queue design :
	- create_central_jobq		-> trivial single list
	- create_per_accelerator_jobq	-> one core = one queue (cilk-like)
	- create_hierarchical_jobq	-> marcel-like

remarks:
	- a queue may be a set of queue (eg. for priority queues)
	- queues may have a limited size so that an extra central queue 
	  could be needed in that case ...

mecanisms :
	- steal_job_from_queue
	- push_job_onto_queue
	- equilibrate_queues	-> balances 2 queues 
	- reorder a queue

policy role :
	- implementing the push_job/fetch_job functions
	- creating the actual queues 
	- progression thread that regularly recompute a better schedule ?
		- rather do that in the context of a task submission
