struct hrtimer_clock_base — the timer base for a specific clock
struct hrtimer_clock_base {
struct hrtimer_cpu_base * cpu_base;
int index;
clockid_t clockid;
struct timerqueue_head active;
ktime_t (* get_time) (void);
ktime_t offset;
}; per cpu clock base
clock type index for per_cpu support when moving a timer to a base on another cpu.
clock id for per_cpu support
red black tree root node for the active timers
function to retrieve the current time of the clock
offset of this clock to the monotonic base