extern uint64_t time_since_genesis(void);
extern uint64_t mtime_since_genesis(void);
extern uint64_t utime_since_genesis(void);
-extern void usec_spin(unsigned int);
-extern void usec_sleep(struct thread_data *, unsigned long);
+extern uint64_t usec_spin(unsigned int);
+extern uint64_t usec_sleep(struct thread_data *, unsigned long);
extern void fill_start_time(struct timeval *);
extern void set_genesis_time(void);
extern int ramp_time_over(struct thread_data *);