Maintain the priority of a thread for each scheduler instance via the
thread queue enqueue, extract, priority actions and surrender
operations. This replaces the primitive priority boosting.
Update #2556.
Add priority nodes which contribute to the overall thread priority.
The actual priority of a thread is now an aggregation of priority nodes.
The thread priority aggregation for the home scheduler instance of a
thread consists of at least one priority node, which is normally the
real priority of the thread. The locking protocols (e.g. priority
ceiling and priority inheritance), rate-monotonic period objects and the
POSIX sporadic server add, change and remove priority nodes.
A thread changes its priority now immediately, e.g. priority changes are
not deferred until the thread releases its last resource.
Replace the _Thread_Change_priority() function with
* _Thread_Priority_perform_actions(),
* _Thread_Priority_add(),
* _Thread_Priority_remove(),
* _Thread_Priority_change(), and
* _Thread_Priority_update().
Update #2412.
Update #2556.
There was a subtile race condition in _Thread_queue_Do_extract_locked().
It must first update the thread wait flags and then restore the default
thread wait state. In the previous implementation this could lead under
rare timing conditions to an ineffective _Thread_Wait_tranquilize()
resulting to a corrupt system state.
Update #2556.
The _Thread_Lock_acquire() function had a potentially infinite run-time
due to the lack of fairness at atomic operations level.
Update #2412.
Update #2556.
Update #2765.
Move the priority change due to priority interitance to the thread queue
enqueue operation to simplify the locking on SMP configurations.
Update #2412.
Update #2556.
Update #2765.
The thread priority is manifest in two independent areas. One area is
the user visible thread priority along with a potential thread queue.
The other is the scheduler. Currently, a thread priority update via
_Thread_Change_priority() first updates the user visble thread priority
and the thread queue, then the scheduler is notified if necessary. The
priority is passed to the scheduler via a local variable. A generation
counter ensures that the scheduler discards out-of-date priorities.
This use of a local variable ties the update in these two areas close
together. For later enhancements and the OMIP locking protocol
implementation we need more flexibility. Add a thread priority
information block to Scheduler_Node and synchronize priority value
updates via a sequence lock on SMP configurations.
Update #2556.
Move the writes to Thread_Control::current_priority and
Thread_Control::real_priority into _Thread_Change_priority() under the
protection of the thread lock. Add a filter function to
_Thread_Change_priority() to enable specialized variants.
Avoid race conditions during a thread priority restore with the new
Thread_Control::priority_restore_hint for an important average case
optimizations used by priority inheritance mutexes.
Update #2273.
Replace the Thread_Priority_control with more general
Thread_queue_Operations which will be used for generic priority change,
timeout, signal and wait queue operations in the future.
Update #2273.
Since the thread current priority change and thread queue requeue is
performed in one critical section it is possible to simplify the thread
queue requeue procedure. Add a thread queue agnostic thread priority
change handler so that we are able to use alternative thread queue
implementations.
Update #2273.
Atomically update the current priority of a thread and the wait queue.
Serialize the scheduler update in a separate critical section with a
generation number.
New test sptests/spintrcritical23.
Close#2310.
Previously, the _Thread_Heir was updated unconditionally in case a new
heir was determined. The _Thread_Dispatch_necessary was only updated in
case the executing thread was preemptible or an internal thread was
unblocked. Change this to update the _Thread_Heir and
_Thread_Dispatch_necessary only in case the currently selected heir
thread is preemptible or a dispatch is forced. Move the schedule
decision into the change priority operation and use the schedule
operation only in rtems_task_mode() in case preemption is enabled or an
ASR dispatch is necessary. This is a behaviour change. Previously, the
RTEMS_NO_PREEMPT also prevented signal delivery in certain cases (not
always). Now, signal delivery is no longer influenced by
RTEMS_NO_PREEMPT. Since the currently selected heir thread is used to
determine if a new heir is chosen, non-preemptible heir threads
currently not executing now prevent a new heir. This may have an
application impact, see change test tm04. Document this change in sp04.
Update #2273.
There was a lot of duplication between the discipline subroutines.
With the transition to RBTrees for priority discipline, there were
only a few lines of source code manipulating the data structure
for FIFO and priority. Thus is made sense to fold these back
into the main methods.
As part of doing this all of the tests for discipline were changed
to be in the same order.
Remove the scheduler parameter from most high level scheduler operations
like
- _Scheduler_Block(),
- _Scheduler_Unblock(),
- _Scheduler_Change_priority(),
- _Scheduler_Update_priority(),
- _Scheduler_Release_job(), and
- _Scheduler_Yield().
This simplifies the scheduler operations usage.
Rename _Scheduler_Update() to _Scheduler_Update_priority(). Add
parameter for the new thread priority to avoid direct usage of
Thread_Control::current_priority in the scheduler operation.
This function is only used by _Thread_Change_priority(). Make it static
to avoid the function call overhead in the performance critical function
_Thread_Change_priority().
The function to change a thread priority was too complex. Simplify it
with a new scheduler operation. This increases the average case
performance due to the simplified logic. The interrupt disabled
critical section is a bit prolonged since now the extract, update and
enqueue steps are executed atomically. This should however not impact
the worst-case interrupt latency since at least for the Deterministic
Priority Scheduler this sequence can be carried out with a wee bit of
instructions and no loops.
Add _Scheduler_Change_priority() to replace the sequence of
- _Thread_Set_transient(),
- _Scheduler_Extract(),
- _Scheduler_Enqueue(), and
- _Scheduler_Enqueue_first().
Delete STATES_TRANSIENT, _States_Is_transient() and
_Thread_Set_transient() since this state is now superfluous.
With this change it is possible to get rid of the
SCHEDULER_SMP_NODE_IN_THE_AIR state. This considerably simplifies the
implementation of the new SMP locking protocols.
Do not allocate the scheduler control structures from the workspace.
This is a preparation step for configuration of clustered/partitioned
schedulers on SMP.
Add call to _Scheduler_Schedule() in missing path after
_Thread_Set_transient() in _Thread_Change_priority(). See also
sptests/spintrcritical19.
Add thread parameter to _Scheduler_Schedule(). This parameter is
currently unused but may be used in future SMP schedulers.
Do heir selection in _Scheduler_Schedule(). Use
_Scheduler_Update_heir() for this in the particular scheduler
implementation.
Add and use _Scheduler_Generic_block().
Move implementation specific parts of tqdata.h, threadq.h and
threadq.inl into new header file threadqimpl.h. The threadq.h contains
now only the application visible API.
Delete tqdata.h.
Move implementation specific parts of thread.h and thread.inl into new
header file threadimpl.h. The thread.h contains now only the
application visible API.
Remove superfluous header file includes from various files.
Move implementation specific parts of scheduler.h and scheduler.inl into
new header file schedulerimpl.h. The scheduler.h contains now only the
application visible API.
Script does what is expected and tries to do it as
smartly as possible.
+ remove occurrences of two blank comment lines
next to each other after Id string line removed.
+ remove entire comment blocks which only exited to
contain CVS Ids
+ If the processing left a blank line at the top of
a file, it was removed.
* sapi/include/confdefs.h, score/Makefile.am,
score/include/rtems/score/scheduler.h,
score/include/rtems/score/schedulerpriority.h,
score/include/rtems/score/thread.h,
score/inline/rtems/score/scheduler.inl,
score/inline/rtems/score/schedulerpriority.inl,
score/src/scheduler.c, score/src/schedulerpriority.c,
score/src/schedulerpriorityblock.c,
score/src/schedulerpriorityschedule.c,
score/src/schedulerpriorityunblock.c,
score/src/schedulerpriorityyield.c, score/src/threadchangepriority.c,
score/src/threadclose.c, score/src/threadinitialize.c,
score/src/threadsetpriority.c, score/src/threadsettransient.c:
Significant clean up on Scheduler Plugin Interface. Names were
shortened. Missing operations added. Many scheduler files had
unneeded includes removed. Made pointer to scheduler information in
Thread_Control and Scheduler_Control a void * pointer because the
thread and scheduler wrapper should be unaware of scheduler types AND
this is broken for user provided schedulers.
* score/src/schedulerpriorityallocate.c,
score/src/schedulerpriorityenqueue.c,
score/src/schedulerpriorityenqueuefirst.c,
score/src/schedulerpriorityextract.c,
score/src/schedulerpriorityfree.c,
score/src/schedulerpriorityupdate.c: New files.
* score/src/schedulerprioritythreadschedulerallocate.c,
score/src/schedulerprioritythreadschedulerfree.c,
score/src/schedulerprioritythreadschedulerupdate.c: Removed.
* sapi/include/confdefs.h, sapi/include/rtems/config.h,
score/include/rtems/score/scheduler.h,
score/include/rtems/score/schedulerpriority.h,
score/inline/rtems/score/scheduler.inl,
score/inline/rtems/score/schedulerpriority.inl,
score/src/scheduler.c, score/src/schedulerpriority.c,
score/src/schedulerpriorityblock.c,
score/src/schedulerpriorityschedule.c,
score/src/schedulerprioritythreadschedulerallocate.c,
score/src/schedulerprioritythreadschedulerfree.c,
score/src/schedulerprioritythreadschedulerupdate.c,
score/src/schedulerpriorityunblock.c,
score/src/schedulerpriorityyield.c, score/src/threadchangepriority.c,
score/src/threadclearstate.c, score/src/threadclose.c,
score/src/threadinitialize.c, score/src/threadready.c,
score/src/threadresume.c, score/src/threadsetpriority.c,
score/src/threadsetstate.c, score/src/threadsuspend.c: Simplify the
pluggable scheduler interface. Its configuration made a table
of available schedulers and set a pointer to one of the.
This was heavy handed since you can only use one scheduler
in an application. This configuration mechanism resulted in a
scheduler pointer being passed around when you could put all
scheduler configuration in an initialized structure.
PR 1635/cpukit
* sapi/src/exinit.c, score/Makefile.am, score/preinstall.am,
score/include/rtems/score/bitfield.h,
score/include/rtems/score/priority.h,
score/include/rtems/score/thread.h,
score/inline/rtems/score/priority.inl,
score/inline/rtems/score/thread.inl,
score/src/threadchangepriority.c, score/src/threadclearstate.c,
score/src/threadready.c, score/src/threadresume.c,
score/src/threadsetpriority.c, score/src/threadsetstate.c,
score/src/threadsettransient.c, score/src/threadsuspend.c:
Refactoring of priority handling, to isolate the bitmap
implementation of priorities in the supercore so that priority
management is a little more modular. This change is in anticipation
of scheduler implementations that can select how they manage tracking
priority levels / finding the highest priority ready task. Note that
most of the changes here are simple renaming, to clarify the use of
the bitmap-based priority management.
* score/include/rtems/score/prioritybitmap.h,
score/inline/rtems/score/prioritybitmap.inl: New files.
* score/src/threadchangepriority.c: Just in case the transient
state was set when we entered, ensure that it is still set when
we exit.
* score/src/threadclose.c: When a thread is being deleted, it should
go into the dormant state -- not the transient state.
PR 1222/cpukit
* score/Makefile.am, score/include/rtems/score/coremutex.h,
score/include/rtems/score/threadq.h,
score/inline/rtems/score/coremutex.inl, score/src/coremsgsubmit.c,
score/src/coremutexsurrender.c, score/src/threadchangepriority.c,
score/src/threadclearstate.c, score/src/threadhandler.c,
score/src/threadinitialize.c, score/src/threadqdequeuefifo.c,
score/src/threadqdequeuepriority.c, score/src/threadqenqueue.c,
score/src/threadqenqueuefifo.c, score/src/threadqenqueuepriority.c,
score/src/threadqextractfifo.c, score/src/threadqextractpriority.c,
score/src/threadsetstate.c: Enhance so that when the prioirity of a
thread that is blocked on a priority based thread queue is changed,
that its placement in the queue is reevaluated based upon the new
priority. This enhancement includes modifications to the SuperCore as
well as new test cases.
* score/src/threadqrequeue.c: New file.
