linux.conf.au, January 2003
      PROGRAMMING: kernel/sched.c

 	#define BITMAP_SIZE ((((MAX_PRIO+1+7)/8)+sizeof(long)-1)/sizeof(long))
 	
 	typedef struct runqueue runqueue_t;
 	
 	struct prio_array {
 		int nr_active;
 		unsigned long bitmap[BITMAP_SIZE];
 		list_t queue[MAX_PRIO];
 	};
 	
 	/*
 	 * This is the main, per-CPU runqueue data structure.
 	 *
 	 * Locking rule: those places that want to lock multiple runqueues
 	 * (such as the load balancing or the thread migration code), lock
 	 * acquire operations must be ordered by ascending &runqueue.
 	 */
 	struct runqueue {
 		spinlock_t lock;
 		unsigned long nr_running, nr_switches, expired_timestamp,
 				nr_uninterruptible;
 		task_t *curr, *idle;
 		prio_array_t *active, *expired, arrays[2];
 		int prev_nr_running[NR_CPUS];
 	
 		task_t *migration_thread;
 		list_t migration_queue;
 	
 	} ____cacheline_aligned;
 	
 	static struct runqueue runqueues[NR_CPUS] __cacheline_aligned;