS CODES:
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On error, this routine returns -1 and sets errno to one of the following:
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@table @b
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@item EINVAL
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The indicated policy is invalid.
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@end table
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@subheading DESCRIPTION:
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@subheading NOTES:
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@page
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@subsection sched_rr_get_interval
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@subheading CALLING SEQUENCE:
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@example
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#include <sched.h>
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int sched_rr_get_interval(
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pid_t pid,
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struct timespec *interval
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);
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@end example
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@subheading STATUS CODES:
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On error, this routine returns -1 and sets errno to one of the following:
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@table @b
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@item ESRCH
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The indicated process id is invalid.
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@item EINVAL
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The specified interval pointer parameter is invalid.
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@end table
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@subheading DESCRIPTION:
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@subheading NOTES:
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@page
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@subsection sched_yield
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@subheading CALLING SEQUENCE:
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@example
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#include <sched.h>
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int sched_yield( void );
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@end example
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@subheading STATUS CODES:
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This routine always returns zero to indicate success.
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@subheading DESCRIPTION:
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@subheading NOTES:
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