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/posix/src/pthreadexit.c | 5 +---- cpukit/posix/src/pthreadjoin.c | 8 ++------ 2 files changed, 3 insertions(+), 10 deletions(-) (limited to 'cpukit/posix') diff --git a/cpukit/posix/src/pthreadexit.c b/cpukit/posix/src/pthreadexit.c index 40cd16023a..6b3a09af98 100644 --- a/cpukit/posix/src/pthreadexit.c +++ b/cpukit/posix/src/pthreadexit.c @@ -54,10 +54,7 @@ void _POSIX_Thread_Exit( *(void **)unblocked->Wait.return_argument = value_ptr; } while ( (unblocked = _Thread_queue_Dequeue( &api->Join_List )) ); } else { - _Thread_Set_state( - the_thread, - STATES_WAITING_FOR_JOIN_AT_EXIT | STATES_TRANSIENT - ); + _Thread_Set_state( the_thread, STATES_WAITING_FOR_JOIN_AT_EXIT ); _Thread_Enable_dispatch(); /* now waiting for thread to arrive */ _Thread_Disable_dispatch(); diff --git a/cpukit/posix/src/pthreadjoin.c b/cpukit/posix/src/pthreadjoin.c index 5033c37024..136eea6eed 100644 --- a/cpukit/posix/src/pthreadjoin.c +++ b/cpukit/posix/src/pthreadjoin.c @@ -61,13 +61,9 @@ on_EINTR: * Put ourself on the threads join list */ - if ( the_thread->current_state == - (STATES_WAITING_FOR_JOIN_AT_EXIT | STATES_TRANSIENT) ) { + if ( the_thread->current_state == STATES_WAITING_FOR_JOIN_AT_EXIT ) { return_pointer = the_thread->Wait.return_argument; - _Thread_Clear_state( - the_thread, - (STATES_WAITING_FOR_JOIN_AT_EXIT | STATES_TRANSIENT) - ); + _Thread_Clear_state( the_thread, STATES_WAITING_FOR_JOIN_AT_EXIT ); } else { executing->Wait.return_argument = &return_pointer; _Thread_queue_Enter_critical_section( &api->Join_List ); -- cgit v1.2.3