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c-user: Simplify clustered scheduler configuration

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Close #3325.
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Sebastian Huber 2018-03-08 08:04:25 +01:00
parent 0472eada76
commit 154fb0f90a
1 changed files with 54 additions and 45 deletions
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c-user/configuring_a_system.rst
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@ -3614,11 +3614,11 @@ DESCRIPTION:
scheduling algorithm. If ``CONFIGURE_SCHEDULER_USER`` is defined then the
following additional macros must be defined:
- ``CONFIGURE_SCHEDULER_CONTEXT`` must be defined to a static definition of
the scheduler context of the user scheduler.
- ``CONFIGURE_SCHEDULER`` must be defined to a static definition of
the scheduler data structures of the user scheduler.
- ``CONFIGURE_SCHEDULER_CONTROLS`` must be defined to a scheduler control
initializer for the user scheduler.
- ``CONFIGURE_SCHEDULER_TABLE_ENTRIES`` must be defined to a scheduler
table entry initializer for the user scheduler.
- ``CONFIGURE_SCHEDULER_USER_PER_THREAD`` must be defined to the type of
the per-thread information of the user scheduler.
@ -3637,8 +3637,8 @@ Clustered Scheduler Configuration
=================================
Clustered scheduling helps to control the worst-case latencies in a
multi-processor system (SMP). The goal is to reduce the amount of shared state
in the system and thus prevention of lock contention. Modern multi-processor
multiprocessor system (SMP). The goal is to reduce the amount of shared state
in the system and thus prevention of lock contention. Modern multiprocessor
systems tend to have several layers of data and instruction caches. With
clustered scheduling it is possible to honour the cache topology of a system
and thus avoid expensive cache synchronization traffic.
@ -3646,7 +3646,7 @@ and thus avoid expensive cache synchronization traffic.
We have clustered scheduling in case the set of processors of a system is
partitioned into non-empty pairwise-disjoint subsets. These subsets are called
clusters. Clusters with a cardinality of one are partitions. Each cluster is
owned by exactly one scheduler instance.
owned by exactly one scheduler.
A clustered scheduler configuration is optional. By default, up to 32
processors are managed by the :ref:`EDF SMP Scheduler <SchedulerSMPEDF>`. In
@ -3674,51 +3674,60 @@ with the following defines
- :ref:`CONFIGURE_SCHEDULER_SIMPLE_SMP <CONFIGURE_SCHEDULER_SIMPLE_SMP>`.
This is necessary to calculate the per-thread overhead introduced by the
schedulers. After these definitions the configuration file must ``#include
<rtems/scheduler.h>`` to have access to scheduler-specific configuration
macros.
scheduler algorithms. After these definitions the configuration file must
``#include <rtems/scheduler.h>`` to have access to scheduler-specific
configuration macros.
It is possible to make more than one scheduler algorithm available to the
application. For example a :ref:`Simple Priority SMP Scheduler
<SchedulerSMPPrioritySimple>` could be used in a partition for low latency
tasks in addition to the :ref:`EDF SMP Scheduler <SchedulerSMPEDF>` for a
general-purpose cluster. Since the per-thread overhead depends on the
scheduler algorithm only the scheduler algorithms used by the application
should be configured.
Configuration Step 2 - Schedulers
---------------------------------
Each scheduler needs a context to store state information at run-time. Use the
following macros to create scheduler contexts
Each scheduler needs some data structures. Use the following macros to create
the scheduler data structures for a particular scheduler identified in the
configuration by ``name``.
- ``RTEMS_SCHEDULER_CONTEXT_EDF_SMP(name, max_cpu_count)``,
- ``RTEMS_SCHEDULER_EDF_SMP(name, max_cpu_count)``,
- ``RTEMS_SCHEDULER_CONTEXT_PRIORITY_AFFINITY_SMP(name, prio_count)``,
- ``RTEMS_SCHEDULER_PRIORITY_AFFINITY_SMP(name, prio_count)``,
- ``RTEMS_SCHEDULER_CONTEXT_PRIORITY_SMP(name, prio_count)``, and
- ``RTEMS_SCHEDULER_PRIORITY_SMP(name, prio_count)``, and
- ``RTEMS_SCHEDULER_CONTEXT_SIMPLE_SMP(name)``.
- ``RTEMS_SCHEDULER_SIMPLE_SMP(name)``.
The ``name`` parameter is used as part of a designator for a global variable,
so the usual C/C++ designator rules apply. This ``name`` is not the scheduler
object name. Additional parameters are scheduler-specific.
The ``name`` parameter is used as part of a designator for scheduler-specific
data structures, so the usual C/C++ designator rules apply. This ``name`` is
not the scheduler object name. Additional parameters are scheduler-specific.
.. _ConfigurationSchedulerTable:
Configuration Step 3 - Scheduler Table
--------------------------------------
The schedulers are registered in the system via the scheduler table.
To create the scheduler table define ``CONFIGURE_SCHEDULER_CONTROLS`` to a list
of the following scheduler control initializers
The schedulers are registered in the system via the scheduler table. To
populate the scheduler table define ``CONFIGURE_SCHEDULER_TABLE_ENTRIES`` to a
list of the following scheduler table entry initializers
- ``RTEMS_SCHEDULER_CONTROL_EDF_SMP(name, obj_name)``,
- ``RTEMS_SCHEDULER_TABLE_EDF_SMP(name, obj_name)``,
- ``RTEMS_SCHEDULER_CONTROL_PRIORITY_AFFINITY_SMP(name, obj_name)``,
- ``RTEMS_SCHEDULER_TABLE_PRIORITY_AFFINITY_SMP(name, obj_name)``,
- ``RTEMS_SCHEDULER_CONTROL_PRIORITY_SMP(name, obj_name)``, and
- ``RTEMS_SCHEDULER_TABLE_PRIORITY_SMP(name, obj_name)``, and
- ``RTEMS_SCHEDULER_CONTROL_SIMPLE_SMP(name, obj_name)``.
- ``RTEMS_SCHEDULER_TABLE_SIMPLE_SMP(name, obj_name)``.
The ``name`` parameter must correspond to the parameter defining the scheduler
context. The ``obj_name`` determines the scheduler object name and can be used
in :ref:`rtems_scheduler_ident() <rtems_scheduler_ident>` to get the scheduler
object identifier. The scheduler index is defined by the index of the
scheduler table. It is a configuration error to add a scheduler multiple times
to the scheduler table.
data structures of configuration step 2. The ``obj_name`` determines the
scheduler object name and can be used in :ref:`rtems_scheduler_ident()
<rtems_scheduler_ident>` to get the scheduler object identifier. The scheduler
index is defined by the index of the scheduler table. It is a configuration
error to add a scheduler multiple times to the scheduler table.
Configuration Step 4 - Processor to Scheduler Assignment
--------------------------------------------------------
@ -3731,17 +3740,17 @@ processor assignment to a scheduler can be optional or mandatory. The boot
processor must have a scheduler assigned. In case the system needs more
mandatory processors than available then a fatal run-time error will occur. To
specify the scheduler assignments define
``CONFIGURE_SMP_SCHEDULER_ASSIGNMENTS`` to a list of
``CONFIGURE_SCHEDULER_ASSIGNMENTS`` to a list of
- ``RTEMS_SCHEDULER_ASSIGN(scheduler_index, attr)`` and
- ``RTEMS_SCHEDULER_ASSIGN_NO_SCHEDULER``
macros. The ``scheduler_index`` parameter must
be a valid index into the scheduler table. The ``attr`` parameter defines the
scheduler assignment attributes. By default, a scheduler assignment to a
processor is optional. For the scheduler assignment attribute use one of the
mutually exclusive variants
macros. The ``scheduler_index`` parameter must be a valid index into the
scheduler table defined by configuration step 3. The ``attr`` parameter
defines the scheduler assignment attributes. By default, a scheduler
assignment to a processor is optional. For the scheduler assignment attribute
use one of the mutually exclusive variants
- ``RTEMS_SCHEDULER_ASSIGN_DEFAULT``,
@ -3786,22 +3795,22 @@ that the two systems cannot interfere in an undesirable way.
#include <rtems/scheduler.h>
/* Configuration Step 2 - Schedulers */
RTEMS_SCHEDULER_CONTEXT_PRIORITY_SMP(io, CONFIGURE_MAXIMUM_PRIORITY + 1);
RTEMS_SCHEDULER_CONTEXT_PRIORITY_SMP(work, CONFIGURE_MAXIMUM_PRIORITY + 1);
RTEMS_SCHEDULER_PRIORITY_SMP(io, CONFIGURE_MAXIMUM_PRIORITY + 1);
RTEMS_SCHEDULER_PRIORITY_SMP(work, CONFIGURE_MAXIMUM_PRIORITY + 1);
/* Configuration Step 3 - Scheduler Table */
#define CONFIGURE_SCHEDULER_CONTROLS \\
RTEMS_SCHEDULER_CONTROL_PRIORITY_SMP( \
#define CONFIGURE_SCHEDULER_TABLE_ENTRIES \\
RTEMS_SCHEDULER_TABLE_PRIORITY_SMP( \
io, \
rtems_build_name('I', 'O', ' ', ' ') \
), \
RTEMS_SCHEDULER_CONTROL_PRIORITY_SMP( \
RTEMS_SCHEDULER_TABLE_PRIORITY_SMP( \
work, \
rtems_build_name('W', 'O', 'R', 'K') \
)
/* Configuration Step 4 - Processor to Scheduler Assignment */
#define CONFIGURE_SMP_SCHEDULER_ASSIGNMENTS \
#define CONFIGURE_SCHEDULER_ASSIGNMENTS \
RTEMS_SCHEDULER_ASSIGN(0, RTEMS_SCHEDULER_ASSIGN_PROCESSOR_MANDATORY), \
RTEMS_SCHEDULER_ASSIGN_NO_SCHEDULER, \
RTEMS_SCHEDULER_ASSIGN(1, RTEMS_SCHEDULER_ASSIGN_PROCESSOR_MANDATORY), \
@ -3814,7 +3823,7 @@ that the two systems cannot interfere in an undesirable way.
Configuration Errors
--------------------
In case one of the scheduler indices in ``CONFIGURE_SMP_SCHEDULER_ASSIGNMENTS``
In case one of the scheduler indices in ``CONFIGURE_SCHEDULER_ASSIGNMENTS``
is invalid a link-time error will occur with an undefined reference to
``RTEMS_SCHEDULER_INVALID_INDEX``.
@ -3832,7 +3841,7 @@ or a lack of processors on the system. The fatal source is
- ``SMP_FATAL_START_OF_MANDATORY_PROCESSOR_FAILED`` - the start of a mandatory
processor failed during system initialization. The system may not have this
processor at all or it could be a problem with a boot loader for example.
Check the ``CONFIGURE_SMP_SCHEDULER_ASSIGNMENTS`` definition.
Check the ``CONFIGURE_SCHEDULER_ASSIGNMENTS`` definition.
- ``SMP_FATAL_MULTITASKING_START_ON_UNASSIGNED_PROCESSOR`` - it is not allowed
to start multitasking on a processor with no scheduler assigned.