mirror of
https://git.rtems.org/rtems-docs/
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599 lines
18 KiB
ReStructuredText
599 lines
18 KiB
ReStructuredText
.. SPDX-License-Identifier: CC-BY-SA-4.0
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.. Copyright (C) 2020 embedded brains GmbH (http://www.embedded-brains.de)
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.. Copyright (C) 2010 Gedare Bloom
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.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)
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.. This file is part of the RTEMS quality process and was automatically
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.. generated. If you find something that needs to be fixed or
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.. worded better please post a report or patch to an RTEMS mailing list
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.. or raise a bug report:
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..
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.. https://www.rtems.org/bugs.html
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..
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.. For information on updating and regenerating please refer to the How-To
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.. section in the Software Requirements Engineering chapter of the
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.. RTEMS Software Engineering manual. The manual is provided as a part of
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.. a release. For development sources please refer to the online
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.. documentation at:
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..
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.. https://docs.rtems.org
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.. Generated from spec:/acfg/if/group-schedgeneral
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General Scheduler Configuration
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===============================
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This section describes configuration options related to selecting a
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scheduling algorithm for an application. A scheduler configuration is optional
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and only necessary in very specific circumstances. A normal application
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configuration does not need any of the configuration options described in this
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section.
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By default, the :ref:`SchedulerPriority`
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algorithm is used in uniprocessor configurations. In case SMP is enabled and
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the configured maximum processors
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(:ref:`CONFIGURE_MAXIMUM_PROCESSORS`) is greater
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than one, then the
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:ref:`SchedulerSMPEDF`
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is selected as the default scheduler algorithm.
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For the schedulers provided by RTEMS (see :ref:`RTEMSAPIClassicScheduler`), the
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configuration is straightforward. All that is required is to define the
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configuration option which specifies which scheduler you want for in your
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application.
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The pluggable scheduler interface also enables the user to provide their own
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scheduling algorithm. If you choose to do this, you must define multiple
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configuration option.
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.. Generated from spec:/acfg/if/cbs-max-servers
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.. index:: CONFIGURE_CBS_MAXIMUM_SERVERS
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.. _CONFIGURE_CBS_MAXIMUM_SERVERS:
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CONFIGURE_CBS_MAXIMUM_SERVERS
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-----------------------------
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CONSTANT:
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``CONFIGURE_CBS_MAXIMUM_SERVERS``
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OPTION TYPE:
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This configuration option is an integer define.
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DEFAULT VALUE:
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The default value is :ref:`CONFIGURE_MAXIMUM_TASKS`.
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VALUE CONSTRAINTS:
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The value of this configuration option shall satisfy all of the following
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constraints:
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* It shall be greater than or equal to 0.
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* It shall be less than or equal to `SIZE_MAX <https://en.cppreference.com/w/c/types/limits>`_.
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* It shall be less than or equal to a
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BSP-specific and application-specific value which depends on the size of the
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memory available to the application.
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DESCRIPTION:
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The value of this configuration option defines the maximum number Constant
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Bandwidth Servers that can be concurrently active.
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NOTES:
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This configuration option is only evaluated if the configuration option
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:ref:`CONFIGURE_SCHEDULER_CBS` is defined.
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.. Generated from spec:/acfg/if/max-priority
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.. index:: CONFIGURE_MAXIMUM_PRIORITY
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.. index:: maximum priority
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.. index:: number of priority levels
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.. _CONFIGURE_MAXIMUM_PRIORITY:
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CONFIGURE_MAXIMUM_PRIORITY
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--------------------------
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CONSTANT:
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``CONFIGURE_MAXIMUM_PRIORITY``
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OPTION TYPE:
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This configuration option is an integer define.
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DEFAULT VALUE:
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The default value is 255.
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VALUE CONSTRAINTS:
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The value of this configuration option shall be
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an element of {3, 7, 31, 63, 127, 255}.
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DESCRIPTION:
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For the following schedulers
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* :ref:`SchedulerPriority`, which is the default in uniprocessor
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configurations and can be configured through the
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:ref:`CONFIGURE_SCHEDULER_PRIORITY` configuration option,
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* :ref:`SchedulerSMPPriority` which can be configured through the
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:ref:`CONFIGURE_SCHEDULER_PRIORITY_SMP` configuration option, and
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* :ref:`SchedulerSMPPriorityAffinity` which can be configured through the
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:ref:`CONFIGURE_SCHEDULER_PRIORITY_AFFINITY_SMP` configuration option
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this configuration option specifies the maximum numeric priority of any task
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for these schedulers and one less that the number of priority levels for
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these schedulers. For all other schedulers provided by RTEMS, this
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configuration option has no effect.
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NOTES:
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The numerically greatest priority is the logically lowest priority in the
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system and will thus be used by the IDLE task.
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Priority zero is reserved for internal use by RTEMS and is not available to
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applications.
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Reducing the number of priorities through this configuration option reduces
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the amount of memory allocated by the schedulers listed above. These
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schedulers use a chain control structure per priority and this structure
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consists of three pointers. On a 32-bit architecture, the allocated memory
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is 12 bytes * (``CONFIGURE_MAXIMUM_PRIORITY`` + 1), e.g. 3072 bytes for 256
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priority levels (default), 48 bytes for 4 priority levels
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(``CONFIGURE_MAXIMUM_PRIORITY == 3``).
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The default value is 255, because RTEMS shall support 256 priority levels to
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be compliant with various standards. These priorities range from 0 to 255.
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.. Generated from spec:/acfg/if/scheduler-assignments
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.. index:: CONFIGURE_SCHEDULER_ASSIGNMENTS
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.. _CONFIGURE_SCHEDULER_ASSIGNMENTS:
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CONFIGURE_SCHEDULER_ASSIGNMENTS
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-------------------------------
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CONSTANT:
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``CONFIGURE_SCHEDULER_ASSIGNMENTS``
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OPTION TYPE:
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This configuration option is an initializer define.
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DEFAULT VALUE:
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The default value of this configuration option is computed so that the
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default scheduler is assigned to each configured processor (up to 32).
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VALUE CONSTRAINTS:
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The value of this configuration option shall satisfy all of the following
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constraints:
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* It shall be a list of the following
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macros:
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* ``RTEMS_SCHEDULER_ASSIGN( processor_index, attributes )``
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* ``RTEMS_SCHEDULER_ASSIGN_NO_SCHEDULER``
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* It shall be a list of exactly
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:ref:`CONFIGURE_MAXIMUM_PROCESSORS` elements.
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DESCRIPTION:
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The value of this configuration option is used to initialize the initial
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scheduler to processor assignments.
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NOTES:
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This configuration option is only evaluated in SMP configurations.
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This is an advanced configuration option, see
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:ref:`ConfigurationSchedulersClustered`.
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.. Generated from spec:/acfg/if/scheduler-cbs
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.. index:: CONFIGURE_SCHEDULER_CBS
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.. _CONFIGURE_SCHEDULER_CBS:
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CONFIGURE_SCHEDULER_CBS
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-----------------------
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CONSTANT:
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``CONFIGURE_SCHEDULER_CBS``
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OPTION TYPE:
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This configuration option is a boolean feature define.
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DEFAULT CONFIGURATION:
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If this configuration option is undefined, then the described feature is not
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enabled.
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DESCRIPTION:
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In case this configuration option is defined, then
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:ref:`SchedulerCBS`
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algorithm is made available to the application.
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NOTES:
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This scheduler configuration option is an advanced configuration option.
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Think twice before you use it.
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In case no explicit :ref:`ConfigurationSchedulersClustered`
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is present, then it is used as the scheduler for exactly one processor.
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.. Generated from spec:/acfg/if/scheduler-edf
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.. index:: CONFIGURE_SCHEDULER_EDF
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.. _CONFIGURE_SCHEDULER_EDF:
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CONFIGURE_SCHEDULER_EDF
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-----------------------
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CONSTANT:
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``CONFIGURE_SCHEDULER_EDF``
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OPTION TYPE:
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This configuration option is a boolean feature define.
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DEFAULT CONFIGURATION:
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If this configuration option is undefined, then the described feature is not
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enabled.
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DESCRIPTION:
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In case this configuration option is defined, then
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:ref:`SchedulerEDF`
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algorithm is made available to the application.
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NOTES:
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This scheduler configuration option is an advanced configuration option.
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Think twice before you use it.
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In case no explicit :ref:`ConfigurationSchedulersClustered`
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is present, then it is used as the scheduler for exactly one processor.
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.. Generated from spec:/acfg/if/scheduler-edf-smp
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.. index:: CONFIGURE_SCHEDULER_EDF_SMP
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.. _CONFIGURE_SCHEDULER_EDF_SMP:
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CONFIGURE_SCHEDULER_EDF_SMP
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---------------------------
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CONSTANT:
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``CONFIGURE_SCHEDULER_EDF_SMP``
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OPTION TYPE:
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This configuration option is a boolean feature define.
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DEFAULT CONFIGURATION:
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If this configuration option is undefined, then the described feature is not
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enabled.
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DESCRIPTION:
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In case this configuration option is defined, then
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:ref:`SchedulerSMPEDF`
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algorithm is made available to the application.
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NOTES:
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This scheduler configuration option is an advanced configuration option.
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Think twice before you use it.
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This scheduler algorithm is only available when RTEMS is built with SMP
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support enabled.
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In case no explicit :ref:`ConfigurationSchedulersClustered`
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is present, then it is used as the scheduler for up to 32 processors.
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This scheduler algorithm is the default in SMP configurations if
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:ref:`CONFIGURE_MAXIMUM_PROCESSORS` is
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greater than one.
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.. Generated from spec:/acfg/if/scheduler-name
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.. index:: CONFIGURE_SCHEDULER_NAME
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.. _CONFIGURE_SCHEDULER_NAME:
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CONFIGURE_SCHEDULER_NAME
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------------------------
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CONSTANT:
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``CONFIGURE_SCHEDULER_NAME``
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OPTION TYPE:
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This configuration option is an integer define.
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DEFAULT VALUE:
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The default value is
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* ``"MEDF"`` for the :ref:`SchedulerSMPEDF`,
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* ``"MPA "`` for the :ref:`SchedulerSMPPriorityAffinity`,
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* ``"MPD "`` for the :ref:`SchedulerSMPPriority`,
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* ``"MPS "`` for the :ref:`SchedulerSMPPrioritySimple`,
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* ``"UCBS"`` for the :ref:`SchedulerCBS`,
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* ``"UEDF"`` for the :ref:`SchedulerEDF`,
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* ``"UPD "`` for the :ref:`SchedulerPriority`, and
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* ``"UPS "`` for the :ref:`SchedulerPrioritySimple`.
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VALUE CONSTRAINTS:
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The value of this configuration option shall be a valid integer of type
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:c:type:`rtems_name`.
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DESCRIPTION:
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The value of this configuration option defines the name of the default
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scheduler.
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NOTES:
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This scheduler configuration option is an advanced configuration option.
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Think twice before you use it.
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Schedulers can be identified via :c:func:`rtems_scheduler_ident`.
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Use :c:func:`rtems_build_name` to define the scheduler name.
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.. Generated from spec:/acfg/if/scheduler-priority
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.. index:: CONFIGURE_SCHEDULER_PRIORITY
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.. _CONFIGURE_SCHEDULER_PRIORITY:
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CONFIGURE_SCHEDULER_PRIORITY
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----------------------------
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CONSTANT:
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``CONFIGURE_SCHEDULER_PRIORITY``
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OPTION TYPE:
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This configuration option is a boolean feature define.
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DEFAULT CONFIGURATION:
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If this configuration option is undefined, then the described feature is not
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enabled.
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DESCRIPTION:
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In case this configuration option is defined, then
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:ref:`SchedulerPriority`
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algorithm is made available to the application.
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NOTES:
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This scheduler configuration option is an advanced configuration option.
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Think twice before you use it.
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In case no explicit :ref:`ConfigurationSchedulersClustered`
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is present, then it is used as the scheduler for exactly one processor.
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This scheduler algorithm is the default when
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:ref:`CONFIGURE_MAXIMUM_PROCESSORS` is
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exactly one.
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The memory allocated for this scheduler depends on the
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:ref:`CONFIGURE_MAXIMUM_PRIORITY` configuration option.
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.. Generated from spec:/acfg/if/scheduler-priority-affinity-smp
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.. index:: CONFIGURE_SCHEDULER_PRIORITY_AFFINITY_SMP
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.. _CONFIGURE_SCHEDULER_PRIORITY_AFFINITY_SMP:
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CONFIGURE_SCHEDULER_PRIORITY_AFFINITY_SMP
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-----------------------------------------
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CONSTANT:
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``CONFIGURE_SCHEDULER_PRIORITY_AFFINITY_SMP``
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OPTION TYPE:
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This configuration option is a boolean feature define.
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DEFAULT CONFIGURATION:
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If this configuration option is undefined, then the described feature is not
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enabled.
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DESCRIPTION:
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In case this configuration option is defined, then
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:ref:`SchedulerSMPPriorityAffinity`
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algorithm is made available to the application.
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NOTES:
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This scheduler configuration option is an advanced configuration option.
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Think twice before you use it.
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This scheduler algorithm is only available when RTEMS is built with SMP
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support enabled.
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In case no explicit :ref:`ConfigurationSchedulersClustered`
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is present, then it is used as the scheduler for up to 32 processors.
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The memory allocated for this scheduler depends on the
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:ref:`CONFIGURE_MAXIMUM_PRIORITY` configuration option.
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.. Generated from spec:/acfg/if/scheduler-priority-smp
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.. index:: CONFIGURE_SCHEDULER_PRIORITY_SMP
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.. _CONFIGURE_SCHEDULER_PRIORITY_SMP:
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CONFIGURE_SCHEDULER_PRIORITY_SMP
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--------------------------------
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CONSTANT:
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``CONFIGURE_SCHEDULER_PRIORITY_SMP``
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OPTION TYPE:
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This configuration option is a boolean feature define.
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DEFAULT CONFIGURATION:
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If this configuration option is undefined, then the described feature is not
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enabled.
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DESCRIPTION:
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In case this configuration option is defined, then
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:ref:`SchedulerSMPPriority`
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algorithm is made available to the application.
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NOTES:
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This scheduler configuration option is an advanced configuration option.
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Think twice before you use it.
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This scheduler algorithm is only available when RTEMS is built with SMP
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support enabled.
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In case no explicit :ref:`ConfigurationSchedulersClustered`
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is present, then it is used as the scheduler for up to 32 processors.
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The memory allocated for this scheduler depends on the
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:ref:`CONFIGURE_MAXIMUM_PRIORITY` configuration option.
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|
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.. Generated from spec:/acfg/if/scheduler-simple
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.. index:: CONFIGURE_SCHEDULER_SIMPLE
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.. _CONFIGURE_SCHEDULER_SIMPLE:
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CONFIGURE_SCHEDULER_SIMPLE
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--------------------------
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CONSTANT:
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``CONFIGURE_SCHEDULER_SIMPLE``
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OPTION TYPE:
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This configuration option is a boolean feature define.
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DEFAULT CONFIGURATION:
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If this configuration option is undefined, then the described feature is not
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enabled.
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DESCRIPTION:
|
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In case this configuration option is defined, then
|
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:ref:`SchedulerPrioritySimple`
|
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algorithm is made available to the application.
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NOTES:
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This scheduler configuration option is an advanced configuration option.
|
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Think twice before you use it.
|
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In case no explicit :ref:`ConfigurationSchedulersClustered`
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is present, then it is used as the scheduler for exactly one processor.
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.. Generated from spec:/acfg/if/scheduler-simple-smp
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.. index:: CONFIGURE_SCHEDULER_SIMPLE_SMP
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.. _CONFIGURE_SCHEDULER_SIMPLE_SMP:
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CONFIGURE_SCHEDULER_SIMPLE_SMP
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------------------------------
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CONSTANT:
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``CONFIGURE_SCHEDULER_SIMPLE_SMP``
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OPTION TYPE:
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This configuration option is a boolean feature define.
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DEFAULT CONFIGURATION:
|
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If this configuration option is undefined, then the described feature is not
|
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enabled.
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DESCRIPTION:
|
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In case this configuration option is defined, then
|
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:ref:`SchedulerSMPPrioritySimple`
|
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algorithm is made available to the application.
|
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application.
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|
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NOTES:
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This scheduler configuration option is an advanced configuration option.
|
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Think twice before you use it.
|
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|
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This scheduler algorithm is only available when RTEMS is built with SMP
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support enabled.
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In case no explicit :ref:`ConfigurationSchedulersClustered`
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is present, then it is used as the scheduler for up to 32 processors.
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|
|
.. Generated from spec:/acfg/if/scheduler-strong-apa
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.. index:: CONFIGURE_SCHEDULER_STRONG_APA
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.. _CONFIGURE_SCHEDULER_STRONG_APA:
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CONFIGURE_SCHEDULER_STRONG_APA
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------------------------------
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CONSTANT:
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``CONFIGURE_SCHEDULER_STRONG_APA``
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OPTION TYPE:
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This configuration option is a boolean feature define.
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DEFAULT CONFIGURATION:
|
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If this configuration option is undefined, then the described feature is not
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enabled.
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DESCRIPTION:
|
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In case this configuration option is defined, then Strong APA algorithm is
|
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made available to the application.
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NOTES:
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This scheduler configuration option is an advanced configuration option.
|
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Think twice before you use it.
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This scheduler algorithm is only available when RTEMS is built with SMP
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support enabled.
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This scheduler algorithm is not correctly implemented. Do not use it.
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|
.. Generated from spec:/acfg/if/scheduler-user
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.. index:: CONFIGURE_SCHEDULER_USER
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.. _CONFIGURE_SCHEDULER_USER:
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CONFIGURE_SCHEDULER_USER
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------------------------
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CONSTANT:
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``CONFIGURE_SCHEDULER_USER``
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|
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OPTION TYPE:
|
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This configuration option is a boolean feature define.
|
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DEFAULT CONFIGURATION:
|
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If this configuration option is undefined, then the described feature is not
|
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enabled.
|
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|
|
DESCRIPTION:
|
|
In case this configuration option is defined, then the user shall provide a
|
|
scheduler algorithm to the application.
|
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|
|
NOTES:
|
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This scheduler configuration option is an advanced configuration option.
|
|
Think twice before you use it.
|
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|
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RTEMS allows the application to provide its own task/thread scheduling
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algorithm. In order to do this, one shall define
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``CONFIGURE_SCHEDULER_USER`` to indicate the application provides its own
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scheduling algorithm. If ``CONFIGURE_SCHEDULER_USER`` is defined then the
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following additional macros shall be defined:
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* ``CONFIGURE_SCHEDULER`` shall be defined to a static definition of
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the scheduler data structures of the user scheduler.
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* ``CONFIGURE_SCHEDULER_TABLE_ENTRIES`` shall be defined to a scheduler
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table entry initializer for the user scheduler.
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* ``CONFIGURE_SCHEDULER_USER_PER_THREAD`` shall be defined to the type of
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the per-thread information of the user scheduler.
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At this time, the mechanics and requirements for writing a new scheduler
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are evolving and not fully documented. It is recommended that you look at
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the existing Deterministic Priority Scheduler in
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``cpukit/score/src/schedulerpriority*.c`` for guidance. For guidance on
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the configuration macros, please examine ``cpukit/sapi/include/confdefs.h``
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for how these are defined for the Deterministic Priority Scheduler.
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