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Sebastian Huber
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bf78123ada
@ -3326,17 +3326,13 @@ DEFAULT VALUE:
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This is not defined by default.
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DESCRIPTION:
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The Constant Bandwidth Server Scheduler (CBS) is an alternative scheduler
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in RTEMS for uniprocessor applications. The CBS is a budget aware
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extension of EDF scheduler. The goal of this scheduler is to ensure
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temporal isolation of tasks. The CBS is equipped with a set of additional
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rules and provides with an extensive API.
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This scheduler may be explicitly selected by defining
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``CONFIGURE_SCHEDULER_CBS``.
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If defined, then the :ref:`Constant Bandwidth Server (CBS) Scheduler
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<SchedulerCBS>` algorithm is made available to the application.
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NOTES:
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None.
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In case no explicit :ref:`clustered scheduler configuration
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<ConfigurationSchedulersClustered>` is present, then it is used as the
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scheduler for exactly one processor.
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.. index:: CONFIGURE_SCHEDULER_EDF
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@ -3358,21 +3354,13 @@ DEFAULT VALUE:
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This is not defined by default.
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DESCRIPTION:
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The Earliest Deadline First Scheduler (EDF) is an alternative scheduler in
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RTEMS for uniprocessor applications. The EDF schedules tasks with dynamic
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priorities equal to deadlines. The deadlines are declared using only Rate
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Monotonic manager which handles periodic behavior. Period is always equal
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to deadline. If a task does not have any deadline declared or the deadline
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is cancelled, the task is considered a background task which is scheduled
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in case no deadline-driven tasks are ready to run. Moreover, multiple
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background tasks are scheduled according their priority assigned upon
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initialization. All ready tasks reside in a single ready queue.
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This scheduler may be explicitly selected by defining
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``CONFIGURE_SCHEDULER_EDF``.
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If defined, then the :ref:`Earliest Deadline First (EDF) Scheduler
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<SchedulerEDF>` algorithm is made available to the application.
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NOTES:
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None.
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In case no explicit :ref:`clustered scheduler configuration
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<ConfigurationSchedulersClustered>` is present, then it is used as the
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scheduler for exactly one processor.
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.. index:: CONFIGURE_SCHEDULER_EDF_SMP
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@ -3394,11 +3382,20 @@ DEFAULT VALUE:
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This is not defined by default.
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DESCRIPTION:
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If defined, then the Earliest Deadline First (EDF) SMP Scheduler is
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selected as the default scheduler.
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If defined, then the :ref:`Earliest Deadline First (EDF) SMP Scheduler
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<SchedulerSMPEDF>` algorithm is made available to the application.
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NOTES:
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None.
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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:`clustered scheduler configuration
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<ConfigurationSchedulersClustered>` is present, then it is used as the
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scheduler for up to 32 processors.
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This scheduler algorithm is the default in SMP configurations and is only
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selected when :ref:`CONFIGURE_MAXIMUM_PROCESSORS
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<CONFIGURE_MAXIMUM_PROCESSORS>` is greater than one.
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.. index:: CONFIGURE_SCHEDULER_NAME
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@ -3456,16 +3453,49 @@ DEFAULT VALUE:
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this configuration parameter is redundant.
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DESCRIPTION:
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The Deterministic Priority Scheduler is the default scheduler in RTEMS for
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uniprocessor applications and is designed for predictable performance
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under the highest loads. It can block or unblock a thread in a constant
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amount of time. This scheduler requires a variable amount of memory based
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upon the number of priorities configured in the system.
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If defined, then the :ref:`Deterministic Priority Scheduler
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<SchedulerPriority>` algorithm is made available to the application.
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NOTES:
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This scheduler may be explicitly selected by defining
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``CONFIGURE_SCHEDULER_PRIORITY`` although this is equivalent to the default
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behavior.
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In case no explicit :ref:`clustered scheduler configuration
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<ConfigurationSchedulersClustered>` is present, then it is used as the
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scheduler for exactly one processor.
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This scheduler algorithm is the default when
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:ref:`CONFIGURE_MAXIMUM_PROCESSORS <CONFIGURE_MAXIMUM_PROCESSORS>` is
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exactly one.
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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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DATA TYPE:
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Boolean feature macro.
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RANGE:
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Defined or undefined.
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DEFAULT VALUE:
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This is not defined by default.
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DESCRIPTION:
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If defined, then the :ref:`Arbitrary Processor Affinity SMP Scheduler
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<SchedulerSMPPriorityAffinity>` algorithm is made available to the
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application.
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NOTES:
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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:`clustered scheduler configuration
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<ConfigurationSchedulersClustered>` is present, then it is used as the
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scheduler for up to 32 processors.
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.. index:: CONFIGURE_SCHEDULER_PRIORITY_SMP
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@ -3487,19 +3517,16 @@ DEFAULT VALUE:
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This is not defined by default.
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DESCRIPTION:
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The Deterministic Priority SMP Scheduler is derived from the Deterministic
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Priority Scheduler but is capable of scheduling threads across multiple
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processors.
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In a configuration with SMP enabled at configure time, it may be explicitly
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selected by defining ``CONFIGURE_SCHEDULER_PRIORITY_SMP``.
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If defined, then the :ref:`Deterministic Priority SMP Scheduler
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<SchedulerSMPPriority>` algorithm is made available to the application.
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NOTES:
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This scheduler is only available when RTEMS is configured with SMP support
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enabled.
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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 is currently the default in SMP configurations and is only
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selected when ``CONFIGURE_MAXIMUM_PROCESSORS`` is greater than one.
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In case no explicit :ref:`clustered scheduler configuration
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<ConfigurationSchedulersClustered>` is present, then it is used as the
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scheduler for up to 32 processors.
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.. index:: CONFIGURE_SCHEDULER_SIMPLE
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@ -3521,19 +3548,13 @@ DEFAULT VALUE:
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This is not defined by default.
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DESCRIPTION:
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When defined, the Simple Priority Scheduler is used at the thread
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scheduling algorithm. This is an alternative scheduler in RTEMS. It is
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designed to provide the same task scheduling behaviour as the Deterministic
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Priority Scheduler while being simpler in implementation and uses less
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memory for data management. It maintains a single sorted list of all ready
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threads. Thus blocking or unblocking a thread is not a constant time
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operation with this scheduler.
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This scheduler may be explicitly selected by defining
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``CONFIGURE_SCHEDULER_SIMPLE``.
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If defined, then the :ref:`Simple Priority Scheduler
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<SchedulerPrioritySimple>` algorithm is made available to the application.
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NOTES:
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This scheduler is appropriate for use in small systems where RAM is limited.
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In case no explicit :ref:`clustered scheduler configuration
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<ConfigurationSchedulersClustered>` is present, then it is used as the
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scheduler for exactly one processor.
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.. index:: CONFIGURE_SCHEDULER_SIMPLE_SMP
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@ -3555,25 +3576,17 @@ DEFAULT VALUE:
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This is not defined by default.
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DESCRIPTION:
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The Simple SMP Priority Scheduler is derived from the Simple Priority
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Scheduler but is capable of scheduling threads across multiple processors.
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It is designed to provide the same task scheduling behaviour as the
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Deterministic Priority Scheduler while distributing threads across multiple
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processors. Being based upon the Simple Priority Scheduler, it also
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maintains a single sorted list of all ready threads. Thus blocking or
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unblocking a thread is not a constant time operation with this scheduler.
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In addition, when allocating threads to processors, the algorithm is not
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constant time. This algorithm was not designed with efficiency as a primary
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design goal. Its primary design goal was to provide an SMP-aware
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scheduling algorithm that is simple to understand.
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In a configuration with SMP enabled at configure time, it may be explicitly
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selected by defining ``CONFIGURE_SCHEDULER_SIMPLE_SMP``.
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If defined, then the :ref:`Simple Priority SMP Scheduler
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<SchedulerSMPPrioritySimple>` algorithm is made available to the
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application.
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NOTES:
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This scheduler is only available when RTEMS is configured with SMP support
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enabled.
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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:`clustered scheduler configuration
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<ConfigurationSchedulersClustered>` is present, then it is used as the
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scheduler for up to 32 processors.
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.. index:: CONFIGURE_SCHEDULER_USER
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@ -3635,9 +3648,10 @@ partitioned into non-empty pairwise-disjoint subsets. These subsets are called
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clusters. Clusters with a cardinality of one are partitions. Each cluster is
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owned by exactly one scheduler instance.
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A clustered scheduler configuration is optional. By default, all processors are
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managed by the :ref:`EDF SMP Scheduler <SchedulerSMPEDF>`. In order to use
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clustered scheduling the application designer has to answer two questions.
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A clustered scheduler configuration is optional. By default, up to 32
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processors are managed by the :ref:`EDF SMP Scheduler <SchedulerSMPEDF>`. In
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order to use clustered scheduling the application designer has to answer two
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questions.
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#. How is the set of processors partitioned into clusters?
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@ -3651,13 +3665,13 @@ Configuration Step 1 - Scheduler Algorithms
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Firstly, the application must select which scheduling algorithms are available
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with the following defines
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- ``CONFIGURE_SCHEDULER_EDF_SMP``,
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- :ref:`CONFIGURE_SCHEDULER_EDF_SMP <CONFIGURE_SCHEDULER_EDF_SMP>`,
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- ``CONFIGURE_SCHEDULER_PRIORITY_AFFINITY_SMP``,
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- :ref:`CONFIGURE_SCHEDULER_PRIORITY_AFFINITY_SMP <CONFIGURE_SCHEDULER_PRIORITY_AFFINITY_SMP>`,
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- ``CONFIGURE_SCHEDULER_PRIORITY_SMP``, and
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- :ref:`CONFIGURE_SCHEDULER_PRIORITY_SMP <CONFIGURE_SCHEDULER_PRIORITY_SMP>`, and
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- ``CONFIGURE_SCHEDULER_SIMPLE_SMP``.
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- :ref:`CONFIGURE_SCHEDULER_SIMPLE_SMP <CONFIGURE_SCHEDULER_SIMPLE_SMP>`.
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This is necessary to calculate the per-thread overhead introduced by the
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schedulers. After these definitions the configuration file must ``#include
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