wakeup should only call need_resched if priority is lower than current one.

[Christiano F. Haesbaert]

Heya,

wakeup_n() has a "inline expansion" of setrunnable(), but it differs by
always calling need_resched(), this sends an ipi for *every* wakeup
channel. 

It might have something to do with aja's problem.

Index: kern_synch.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_synch.c,v
retrieving revision 1.102
diff -d -u -p -r1.102 kern_synch.c
--- kern_synch.c        10 Apr 2012 11:33:58 -0000      1.102
+++ kern_synch.c        10 Jul 2012 14:27:17 -0000
@@ -378,7 +378,9 @@ wakeup_n(const volatile void *ident, int
                                p->p_stat = SRUN;
                                p->p_cpu = sched_choosecpu(p);
                                setrunqueue(p);
-                               need_resched(p->p_cpu);
+                               if (p->p_priority <
+                                   p->p_cpu->ci_schedstate.spc_curpriority)
+                                       need_resched(p->p_cpu);
                                /* END INLINE EXPANSION */
 
                        }