[rtems commit] score: Add _Scheduler_Help()
Sebastian Huber
sebh at rtems.org
Tue Jul 8 14:57:17 UTC 2014
Module: rtems
Branch: master
Commit: ac532f33508cc052108a8f8d9ab1eb933bb5a6f8
Changeset: http://git.rtems.org/rtems/commit/?id=ac532f33508cc052108a8f8d9ab1eb933bb5a6f8
Author: Sebastian Huber <sebastian.huber at embedded-brains.de>
Date: Fri Jul 4 13:40:10 2014 +0200
score: Add _Scheduler_Help()
Manage the help state of threads with respect to scheduling decisions.
---
cpukit/score/include/rtems/score/mrspimpl.h | 32 ++++---
cpukit/score/include/rtems/score/scheduler.h | 96 ++++++++++++++++++++
cpukit/score/include/rtems/score/schedulerimpl.h | 41 +++++++++
.../score/include/rtems/score/schedulersmpimpl.h | 4 +-
4 files changed, 159 insertions(+), 14 deletions(-)
diff --git a/cpukit/score/include/rtems/score/mrspimpl.h b/cpukit/score/include/rtems/score/mrspimpl.h
index 5efb619..6aa45a8 100644
--- a/cpukit/score/include/rtems/score/mrspimpl.h
+++ b/cpukit/score/include/rtems/score/mrspimpl.h
@@ -102,6 +102,7 @@ RTEMS_INLINE_ROUTINE void _MRSP_Claim_ownership(
_Resource_Set_owner( &mrsp->Resource, &new_owner->Resource_node );
mrsp->initial_priority_of_owner = initial_priority;
_MRSP_Elevate_priority( mrsp, new_owner, ceiling_priority );
+ _Scheduler_Thread_change_help_state( new_owner, SCHEDULER_HELP_ACTIVE_OWNER );
}
RTEMS_INLINE_ROUTINE MRSP_Status _MRSP_Initialize(
@@ -185,6 +186,7 @@ RTEMS_INLINE_ROUTINE MRSP_Status _MRSP_Wait_for_ownership(
MRSP_Rival rival;
bool previous_life_protection;
unsigned int state;
+ Scheduler_Help_state previous_help_state;
_MRSP_Elevate_priority( mrsp, executing, ceiling_priority );
@@ -193,6 +195,8 @@ RTEMS_INLINE_ROUTINE MRSP_Status _MRSP_Wait_for_ownership(
_Chain_Append_unprotected( &mrsp->Rivals, &rival.Node );
_Resource_Add_rival( &mrsp->Resource, &executing->Resource_node );
_Resource_Node_set_dependency( &executing->Resource_node, &mrsp->Resource );
+ previous_help_state =
+ _Scheduler_Thread_change_help_state( executing, SCHEDULER_HELP_ACTIVE_RIVAL );
_MRSP_Set_root(
&executing->Resource_node,
_Resource_Node_get_root( owner )
@@ -234,11 +238,10 @@ RTEMS_INLINE_ROUTINE MRSP_Status _MRSP_Wait_for_ownership(
mrsp->initial_priority_of_owner = initial_priority;
status = MRSP_SUCCESSFUL;
} else {
- Resource_Node *executing_node = &executing->Resource_node;
-
- _Resource_Node_extract( executing_node );
- _Resource_Node_set_dependency( executing_node, NULL );
- _MRSP_Set_root( executing_node, executing_node );
+ _Resource_Node_extract( &executing->Resource_node );
+ _Resource_Node_set_dependency( &executing->Resource_node, NULL );
+ _Scheduler_Thread_change_help_state( executing, previous_help_state );
+ _MRSP_Set_root( &executing->Resource_node, &executing->Resource_node );
_MRSP_Restore_priority( mrsp, executing, initial_priority );
status = MRSP_TIMEOUT;
@@ -324,16 +327,21 @@ RTEMS_INLINE_ROUTINE MRSP_Status _MRSP_Release(
_Resource_Set_owner( &mrsp->Resource, NULL );
} else {
MRSP_Rival *rival = (MRSP_Rival *) _Chain_First( &mrsp->Rivals );
- Resource_Node *new_owner = &rival->thread->Resource_node;
-
- _Resource_Node_extract( new_owner );
- _Resource_Node_set_dependency( new_owner, NULL );
- _Resource_Node_add_resource( new_owner, &mrsp->Resource );
- _Resource_Set_owner( &mrsp->Resource, new_owner );
- _MRSP_Set_root( new_owner, new_owner );
+ Thread_Control *new_owner = rival->thread;
+
+ _Resource_Node_extract( &new_owner->Resource_node );
+ _Resource_Node_set_dependency( &new_owner->Resource_node, NULL );
+ _Resource_Node_add_resource( &new_owner->Resource_node, &mrsp->Resource );
+ _Resource_Set_owner( &mrsp->Resource, &new_owner->Resource_node );
+ _Scheduler_Thread_change_help_state( new_owner, SCHEDULER_HELP_ACTIVE_OWNER );
+ _MRSP_Set_root( &new_owner->Resource_node, &new_owner->Resource_node );
_MRSP_Add_state( rival, MRSP_RIVAL_STATE_NEW_OWNER );
}
+ if ( !_Resource_Node_owns_resources( &executing->Resource_node ) ) {
+ _Scheduler_Thread_change_help_state( executing, SCHEDULER_HELP_YOURSELF );
+ }
+
return MRSP_SUCCESSFUL;
}
diff --git a/cpukit/score/include/rtems/score/scheduler.h b/cpukit/score/include/rtems/score/scheduler.h
index 831accb..bb30a8e 100644
--- a/cpukit/score/include/rtems/score/scheduler.h
+++ b/cpukit/score/include/rtems/score/scheduler.h
@@ -161,6 +161,75 @@ struct Scheduler_Control {
uint32_t name;
};
+#if defined(RTEMS_SMP)
+/**
+ * @brief State to indicate potential help for other threads.
+ *
+ * @dot
+ * digraph state {
+ * y [label="HELP YOURSELF"];
+ * ao [label="HELP ACTIVE OWNER"];
+ * ar [label="HELP ACTIVE RIVAL"];
+ *
+ * y -> ao [label="obtain"];
+ * y -> ar [label="wait for obtain"];
+ * ao -> y [label="last release"];
+ * ao -> r [label="wait for obtain"];
+ * ar -> r [label="timeout"];
+ * ar -> ao [label="timeout"];
+ * }
+ * @enddot
+ */
+typedef enum {
+ /**
+ * @brief This scheduler node is solely used by the owner thread.
+ *
+ * This thread owns no resources using a helping protocol and thus does not
+ * take part in the scheduler helping protocol. No help will be provided for
+ * other thread.
+ */
+ SCHEDULER_HELP_YOURSELF,
+
+ /**
+ * @brief This scheduler node is owned by a thread actively owning a resource.
+ *
+ * This scheduler node can be used to help out threads.
+ *
+ * In case this scheduler node changes its state from ready to scheduled and
+ * the thread executes using another node, then an idle thread will be
+ * provided as a user of this node to temporarily execute on behalf of the
+ * owner thread. Thus lower priority threads are denied access to the
+ * processors of this scheduler instance.
+ *
+ * In case a thread actively owning a resource performs a blocking operation,
+ * then an idle thread will be used also in case this node is in the
+ * scheduled state.
+ */
+ SCHEDULER_HELP_ACTIVE_OWNER,
+
+ /**
+ * @brief This scheduler node is owned by a thread actively obtaining a
+ * resource currently owned by another thread.
+ *
+ * This scheduler node can be used to help out threads.
+ *
+ * The thread owning this node is ready and will give away its processor in
+ * case the thread owning the resource asks for help.
+ */
+ SCHEDULER_HELP_ACTIVE_RIVAL,
+
+ /**
+ * @brief This scheduler node is owned by a thread obtaining a
+ * resource currently owned by another thread.
+ *
+ * This scheduler node can be used to help out threads.
+ *
+ * The thread owning this node is blocked.
+ */
+ SCHEDULER_HELP_PASSIVE
+} Scheduler_Help_state;
+#endif
+
/**
* @brief Scheduler node for per-thread data.
*/
@@ -179,9 +248,36 @@ struct Scheduler_Node {
Chain_Node Node;
/**
+ * @brief The thread using this node.
+ */
+ Thread_Control *user;
+
+ /**
+ * @brief The help state of this node.
+ */
+ Scheduler_Help_state help_state;
+
+ /**
* @brief The thread owning this node.
*/
Thread_Control *owner;
+
+ /**
+ * @brief The idle thread claimed by this node in case the help state is
+ * SCHEDULER_HELP_ACTIVE_OWNER.
+ *
+ * Active owners will lend their own node to an idle thread in case they
+ * execute currently using another node or in case they perform a blocking
+ * operation. This is necessary to ensure the priority ceiling protocols
+ * work across scheduler boundaries.
+ */
+ Thread_Control *idle;
+
+ /**
+ * @brief The thread accepting help by this node in case the help state is
+ * not SCHEDULER_HELP_YOURSELF.
+ */
+ Thread_Control *accepts_help;
#endif
};
diff --git a/cpukit/score/include/rtems/score/schedulerimpl.h b/cpukit/score/include/rtems/score/schedulerimpl.h
index 1a8b6b0..edb68b6 100644
--- a/cpukit/score/include/rtems/score/schedulerimpl.h
+++ b/cpukit/score/include/rtems/score/schedulerimpl.h
@@ -77,6 +77,15 @@ RTEMS_INLINE_ROUTINE const Scheduler_Control *_Scheduler_Get_by_CPU(
return _Scheduler_Get_by_CPU_index( cpu_index );
}
+#if defined(RTEMS_SMP)
+RTEMS_INLINE_ROUTINE Thread_Control *_Scheduler_Node_get_user(
+ const Scheduler_Node *node
+)
+{
+ return node->user;
+}
+#endif
+
/**
* The preferred method to add a new scheduler is to define the jump table
* entries and add a case to the _Scheduler_Initialize routine.
@@ -658,7 +667,11 @@ RTEMS_INLINE_ROUTINE void _Scheduler_Node_do_initialize(
)
{
#if defined(RTEMS_SMP)
+ node->user = the_thread;
+ node->help_state = SCHEDULER_HELP_YOURSELF;
node->owner = the_thread;
+ node->idle = NULL;
+ node->accepts_help = the_thread;
#else
(void) node;
(void) the_thread;
@@ -672,6 +685,34 @@ RTEMS_INLINE_ROUTINE Thread_Control *_Scheduler_Node_get_owner(
{
return node->owner;
}
+
+RTEMS_INLINE_ROUTINE Thread_Control *_Scheduler_Node_get_idle(
+ const Scheduler_Node *node
+)
+{
+ return node->idle;
+}
+
+/**
+ * @brief Changes the scheduler help state of a thread.
+ *
+ * @param[in] the_thread The thread.
+ * @param[in] new_help_state The new help state.
+ *
+ * @return The previous help state.
+ */
+RTEMS_INLINE_ROUTINE Scheduler_Help_state _Scheduler_Thread_change_help_state(
+ Thread_Control *the_thread,
+ Scheduler_Help_state new_help_state
+)
+{
+ Scheduler_Node *node = _Scheduler_Thread_get_node( the_thread );
+ Scheduler_Help_state previous_help_state = node->help_state;
+
+ node->help_state = new_help_state;
+
+ return previous_help_state;
+}
#endif
/** @} */
diff --git a/cpukit/score/include/rtems/score/schedulersmpimpl.h b/cpukit/score/include/rtems/score/schedulersmpimpl.h
index 3ec499b..b7d86a3 100644
--- a/cpukit/score/include/rtems/score/schedulersmpimpl.h
+++ b/cpukit/score/include/rtems/score/schedulersmpimpl.h
@@ -455,8 +455,8 @@ static inline void _Scheduler_SMP_Allocate_processor(
Scheduler_SMP_Allocate_processor allocate_processor
)
{
- Thread_Control *scheduled_thread = _Scheduler_Node_get_owner( scheduled );
- Thread_Control *victim_thread = _Scheduler_Node_get_owner( victim );
+ Thread_Control *scheduled_thread = _Scheduler_Node_get_user( scheduled );
+ Thread_Control *victim_thread = _Scheduler_Node_get_user( victim );
_Scheduler_SMP_Node_change_state(
_Scheduler_SMP_Node_downcast( scheduled ),
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