get_cpu_iowait_time_us  166 include/linux/tick.h static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; }
get_cpu_iowait_time_us  607 kernel/time/tick-sched.c u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time)