[PATCH 4/4 gnumach] kern/sched_prim: Simplify by not dispatching to idle cpu directly

[Damien Zammit]

This speeds up smp to approximately full speed of uniprocessor!

---
 kern/sched_prim.c | 82 ++---------------------------------------------
 1 file changed, 2 insertions(+), 80 deletions(-)

diff --git a/kern/sched_prim.c b/kern/sched_prim.c
index 5ee0521a..cdb2ba27 100644
--- a/kern/sched_prim.c
+++ b/kern/sched_prim.c
@@ -1228,8 +1228,7 @@ void update_priority(
 /*
  *     thread_setrun:
  *
- *     Make thread runnable; dispatch directly onto an idle processor
- *     if possible.  Else put on appropriate run queue (processor
+ *     Make thread runnable; put on appropriate run queue (processor
  *     if bound, else processor set.  Caller must have lock on thread.
  *     This is always called at splsched.
  */
@@ -1262,51 +1261,6 @@ void thread_setrun(
             *  Not bound, any processor in the processor set is ok.
             */
            pset = th->processor_set;
-#if    HW_FOOTPRINT
-           /*
-            *  But first check the last processor it ran on.
-            */
-           processor = th->last_processor;
-           if (processor->state == PROCESSOR_IDLE) {
-                   processor_lock(processor);
-                   simple_lock(&pset->idle_lock);
-                   if ((processor->state == PROCESSOR_IDLE)
-#if    MACH_HOST
-                       && (processor->processor_set == pset)
-#endif /* MACH_HOST */
-                       ) {
-                           queue_remove(&pset->idle_queue, processor,
-                               processor_t, processor_queue);
-                           pset->idle_count--;
-                           processor->next_thread = th;
-                           processor->state = PROCESSOR_DISPATCHING;
-                           simple_unlock(&pset->idle_lock);
-                           processor_unlock(processor);
-                           if (processor != current_processor())
-                               cause_ast_check(processor);
-                           return;
-                   }
-                   simple_unlock(&pset->idle_lock);
-                   processor_unlock(processor);
-           }
-#endif /* HW_FOOTPRINT */
-
-           if (pset->idle_count > 0) {
-               simple_lock(&pset->idle_lock);
-               if (pset->idle_count > 0) {
-                   processor = (processor_t) queue_first(&pset->idle_queue);
-                   queue_remove(&(pset->idle_queue), processor, processor_t,
-                               processor_queue);
-                   pset->idle_count--;
-                   processor->next_thread = th;
-                   processor->state = PROCESSOR_DISPATCHING;
-                   simple_unlock(&pset->idle_lock);
-                   if (processor != current_processor())
-                       cause_ast_check(processor);
-                   return;
-               }
-               simple_unlock(&pset->idle_lock);
-           }
            rq = &(pset->runq);
            run_queue_enqueue(rq,th);
            /*
@@ -1326,28 +1280,8 @@ void thread_setrun(
        }
        else {
            /*
-            *  Bound, can only run on bound processor.  Have to lock
-            *  processor here because it may not be the current one.
+            *  Bound, queue on specific processor
             */
-           if (processor->state == PROCESSOR_IDLE) {
-               processor_lock(processor);
-               pset = processor->processor_set;
-               simple_lock(&pset->idle_lock);
-               if (processor->state == PROCESSOR_IDLE) {
-                   queue_remove(&pset->idle_queue, processor,
-                       processor_t, processor_queue);
-                   pset->idle_count--;
-                   processor->next_thread = th;
-                   processor->state = PROCESSOR_DISPATCHING;
-                   simple_unlock(&pset->idle_lock);
-                   processor_unlock(processor);
-                   if (processor != current_processor())
-                       cause_ast_check(processor);
-                   return;
-               }
-               simple_unlock(&pset->idle_lock);
-               processor_unlock(processor);
-           }
            rq = &(processor->runq);
            run_queue_enqueue(rq,th);
 
@@ -1362,18 +1296,6 @@ void thread_setrun(
            }
        }
 #else  /* NCPUS > 1 */
-       /*
-        *      XXX should replace queue with a boolean in this case.
-        */
-       if (default_pset.idle_count > 0) {
-           processor = (processor_t) queue_first(&default_pset.idle_queue);
-           queue_remove(&default_pset.idle_queue, processor,
-               processor_t, processor_queue);
-           default_pset.idle_count--;
-           processor->next_thread = th;
-           processor->state = PROCESSOR_DISPATCHING;
-           return;
-       }
        if (th->bound_processor == PROCESSOR_NULL) {
                rq = &(default_pset.runq);
        }
-- 
2.40.1