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* score: Optimize scheduler priority updatesSebastian Huber2017-11-201-9/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Thread priority changes may append or prepend the thread to its priority group on the scheduler ready queue. Previously, a separate priority value and a prepend-it flag in the scheduler node were used to propagate a priority change to the scheduler. Now, use an append-it bit in the priority control and reduce the plain priority value to 63 bits. This change leads to a significant code size reduction (about 25%) of the SMP schedulers. The negligible increase of the standard priority scheduler is due to some additional shift operations (SCHEDULER_PRIORITY_MAP() and SCHEDULER_PRIORITY_UNMAP()). Before: text filename 136 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleblock.o 464 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimplechangepriority.o 24 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimple.o 108 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleschedule.o 292 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleunblock.o 264 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleyield.o text filename 280 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityblock.o 488 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerprioritychangepriority.o 200 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriority.o 164 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityschedule.o 328 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityunblock.o 200 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityyield.o text filename 24112 arm-rtems5/c/imx7/cpukit/score/src/libscore_a-scheduleredfsmp.o text filename 37204 sparc-rtems5/c/gr740/cpukit/score/src/libscore_a-scheduleredfsmp.o text filename 42236 powerpc-rtems5/c/qoriq_e6500_32/cpukit/score/src/libscore_a-scheduleredfsmp.o After: text filename 136 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleblock.o 272 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimplechangepriority.o 24 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimple.o 108 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleschedule.o 292 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleunblock.o 264 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulersimpleyield.o text filename 280 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityblock.o 488 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerprioritychangepriority.o 208 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriority.o 164 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityschedule.o 332 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityunblock.o 200 sparc-rtems5/c/erc32/cpukit/score/src/libscore_a-schedulerpriorityyield.o text filename 18860 arm-rtems5/c/imx7/cpukit/score/src/libscore_a-scheduleredfsmp.o text filename 28520 sparc-rtems5/c/gr740/cpukit/score/src/libscore_a-scheduleredfsmp.o text filename 32664 powerpc-rtems5/c/qoriq_e6500_32/cpukit/score/src/libscore_a-scheduleredfsmp.o
* score: Simplify update priority scheduler opSebastian Huber2016-11-021-4/+2
| | | | Remove unused return status.
* score: Pass scheduler node to block operationSebastian Huber2016-11-021-1/+1
| | | | | | Changed for consistency with other scheduler operations. Update #2556.
* score: Pass scheduler node to update priority opSebastian Huber2016-11-021-3/+2
| | | | | | | This enables to call this scheduler operation for all scheduler nodes available to a thread. Update #2556.
* score: Add thread priority to scheduler nodesSebastian Huber2016-06-221-6/+14
| | | | | | | | | | | | | | | | | | 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.
* score: Update _Thread_Heir only if necessarySebastian Huber2015-03-051-0/+2
| | | | | | | | | | | | | | | | | | | | 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.
* score: Need for help indicator for scheduler opsSebastian Huber2014-07-081-1/+3
| | | | | | | | | | | | | Return a thread in need for help for the following scheduler operations - unblock, - change priority, and - yield. A thread in need for help is a thread that encounters a scheduler state change from scheduled to ready or a thread that cannot be scheduled in an unblock operation. Such a thread can ask threads which depend on resources owned by this thread for help.
* score: Simplify _Thread_Change_priority()Sebastian Huber2014-05-151-0/+41
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.
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