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c-user: Move some task directives

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Sebastian Huber 2017-02-01 13:07:25 +01:00
parent 3966353b33
commit a2389124d7
2 changed files with 234 additions and 237 deletions
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237
c-user/symmetric_multiprocessing_services.rst
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@ -48,14 +48,6 @@ The application level services currently provided are:
- rtems_scheduler_remove_processor_ - Remove processor from a scheduler - rtems_scheduler_remove_processor_ - Remove processor from a scheduler
- rtems_task_get_scheduler_ - Get scheduler of a task
- rtems_task_set_scheduler_ - Set scheduler of a task
- rtems_task_get_affinity_ - Get task processor affinity
- rtems_task_set_affinity_ - Set task processor affinity
Background Background
========== ==========
@ -583,37 +575,6 @@ the heir thread must be used during interrupt processing. For this purpose a
temporary per-processor stack is set up which may be used by the interrupt temporary per-processor stack is set up which may be used by the interrupt
prologue before the stack is switched to the interrupt stack. prologue before the stack is switched to the interrupt stack.
Operations
==========
Setting Affinity to a Single Processor
--------------------------------------
On some embedded applications targeting SMP systems, it may be beneficial to
lock individual tasks to specific processors. In this way, one can designate a
processor for I/O tasks, another for computation, etc.. The following
illustrates the code sequence necessary to assign a task an affinity for
processor with index ``processor_index``.
.. code-block:: c
#include <rtems.h>
#include <assert.h>
void pin_to_processor(rtems_id task_id, int processor_index)
{
rtems_status_code sc;
cpu_set_t cpuset;
CPU_ZERO(&cpuset);
CPU_SET(processor_index, &cpuset);
sc = rtems_task_set_affinity(task_id, sizeof(cpuset), &cpuset);
assert(sc == RTEMS_SUCCESSFUL);
}
It is important to note that the ``cpuset`` is not validated until the
``rtems_task_set_affinity`` call is made. At that point, it is validated
against the current system configuration.
Directives Directives
========== ==========
@ -840,201 +801,3 @@ NOTES:
Must be called from task context. This operation obtains and releases the Must be called from task context. This operation obtains and releases the
objects allocator lock. Removing a processor from a scheduler is a complex objects allocator lock. Removing a processor from a scheduler is a complex
operation that involves all tasks of the system. operation that involves all tasks of the system.
.. raw:: latex
\clearpage
.. _rtems_task_get_scheduler:
TASK_GET_SCHEDULER - Get scheduler of a task
--------------------------------------------
CALLING SEQUENCE:
.. code-block:: c
rtems_status_code rtems_task_get_scheduler(
rtems_id task_id,
rtems_id *scheduler_id
);
DIRECTIVE STATUS CODES:
.. list-table::
:class: rtems-table
* - ``RTEMS_SUCCESSFUL``
- successful operation
* - ``RTEMS_INVALID_ADDRESS``
- ``scheduler_id`` is NULL
* - ``RTEMS_INVALID_ID``
- invalid task id
DESCRIPTION:
Returns the scheduler identifier of a task identified by ``task_id`` in
``scheduler_id``.
NOTES:
None.
.. raw:: latex
\clearpage
.. _rtems_task_set_scheduler:
.. _TASK_SET_SCHEDULER - Set scheduler of a task:
TASK_SET_SCHEDULER - Set scheduler of a task
--------------------------------------------
CALLING SEQUENCE:
.. code-block:: c
rtems_status_code rtems_task_set_scheduler(
rtems_id task_id,
rtems_id scheduler_id
);
DIRECTIVE STATUS CODES:
.. list-table::
:class: rtems-table
* - ``RTEMS_SUCCESSFUL``
- successful operation
* - ``RTEMS_INVALID_ID``
- invalid task or scheduler id
* - ``RTEMS_INCORRECT_STATE``
- the task is in the wrong state to perform a scheduler change
DESCRIPTION:
Sets the scheduler of a task identified by ``task_id`` to the scheduler
identified by ``scheduler_id``. The scheduler of a task is initialized to
the scheduler of the task that created it.
NOTES:
None.
EXAMPLE:
.. code-block:: c
:linenos:
#include <rtems.h>
#include <assert.h>
void task(rtems_task_argument arg);
void example(void)
{
rtems_status_code sc;
rtems_id task_id;
rtems_id scheduler_id;
rtems_name scheduler_name;
scheduler_name = rtems_build_name('W', 'O', 'R', 'K');
sc = rtems_scheduler_ident(scheduler_name, &scheduler_id);
assert(sc == RTEMS_SUCCESSFUL);
sc = rtems_task_create(
rtems_build_name('T', 'A', 'S', 'K'),
1,
RTEMS_MINIMUM_STACK_SIZE,
RTEMS_DEFAULT_MODES,
RTEMS_DEFAULT_ATTRIBUTES,
&task_id
);
assert(sc == RTEMS_SUCCESSFUL);
sc = rtems_task_set_scheduler(task_id, scheduler_id);
assert(sc == RTEMS_SUCCESSFUL);
sc = rtems_task_start(task_id, task, 0);
assert(sc == RTEMS_SUCCESSFUL);
}
.. raw:: latex
\clearpage
.. _rtems_task_get_affinity:
TASK_GET_AFFINITY - Get task processor affinity
-----------------------------------------------
CALLING SEQUENCE:
.. code-block:: c
rtems_status_code rtems_task_get_affinity(
rtems_id id,
size_t cpusetsize,
cpu_set_t *cpuset
);
DIRECTIVE STATUS CODES:
.. list-table::
:class: rtems-table
* - ``RTEMS_SUCCESSFUL``
- successful operation
* - ``RTEMS_INVALID_ADDRESS``
- ``cpuset`` is NULL
* - ``RTEMS_INVALID_ID``
- invalid task id
* - ``RTEMS_INVALID_NUMBER``
- the affinity set buffer is too small for the current processor affinity
set of the task
DESCRIPTION:
Returns the current processor affinity set of the task in ``cpuset``. A
set bit in the affinity set means that the task can execute on this
processor and a cleared bit means the opposite.
NOTES:
None.
.. raw:: latex
\clearpage
.. _rtems_task_set_affinity:
TASK_SET_AFFINITY - Set task processor affinity
-----------------------------------------------
CALLING SEQUENCE:
.. code-block:: c
rtems_status_code rtems_task_set_affinity(
rtems_id id,
size_t cpusetsize,
const cpu_set_t *cpuset
);
DIRECTIVE STATUS CODES:
.. list-table::
:class: rtems-table
* - ``RTEMS_SUCCESSFUL``
- successful operation
* - ``RTEMS_INVALID_ADDRESS``
- ``cpuset`` is NULL
* - ``RTEMS_INVALID_ID``
- invalid task id
* - ``RTEMS_INVALID_NUMBER``
- invalid processor affinity set
DESCRIPTION:
Sets the processor affinity set for the task specified by ``cpuset``. A
set bit in the affinity set means that the task can execute on this
processor and a cleared bit means the opposite.
NOTES:
This function will not change the scheduler of the task. The intersection
of the processor affinity set and the set of processors owned by the
scheduler of the task must be non-empty. It is not an error if the
processor affinity set contains processors that are not part of the set of
processors owned by the scheduler instance of the task. A task will simply
not run under normal circumstances on these processors since the scheduler
ignores them. Some locking protocols may temporarily use processors that
are not included in the processor affinity set of the task. It is also not
an error if the processor affinity set contains processors that are not
part of the system.

234
c-user/task_manager.rst
View File

@ -43,6 +43,14 @@ and administer tasks. The directives provided by the task manager are:
- rtems_task_wake_when_ - Wake up when specified - rtems_task_wake_when_ - Wake up when specified
- rtems_task_get_scheduler_ - Get scheduler of a task
- rtems_task_set_scheduler_ - Set scheduler of a task
- rtems_task_get_affinity_ - Get task processor affinity
- rtems_task_set_affinity_ - Set task processor affinity
- rtems_task_iterate_ - Iterate Over Tasks - rtems_task_iterate_ - Iterate Over Tasks
Background Background
@ -511,6 +519,34 @@ delete itself by sending a "delete self" message, event, or signal, or by
restarting the task with special arguments which instruct the task to delete restarting the task with special arguments which instruct the task to delete
itself. itself.
Setting Affinity to a Single Processor
--------------------------------------
On some embedded applications targeting SMP systems, it may be beneficial to
lock individual tasks to specific processors. In this way, one can designate a
processor for I/O tasks, another for computation, etc.. The following
illustrates the code sequence necessary to assign a task an affinity for
processor with index ``processor_index``.
.. code-block:: c
#include <rtems.h>
#include <assert.h>
void pin_to_processor(rtems_id task_id, int processor_index)
{
rtems_status_code sc;
cpu_set_t cpuset;
CPU_ZERO(&cpuset);
CPU_SET(processor_index, &cpuset);
sc = rtems_task_set_affinity(task_id, sizeof(cpuset), &cpuset);
assert(sc == RTEMS_SUCCESSFUL);
}
It is important to note that the ``cpuset`` is not validated until the
``rtems_task_set_affinity`` call is made. At that point, it is validated
against the current system configuration.
Transition Advice for Obsolete Notepads Transition Advice for Obsolete Notepads
--------------------------------------- ---------------------------------------
@ -1354,6 +1390,204 @@ NOTES:
\clearpage \clearpage
.. _rtems_task_get_scheduler:
TASK_GET_SCHEDULER - Get scheduler of a task
--------------------------------------------
CALLING SEQUENCE:
.. code-block:: c
rtems_status_code rtems_task_get_scheduler(
rtems_id task_id,
rtems_id *scheduler_id
);
DIRECTIVE STATUS CODES:
.. list-table::
:class: rtems-table
* - ``RTEMS_SUCCESSFUL``
- successful operation
* - ``RTEMS_INVALID_ADDRESS``
- ``scheduler_id`` is NULL
* - ``RTEMS_INVALID_ID``
- invalid task id
DESCRIPTION:
Returns the scheduler identifier of a task identified by ``task_id`` in
``scheduler_id``.
NOTES:
None.
.. raw:: latex
\clearpage
.. _rtems_task_set_scheduler:
.. _TASK_SET_SCHEDULER - Set scheduler of a task:
TASK_SET_SCHEDULER - Set scheduler of a task
--------------------------------------------
CALLING SEQUENCE:
.. code-block:: c
rtems_status_code rtems_task_set_scheduler(
rtems_id task_id,
rtems_id scheduler_id
);
DIRECTIVE STATUS CODES:
.. list-table::
:class: rtems-table
* - ``RTEMS_SUCCESSFUL``
- successful operation
* - ``RTEMS_INVALID_ID``
- invalid task or scheduler id
* - ``RTEMS_INCORRECT_STATE``
- the task is in the wrong state to perform a scheduler change
DESCRIPTION:
Sets the scheduler of a task identified by ``task_id`` to the scheduler
identified by ``scheduler_id``. The scheduler of a task is initialized to
the scheduler of the task that created it.
NOTES:
None.
EXAMPLE:
.. code-block:: c
:linenos:
#include <rtems.h>
#include <assert.h>
void task(rtems_task_argument arg);
void example(void)
{
rtems_status_code sc;
rtems_id task_id;
rtems_id scheduler_id;
rtems_name scheduler_name;
scheduler_name = rtems_build_name('W', 'O', 'R', 'K');
sc = rtems_scheduler_ident(scheduler_name, &scheduler_id);
assert(sc == RTEMS_SUCCESSFUL);
sc = rtems_task_create(
rtems_build_name('T', 'A', 'S', 'K'),
1,
RTEMS_MINIMUM_STACK_SIZE,
RTEMS_DEFAULT_MODES,
RTEMS_DEFAULT_ATTRIBUTES,
&task_id
);
assert(sc == RTEMS_SUCCESSFUL);
sc = rtems_task_set_scheduler(task_id, scheduler_id);
assert(sc == RTEMS_SUCCESSFUL);
sc = rtems_task_start(task_id, task, 0);
assert(sc == RTEMS_SUCCESSFUL);
}
.. raw:: latex
\clearpage
.. _rtems_task_get_affinity:
TASK_GET_AFFINITY - Get task processor affinity
-----------------------------------------------
CALLING SEQUENCE:
.. code-block:: c
rtems_status_code rtems_task_get_affinity(
rtems_id id,
size_t cpusetsize,
cpu_set_t *cpuset
);
DIRECTIVE STATUS CODES:
.. list-table::
:class: rtems-table
* - ``RTEMS_SUCCESSFUL``
- successful operation
* - ``RTEMS_INVALID_ADDRESS``
- ``cpuset`` is NULL
* - ``RTEMS_INVALID_ID``
- invalid task id
* - ``RTEMS_INVALID_NUMBER``
- the affinity set buffer is too small for the current processor affinity
set of the task
DESCRIPTION:
Returns the current processor affinity set of the task in ``cpuset``. A
set bit in the affinity set means that the task can execute on this
processor and a cleared bit means the opposite.
NOTES:
None.
.. raw:: latex
\clearpage
.. _rtems_task_set_affinity:
TASK_SET_AFFINITY - Set task processor affinity
-----------------------------------------------
CALLING SEQUENCE:
.. code-block:: c
rtems_status_code rtems_task_set_affinity(
rtems_id id,
size_t cpusetsize,
const cpu_set_t *cpuset
);
DIRECTIVE STATUS CODES:
.. list-table::
:class: rtems-table
* - ``RTEMS_SUCCESSFUL``
- successful operation
* - ``RTEMS_INVALID_ADDRESS``
- ``cpuset`` is NULL
* - ``RTEMS_INVALID_ID``
- invalid task id
* - ``RTEMS_INVALID_NUMBER``
- invalid processor affinity set
DESCRIPTION:
Sets the processor affinity set for the task specified by ``cpuset``. A
set bit in the affinity set means that the task can execute on this
processor and a cleared bit means the opposite.
NOTES:
This function will not change the scheduler of the task. The intersection
of the processor affinity set and the set of processors owned by the
scheduler of the task must be non-empty. It is not an error if the
processor affinity set contains processors that are not part of the set of
processors owned by the scheduler instance of the task. A task will simply
not run under normal circumstances on these processors since the scheduler
ignores them. Some locking protocols may temporarily use processors that
are not included in the processor affinity set of the task. It is also not
an error if the processor affinity set contains processors that are not
part of the system.
.. raw:: latex
\clearpage
.. _rtems_task_iterate: .. _rtems_task_iterate:
TASK_ITERATE - Iterate Over Tasks TASK_ITERATE - Iterate Over Tasks