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score: Multiprocessor Resource Sharing Protocol

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Add basic support for the Multiprocessor Resource Sharing Protocol
(MrsP).

The Multiprocessor Resource Sharing Protocol (MrsP) is defined in A.
Burns and A.J.  Wellings, A Schedulability Compatible Multiprocessor
Resource Sharing Protocol - MrsP, Proceedings of the 25th Euromicro
Conference on Real-Time Systems (ECRTS 2013), July 2013.  It is a
generalization of the Priority Ceiling Protocol to SMP systems.  Each
MrsP semaphore uses a ceiling priority per scheduler instance.  These
ceiling priorities can be specified with rtems_semaphore_set_priority().
A task obtaining or owning a MrsP semaphore will execute with the
ceiling priority for its scheduler instance as specified by the MrsP
semaphore object.  Tasks waiting to get ownership of a MrsP semaphore
will not relinquish the processor voluntarily.  In case the owner of a
MrsP semaphore gets preempted it can ask all tasks waiting for this
semaphore to help out and temporarily borrow the right to execute on one
of their assigned processors.

The help out feature is not implemented with this patch.
This commit is contained in:
Sebastian Huber
2014-05-21 10:33:43 +02:00
parent 9f058fb1c2
commit 8fcafdd553
32 changed files with 2251 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
doc/user/Makefile.am
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@@ -96,7 +96,7 @@ sem.texi: sem.t
-n "Barrier Manager" < $< > $@
barrier.texi: barrier.t
$(BMENU2) -p "Semaphore Manager SEMAPHORE_FLUSH - Unblock all tasks waiting on a semaphore" \
$(BMENU2) -p "Semaphore Manager SEMAPHORE_SET_PRIORITY - Set priority by scheduler for a semaphore" \
-u "Top" \
-n "Message Manager" < $< > $@

32
doc/user/conf.t
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@@ -685,6 +685,38 @@ API Semaphores that can be concurrently active.
@subheading NOTES:
This object class can be configured in unlimited allocation mode.
@c
@c === CONFIGURE_MAXIMUM_MRSP_SEMAPHORES ===
@c
@subsection Specify Maximum Classic API Semaphores usable with MrsP
@findex CONFIGURE_MAXIMUM_MRSP_SEMAPHORES
@table @b
@item CONSTANT:
@code{CONFIGURE_MAXIMUM_MRSP_SEMAPHORES}
@item DATA TYPE:
Unsigned integer (@code{uint32_t}).
@item RANGE:
Zero or positive.
@item DEFAULT VALUE:
The default value is 0.
@end table
@subheading DESCRIPTION:
@code{CONFIGURE_MAXIMUM_MRSP_SEMAPHORES} is the
maximum number of Classic API Semaphores using the Multiprocessor Resource
Sharing Protocol (MrsP) that can be concurrently active.
@subheading NOTES:
This configuration option is only used on SMP configurations. On uni-processor
configurations the Priority Ceiling Protocol is used for MrsP semaphores and
thus no extra memory is necessary.
@c
@c === CONFIGURE_MAXIMUM_MESSAGE_QUEUES ===
@c

213
doc/user/sem.t
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@@ -24,6 +24,8 @@ semaphore manager are:
@item @code{@value{DIRPREFIX}semaphore_obtain} - Acquire a semaphore
@item @code{@value{DIRPREFIX}semaphore_release} - Release a semaphore
@item @code{@value{DIRPREFIX}semaphore_flush} - Unblock all tasks waiting on a semaphore
@item @code{@value{DIRPREFIX}semaphore_set_priority} - Set priority by
scheduler for a semaphore
@end itemize
@section Background
@@ -173,6 +175,22 @@ any of the semaphores the task holds. Only when the task
releases ALL of the binary semaphores it holds will its priority
be restored to the normal value.
@subsection Multiprocessor Resource Sharing Protocol
The Multiprocessor Resource Sharing Protocol (MrsP) is defined in @cite{A.
Burns and A.J. Wellings, A Schedulability Compatible Multiprocessor Resource
Sharing Protocol - MrsP, Proceedings of the 25th Euromicro Conference on
Real-Time Systems (ECRTS 2013), July 2013}. It is a generalization of the
Priority Ceiling Protocol to SMP systems. Each MrsP semaphore uses a ceiling
priority per scheduler instance. These ceiling priorities can be specified
with @code{rtems_semaphore_set_priority()}. A task obtaining or owning a MrsP
semaphore will execute with the ceiling priority for its scheduler instance as
specified by the MrsP semaphore object. Tasks waiting to get ownership of a
MrsP semaphore will not relinquish the processor voluntarily. In case the
owner of a MrsP semaphore gets preempted it can ask all tasks waiting for this
semaphore to help out and temporarily borrow the right to execute on one of
their assigned processors.
@subsection Building a Semaphore Attribute Set
In general, an attribute set is built by a bitwise OR
@@ -198,11 +216,17 @@ inheritance (default)
@item @code{@value{RPREFIX}INHERIT_PRIORITY} - use priority inheritance
@item @code{@value{RPREFIX}PRIORITY_CEILING} - use priority ceiling
@item @code{@value{RPREFIX}NO_PRIORITY_CEILING} - do not use priority
ceiling (default)
@item @code{@value{RPREFIX}PRIORITY_CEILING} - use priority ceiling
@item @code{@value{RPREFIX}NO_MULTIPROCESSOR_RESOURCE_SHARING} - do not use
Multiprocessor Resource Sharing Protocol (default)
@item @code{@value{RPREFIX}MULTIPROCESSOR_RESOURCE_SHARING} - use
Multiprocessor Resource Sharing Protocol
@item @code{@value{RPREFIX}LOCAL} - local semaphore (default)
@item @code{@value{RPREFIX}GLOBAL} - global semaphore
@@ -489,11 +513,17 @@ inheritance (default)
@item @code{@value{RPREFIX}INHERIT_PRIORITY} - use priority inheritance
@item @code{@value{RPREFIX}PRIORITY_CEILING} - use priority ceiling
@item @code{@value{RPREFIX}NO_PRIORITY_CEILING} - do not use priority
ceiling (default)
@item @code{@value{RPREFIX}PRIORITY_CEILING} - use priority ceiling
@item @code{@value{RPREFIX}NO_MULTIPROCESSOR_RESOURCE_SHARING} - do not use
Multiprocessor Resource Sharing Protocol (default)
@item @code{@value{RPREFIX}MULTIPROCESSOR_RESOURCE_SHARING} - use
Multiprocessor Resource Sharing Protocol
@item @code{@value{RPREFIX}LOCAL} - local semaphore (default)
@item @code{@value{RPREFIX}GLOBAL} - global semaphore
@@ -512,6 +542,11 @@ earlier discussion on this.
The total number of global objects, including semaphores, is limited by
the maximum_global_objects field in the Configuration Table.
It is not allowed to create an initially locked MrsP semaphore and the
@code{@value{RPREFIX}INVALID_NUMBER} status code will be returned on SMP
configurations in this case. This prevents lock order reversal problems with
the allocator mutex.
@c
@c
@c
@@ -735,6 +770,10 @@ until the semaphore is released.
A clock tick is required to support the timeout functionality of
this directive.
It is not allowed to obtain a MrsP semaphore more than once by one task at a
time (nested access) and the @code{@value{RPREFIX}UNSATISFIED} status code will
be returned on SMP configurations in this case.
@c
@c
@c
@@ -831,6 +870,8 @@ procedure Semaphore_Flush (
@subheading DIRECTIVE STATUS CODES:
@code{@value{RPREFIX}SUCCESSFUL} - semaphore released successfully@*
@code{@value{RPREFIX}INVALID_ID} - invalid semaphore id@*
@code{@value{RPREFIX}NOT_DEFINED} - operation not defined for the protocol of
the semaphore@*
@code{@value{RPREFIX}ILLEGAL_ON_REMOTE_OBJECT} - not supported for remote semaphores
@subheading DESCRIPTION:
@@ -858,4 +899,168 @@ If the task to be unblocked resides on a different
node from the semaphore, then the waiting task is
unblocked, and the proxy used to represent the task is reclaimed.
It is not allowed to flush a MrsP semaphore and the
@code{@value{RPREFIX}NOT_DEFINED} status code will be returned on SMP
configurations in this case.
@c
@c
@c
@page
@subsection SEMAPHORE_SET_PRIORITY - Set priority by scheduler for a semaphore
@cindex set priority by scheduler for a semaphore
@subheading CALLING SEQUENCE:
@ifset is-C
@findex rtems_semaphore_set_priority
@example
rtems_status_code rtems_semaphore_set_priority(
rtems_id semaphore_id,
rtems_id scheduler_id,
rtems_task_priority new_priority,
rtems_task_priority *old_priority
);
@end example
@end ifset
@subheading DIRECTIVE STATUS CODES:
@code{@value{RPREFIX}SUCCESSFUL} - successful operation@*
@code{@value{RPREFIX}INVALID_ID} - invalid semaphore or scheduler id@*
@code{@value{RPREFIX}INVALID_ADDRESS} - @code{old_priority} is NULL@*
@code{@value{RPREFIX}INVALID_PRIORITY} - invalid new priority value@*
@code{@value{RPREFIX}NOT_DEFINED} - operation not defined for the protocol of
the semaphore@*
@code{@value{RPREFIX}ILLEGAL_ON_REMOTE_OBJECT} - not supported for remote semaphores
@subheading DESCRIPTION:
This directive sets the priority value with respect to the specified scheduler
of a semaphore.
The special priority value @code{RTEMS_CURRENT_PRIORITY} can be used to get the
current priority value without changing it.
The interpretation of the priority value depends on the protocol of the
semaphore object.
@itemize @bullet
@item The Multiprocessor Resource Sharing Protocol needs a ceiling priority per
scheduler instance. This operation can be used to specify these priority
values.
@item For the Priority Ceiling Protocol the ceiling priority is used with this
operation.
@item For other protocols this operation is not defined.
@end itemize
@subheading EXAMPLE:
@example
@group
#include <assert.h>
#include <stdlib.h>
#include <rtems.h>
#define SCHED_A rtems_build_name(' ', ' ', ' ', 'A')
#define SCHED_B rtems_build_name(' ', ' ', ' ', 'B')
static void Init(rtems_task_argument arg)
@{
rtems_status_code sc;
rtems_id semaphore_id;
rtems_id scheduler_a_id;
rtems_id scheduler_b_id;
rtems_task_priority prio;
/* Get the scheduler identifiers */
sc = rtems_scheduler_ident(SCHED_A, &scheduler_a_id);
assert(sc == RTEMS_SUCCESSFUL);
sc = rtems_scheduler_ident(SCHED_B, &scheduler_b_id);
assert(sc == RTEMS_SUCCESSFUL);
/* Create a MrsP semaphore object */
sc = rtems_semaphore_create(
rtems_build_name('M', 'R', 'S', 'P'),
1,
RTEMS_MULTIPROCESSOR_RESOURCE_SHARING
| RTEMS_BINARY_SEMAPHORE,
1,
&semaphore_id
);
assert(sc == RTEMS_SUCCESSFUL);
/*
* The ceiling priority values per scheduler are equal to the value specified
* for object creation.
*/
prio = RTEMS_CURRENT_PRIORITY;
sc = rtems_semaphore_set_priority(semaphore_id, scheduler_a_id, prio, &prio);
assert(sc == RTEMS_SUCCESSFUL);
assert(prio == 1);
/* Check the old value and set a new ceiling priority for scheduler B */
prio = 2;
sc = rtems_semaphore_set_priority(semaphore_id, scheduler_b_id, prio, &prio);
assert(sc == RTEMS_SUCCESSFUL);
assert(prio == 1);
/* Check the ceiling priority values */
prio = RTEMS_CURRENT_PRIORITY;
sc = rtems_semaphore_set_priority(semaphore_id, scheduler_a_id, prio, &prio);
assert(sc == RTEMS_SUCCESSFUL);
assert(prio == 1);
prio = RTEMS_CURRENT_PRIORITY;
sc = rtems_semaphore_set_priority(semaphore_id, scheduler_b_id, prio, &prio);
assert(sc == RTEMS_SUCCESSFUL);
assert(prio == 2);
sc = rtems_semaphore_delete(semaphore_id);
assert(sc == RTEMS_SUCCESSFUL);
exit(0);
@}
#define CONFIGURE_SMP_APPLICATION
#define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
#define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
#define CONFIGURE_MAXIMUM_TASKS 1
#define CONFIGURE_MAXIMUM_SEMAPHORES 1
#define CONFIGURE_MAXIMUM_MRSP_SEMAPHORES 1
#define CONFIGURE_SMP_MAXIMUM_PROCESSORS 2
#define CONFIGURE_SCHEDULER_SIMPLE_SMP
#include <rtems/scheduler.h>
RTEMS_SCHEDULER_CONTEXT_SIMPLE_SMP(a);
RTEMS_SCHEDULER_CONTEXT_SIMPLE_SMP(b);
#define CONFIGURE_SCHEDULER_CONTROLS \
RTEMS_SCHEDULER_CONTROL_SIMPLE_SMP(a, SCHED_A), \
RTEMS_SCHEDULER_CONTROL_SIMPLE_SMP(b, SCHED_B)
#define CONFIGURE_SMP_SCHEDULER_ASSIGNMENTS \
RTEMS_SCHEDULER_ASSIGN(0, RTEMS_SCHEDULER_ASSIGN_PROCESSOR_MANDATORY), \
RTEMS_SCHEDULER_ASSIGN(1, RTEMS_SCHEDULER_ASSIGN_PROCESSOR_MANDATORY)
#define CONFIGURE_RTEMS_INIT_TASKS_TABLE
#define CONFIGURE_INIT
#include <rtems/confdefs.h>
@end group
@end example