Index: libcfa/src/concurrency/kernel.cfa
===================================================================
--- libcfa/src/concurrency/kernel.cfa	(revision 6a9b12b713043629c9e3dd774ca05bc38a58822a)
+++ libcfa/src/concurrency/kernel.cfa	(revision fc59b580bf1b688acdfb86f4e29cc1f5c54fae03)
@@ -659,5 +659,5 @@
 		this.idle++;
 		/* paranoid */ verify( this.idle <= this.total );
-
+		remove(proc);
 		insert_first(this.idles, proc);
 	unlock( this );
@@ -670,6 +670,6 @@
 		this.idle--;
 		/* paranoid */ verify( this.idle >= 0 );
-
 		remove(proc);
+		insert_last(this.actives, proc);
 	unlock( this );
 	/* paranoid */ verify( ! __preemption_enabled() );
Index: libcfa/src/concurrency/kernel.hfa
===================================================================
--- libcfa/src/concurrency/kernel.hfa	(revision 6a9b12b713043629c9e3dd774ca05bc38a58822a)
+++ libcfa/src/concurrency/kernel.hfa	(revision fc59b580bf1b688acdfb86f4e29cc1f5c54fae03)
@@ -192,4 +192,7 @@
 	// List of idle processors
 	dlist(processor, processor) idles;
+
+	// List of active processors
+	dlist(processor, processor) actives;
 };
 
Index: libcfa/src/concurrency/kernel/startup.cfa
===================================================================
--- libcfa/src/concurrency/kernel/startup.cfa	(revision 6a9b12b713043629c9e3dd774ca05bc38a58822a)
+++ libcfa/src/concurrency/kernel/startup.cfa	(revision fc59b580bf1b688acdfb86f4e29cc1f5c54fae03)
@@ -492,4 +492,5 @@
 	uint_fast32_t last_size = ready_mutate_register((__processor_id_t*)&this);
 		int target = this.cltr->procs.total += 1u;
+		insert_last(this.cltr->procs.actives, this);
 
 		// Adjust the ready queue size
@@ -507,4 +508,5 @@
 	uint_fast32_t last_size = ready_mutate_lock();
 		int target = this.cltr->procs.total -= 1u;
+		remove(this);
 
 		// Adjust the ready queue size