From f39f667a69cf5c4bc0dd4555537615022767f0f9 Mon Sep 17 00:00:00 2001 From: Sebastian Huber Date: Wed, 14 May 2014 13:50:48 +0200 Subject: score: Simplify _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. --- cpukit/score/src/schedulersimpleyield.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'cpukit/score/src/schedulersimpleyield.c') diff --git a/cpukit/score/src/schedulersimpleyield.c b/cpukit/score/src/schedulersimpleyield.c index ea41892ad0..65578d0bbb 100644 --- a/cpukit/score/src/schedulersimpleyield.c +++ b/cpukit/score/src/schedulersimpleyield.c @@ -26,11 +26,14 @@ void _Scheduler_simple_Yield( Thread_Control *the_thread ) { + Scheduler_simple_Context *context = + _Scheduler_simple_Get_context( scheduler ); ISR_Level level; _ISR_Disable( level ); - _Scheduler_simple_Ready_queue_requeue( scheduler, the_thread ); + _Chain_Extract_unprotected( &the_thread->Object.Node ); + _Scheduler_simple_Insert_priority_fifo( &context->Ready, the_thread ); _ISR_Flash( level ); -- cgit v1.2.3